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Catamaran Construction – Hulls, Laminates, and Composites

• Post author By BJ Porter
• Post date October 15, 2020
• 4 Comments on Catamaran Construction – Hulls, Laminates, and Composites

It’s a given that catamarans are more sensitive to weight and loading than monohulls. Catamaran builders strive to build the lightest boats they can without sacrificing strength and stiffness, and have adapted new building techniques and materials to meet this target. Cutting weight allows more passengers and gear without sacrificing performance.

And the marketing materials reflect it–they load every review and website with polysyllabic technical jargon describing the design and production choices each builder made to deliver the best boat they can.

But when you’re reading a brochure and you come across phrases like “ hand laid bidirectional GRP ” or “ vacuumed bagged e-glass with vinylester resin over a Divinycell core ” do you know what that really means?

All modern production catamarans are made with “FRP” construction (for Fiber Reinforced Polymer). Composites aren’t new–it’s just using materials together to strengthen the whole assembly. Straw was added to bricks centuries ago, and steel reinforced concrete is a staple of construction over the last century. For boats, it’s the use of stranded fibers and cured resins which make FRP different.

The term “FRP” doesn’t get into the technical detail of which fibers and which plastics, and how they’re put together to build your hull. There’s a wide variety of fiber types which can be stranded, woven, chopped or sprayed in a varied of patterns then combined with several types of resins to make hulls with different characteristics.

Some FRP techniques produce lighter, stronger shapes, while others are quicker to build and less expensive to produce. The choice of technique is a function of many factors, from the number of hulls and parts to be built, the type of parts, the budget for the project, and many design specific requirements for weight and strength.

1. FRP Basics

The principle behind all FRP construction is the same – you lay our fibers in the shape you need, then saturate them with resin, removing all the air and voids you can. Resin is left to cure, then the piece is ready to finish and use.

The reality is more complex, since building a boat isn’t like making a flat board or a simple door. You’ve got a complex shape with a designed set of curves to build. “Tooling” is the set of shapes to make the boat parts; molds to cover with fiberglass to get the right shapes.

That’s what makes FRP so effective – you can make almost anything out of it. But to do so requires a lot of choices about what you need for the project at hand.

There isn’t a “best” all around material or technique choice for all jobs, and sometimes a lower cost technique or easier to work with material may be the better solution to the problem.

A. Fiber types

Fiber choices in the last few decades have expanded past the glass fibers used in the first mass produced boats in the 1960s. FRP construction wasn’t new even then, they built the first composite boats using modern fiberglass in the 1940s.

The major fibers used in marine construction fall into three categories – glass, aramids, and carbon. The primary differences are in the strength to weight ratios of the fibers, durability, elasticity, and cost. Some construction may use blends of fiber types to combine performance characteristics.

Glass – the most common material still, because of its low cost and versatility. The most common variety used in GRP (Glass Reinforced Polymer) is “E-glass” which refers to its strand size and mineral content. Other grades have different and sometimes better mechanical properties, but may be more expensive and less appropriate for boat building use. Fiber sizes run 10 to 25 microns for E-glass, though other grades may be smaller.

Brands like Leopard, Lagoon, and most higher production volume builders use E-glass.

Aramids – this includes brand names like Kevlar, Technora and Twaron. They have higher tensile strength than E-glass, and resistant abrasion and punctures. Kevlar is a common choice for bullet proof body armor, and can built a tough, lightweight hull. The materials can be difficult to work with, as it is very tough to cut the cloth. It is often blended with carbon fiber or other materials – Catana is known for using Twaron blends in hull construction.

Carbon – the ultimate in lightweight, strong construction material. Carbon fiber is the most expensive fiber, and is available in a variety of weights, grades and strengths. Fibers are smaller than glass – down to 5 Micron.

The lightest, most expensive hulls are made from carbon, but a catamaran builder may use carbon in places other than the hull to add strength and stiffness. Carbon boards, rudders, and reinforcing structures can enhance performance without driving the price of the boat beyond reach. Carbon is the fiber of choice for many custom builds, racing cats, and Gunboat.

B. Mats, Strands, Roving, Direction, and Weights

Fibers are woven into matting and cloth for construction. Depending on the application, different weights of cloth and cloth patterns and weaves may be more appropriate for the job.

Cloth weight refers to the weight per square yard (or meter) of the cloth. A square yard of nine ounce cloth weighs nine ounces. The heavier the cloth, the stronger it is in a laminate.

Fibers carry loads along their length, so cloth weaves have directionality to their strength. Most builders use several layers of cloth with different orientations to give good universal strength to hulls. Specific FRP applications with strict load-path requirements may have more unidirectional fiber layering – for example, a chainplate manufactured from carbon fiber may use unidirectional fiber.

Cloth – fiberglass cloth is commonly used on outer layers of composites. Cloth may have unidirectional or bidirectional strength. Bidirectional cloths have maximum load strengths in two perpendicular directions. Variations on weaves like a modified twill allow a more flexible cloth for better shaping around complex molds.

Mat – is omnidirectional strands of fiber compressed into a cloth. This is often held together with a resin soluble glue, which makes mat great at conforming to mold shapes without folding and bunching as it collapses when wetted. Because the strands do not align, fiber strength is the same in all directions.

Woven Roving – a heavier cloth made from larger bundles of strands. Woven roving allows for quicker buildup of material and strand weight.

Most FRP layups include multiple layers of different cloth and mat. Finished layers may be finer cloth over courser cloth, over woven roving and mat.

Three primary resins are in common use in marine construction – polyester , vinylester , and epoxy . All resins have materials safety concerns and require care in their use and handling.

Polyester is the least expensive and requires breathing protection because of the VOC emission (Volatile Organic Compounds…nasty, smelly fumes). It doesn’t have good bonding/gluing capability, and should only be used with glass fibers for structural building. Some polyester resins are referred to as “isophthalic” resins.

Vinylester is chemically similar to a hybrid of polyester and epoxy, and performs best with fiberglass. It shouldn’t be used in high strength applications with carbon or aramid fibers. It has some adhesive qualities which polyester lacks, it shrinks less during curing, and has better impact resistance.

The added strength of vinylester coupled with increased water resistance makes it an attractive option for many catamaran builders. It costs less than epoxy, but still has better performance than polyester.

Epoxy is the most expensive, but is three times the strength of the others. It offers the best adhesion and the only resin for building structural elements with carbon and aramid. It resists water intrusion better than the other resins, resists blisters, emits no VOCs, and shrinks less. The major drawback is it is more brittle if it takes an impact.

While epoxy is “the best” in terms of strength and ease of building, there are many applications where other resins are appropriate. Budget is a big driver – a boat made from E-Glass doesn’t need epoxy resin, and considerable cost savings to meet a construction price target may drive the choice.

They can build quality boats from all material combinations, but price and performance will drive materials choices to keep some boats more affordable.

2. Cored Construction

What’s the best way to make fiberglass strong? To a point, you can make it thicker. As it gets thicker, it gets heavier. A hollow shape can take more compressive load than a solid one of the same weight, and the same principle applies to fiberglass construction.

Consider an I-Beam used in building construction. It has the same strength (or more) as a solid rectangular beam of similar mass. The compressive load on the beam is supported by the outside edges of the material, the metal in the middle doesn’t contribute much to the strength. So we can remove metal to get the “I” shape while still keeping those sides rigid, making a lighter girder with less material.

The same principle applies to cored construction with fiberglass. Making a sandwich of two layers of fiberglass with a light core between them allows for the greater strength with weight savings.

There are drawbacks – the biggest risk is damage which breaks the skin, which can let water into the core. Earlier cored construction used materials prone to saturation and rot if they got wet. Some builders opt to do cored construction above the waterline and solid below to minimize some of these risks.

But the advantages in weight savings and increased stiffness offset the drawbacks, and there may be a few other side effects like sound and temperature insulation. Like resins and fibers, core materials offer distinct advantages, disadvantages and price points.

Most builders have adopted a hybrid approach, building solid hulls below the waterline, and cored hulls and decks above. This gives a balance of weight and safety.

A. Balsa Core

Balsa is light and inexpensive. The first cored construction used balsa, but it has the disadvantage of being wood. As a natural material, if it gets wet it can rot and break down. Builders use “end grain” balsa – shorter cross cut sections – to prevent wicking of water if there is an intrusion.

B. Foam Core

Closed cell foam cores give good strength to weight savings while minimizing water intrusion. If you get water in the core, it won’t spread very far. Divinycell is a popular PVC foam core, though there are several choices with different densities and compressive strengths.

Some foam cores are not suitable for heat treatment, but infused or vacuum bagged boats like the Outremer and PDQ do well with it.

C. Honeycomb

Honeycomb cores are often the most expensive, but also give some of the best strength to weight ratios. Honeycombed cells made from resin cured aramid papers are some of the best, but also among the most costly. They offer good stiffness, but can be hard to shape. Aluminum and other resin-infused papers are other core materials builders can choose from.

3. Construction and Resin

When building a hull, there are optimal ratios of fiber to resin saturation for target strength and weight. Too little resin and you may not have enough strength (or worse, voids and gaps), and too much, and you’re just adding weight without adding strength. Resins are also a significant material cost in building the boat, so over application not only increases weight but adds cost.

There are many ways to assemble the cores, fibers and resins to build a finished laminate hull – we’re addressing the most common in boat building. Each approach has strengths and limitations, and an impact on the bottom-line cost to build the boat. Any voids or air pockets in the laminate can be disastrous; these techniques have been developed to increase saturation and reduce the risk of voids.

A. Hand Layup / Open Molding

As the name implies, this is the application of resin by hand to cloth as it’s laid into a mold. Wetting is done with a brush, and the laminate is rolled out to remove any air pockets and voids. This is the simplest way to lay up fiberglass, but also the least precise and consistent and will use the most resin.

Skilled craftsmen have built some of the finest vessels in the world this way. Though it’s more popular with monohulls, which are less sensitive to weight, many catamarans built with hand layups on open molds are still out cruising and performing well.

B. Spraying

Using chopped-strand fiber mixed with resin, a “chopper gun” can spray the mixture into a mold to lay down the composite. A consistent thickness can be difficult, but this is a low cost construction technique which makes a very resin-rich laminate. Using sprayed fibers gives lower strength in all directions compared to meticulously laid down mat and bi-directional cloth. But it is a quick technique popular with mass produced, smaller boats.

It is an excellent technique for parts with complex geometry where weight is not an issue, but you will not see it often in catamaran construction. It’s heavy with resin without any resultant increase in strength.

C. Vacuum Bagging (Wet layup)

When an open molded component has been laid up and wetted with resin, vacuum bagging takes the process a step further. After the wetting is complete, air tight plastic bagging is secured around the wetted area, and the air is pumped out of the bag. The vacuum pulls excess resin out and collapses air pockets.

The goal is to get thorough wetting and produce as strong a laminate as possible without excess resin. Knysa and Leopard are two builders that use vacuum bagging on their hulls to reduce weight.

D. Resin Infusion

For resin infusion the cloth, matting and core is laid in place dry, then sealed in an air-tight bag. A vacuum pump attaches to one side of the bag, and on the other a feed for resin. The vacuum sucks the air out of the dry cloth stack, then pulls the resin through the stack, infusing and wetting it.

Resin infusion, when done right, gives the lightest, strongest laminates with no voids and the minimum resin weight for maximum strength. SCRIMP is a variant of the resin infusion process used by some builders, including TPI which build many early Lagoon cats.

E. Pre-preg

Using pre-preg (for “Pre Impregnated”) cloth for your laminating gets rid of the resin bucket. They manufacture cloth with a partially catalyzed resin pressed into it, then it’s chilled or frozen to stop the curing process. There is no need for seperately mixed resins, and there’s no worry your resin might “go off” and harden before you’re done wetting the cloth. Instead, the cloth is assembled, vacuumed, then heated to kick off the curing process.

There are both advantages and disadvantages to using pre-preg for your laminate work. The big disadvantage is the cost; it is most expensive material to use. You also need to chill and store the cloth until you need it, though some can be at room temperature for a couple of weeks without kicking off. And you need an oven which requires some clever tricks if you’re building a forty or fifty foot boat.

But the strength to weight ratio will always be perfect. High tech honeycomb cores are best suited to pre-preg lamination, and without racing against resin cure times, you can ensure perfect cloth placement and precise layout in the build process.

The primary use for pre-preg in boating is high performance race boats. With catamarans, pre-preg may be used high load parts, like Gunboat does for foils and rudders.

4. Industry Examples

Across the catamaran building industry you’ll find almost all the above techniques and materials used, though some are less common. You aren’t likely to find chopped strand sprayed layups in ocean going cats, and hand layups can lead to heavier hulls than weight sensitive catamaran designers prefer. Most manufacturers have moved to vacuum bagging or resin infusion, with a few of the highest end boats using pre-preg for key components.

Built by Robertson & Caine in South Africa, the hull material is vacuum bagged, end-grain balsa-cored E-glass with polyester.

Hand laid, bagged vinylester over an Airex foam core in the hulls.

Earlier Prout catamarans like the Snowgoose 34 featured hand laid solid FRP hulls and decks. Over time they switched to foam or balsa cores for decks and above the waterline.

Older PDQ boats were made from vacuum bagged vinylester – solid below the waterline and cored with CoreCell foam above the waterline and in decks. Newer PDQ models switched to epoxy resin.

All glass is vacuum bagged. Below the waterline is solid E-glass and vinylester. The rest is unidirectional, bidirectional, and triaxial cloths over a Nida-Core polypropylene honeycomb core with isophthalic and vinylester resins.

The Gemini cats are built with a solid hand layup of woven roving and fiberglass mat and polyester resin. Decks are cored with end grain balsa. The Gemini 3200 introduced vinylester resin into the layup to prevent blistering.

Older Lagoons were SCRIMP infused vinylester with and end grain balsa core above the waterline and in the decks.

Newer Lagoon catamarans use polyester and vinylester resins, also infused with balsa cores above the waterline and solid below.

With a carbon fiber inner skin, Catana also uses Twaron aramid fibers in the sandwiched hull over a foam core.

Fontaine Pajot

Primary hull construction is resin-infused vinylester with a balsa cored hull and deck.

Beneath the waterline, Outremer uses a single layer, solid vinylester laminate for safety. The hulls and deck are vinylester with a Divinycell foam core. They stiffen certain components with carbon for rigidity and durability.

Gunboat hulls are epoxy infused carbon fiber with a Nomex honeycomb core. They build dagger boards and other high load components with pre-preg carbon.

• Tags Buying Advice

By BJ Porter

Owner of Hallberg Rassy 53; world explorer.

4 replies on “Catamaran Construction – Hulls, Laminates, and Composites”

Excelent. Thank you for this I learned allot. Johan

Very straight forward information. Thankyou for doing this.

Damn…What an Amazingly Informative Article. *Cheers*

Outremer publish on their website that they use polyester. Not vinyl ester as you have stated.

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Catamarans and Trimarans

Catamaran and Trimaran Boat Plans make it a reality to build your own catamaran or trimaran. Multi-hulled sailing vessels are a special class of boat. A very different mind set is required when thinking about sailing a multi hull, let alone getting your head around building one.

There are some unique challenges building a multi-hull sail boat, the extra beam added by each hull for instance can create storage issues while under construction. Hartley boat plans make the build process straight forward for even amateur builders. However with all things considered, building a multi can be an amazing journey.

Fast Twin Catermaran

Lively 28 Cruising Trimaran

Lively 35 Cruising Trimaran

How To Create the Perfect Cruising Catamaran Layout

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More than ever before, sailing fans are gaining an interest in catamaran layouts and designs that define performance. Many others are also looking into either buying a cruising catamaran or designing and building one. While building a catamaran is no piece of cake, this article shows you how to create the perfect cruising catamaran layout. 

To create the perfect catamaran layout, carefully consider factors like a good hull design, optimal helm station placement, boat stability, and adequate load-carrying capacity. Excellent galley positioning, ease of handling, and spacious living and sleeping quarters are also crucial. 

The modern cruising catamaran is a far cry from the simple Polynesian double canoe of old. That’s because structural innovations and new composite materials have resulted in multihulls with impressive cruising abilities. Keep reading to learn more about exceptional catamaran layouts.  

The Changing Trends in Catamaran Designs

The early cruising catamaran designs resulted in boats that could sail much faster than traditional sailing boats. In addition, they could glide with ease in shallow waters and required less wind and crew. Unfortunately, these cruising cats were heavy, had small, cramped interiors, and boasted somewhat challenging handling abilities. 

Today’s cruising catamarans are different. They boast the utmost comfort, high speeds, and the safety of a well-designed cruising yacht. They are also more exciting, visually appealing, deliver the smoothest of rides, and sport more spacious interiors. 

Have a look at the below video showcasing the top ten cruising catamarans:

Features To Look Out for in Catamaran Design Layouts

Cruising catamaran designers understand what most sailors look for in a cruising vessel. They, therefore, design cruising multihulls that address these pertinent issues and more. Some of the features you might want to consider having in your dream boat include the following:

• Responsive performance. Outstanding performance allows for pleasurable cruising and ensures your safety since you have more options during difficult weather.
• Excellent load-carrying ability . This allows you to have an extended cruising vacation or ocean crossing.
• Boat stability . Go for lightweight, robust construction, which results in a lot of buoyancy.
• A low center of gravity for smooth rides and enhanced performance. Centering weight around a low center of gravity improves the overall sailing quality, reduces pitching movement and reduces the risk of capsizing .
• Adequate bridgedeck clearance to reduce slamming and provide better performance in rough conditions. A high bridgedeck also means less noise and slapping action from the waves hitting the boat bottom, thus ensuring a quieter, smoother ride.
• Comfortable sailing. To enjoy a quality life on board, you need comfort while at sea. Thus, elements like gentle movement, no creaks or groans, no bridgedeck slamming, and minimal pitching are essential for quality, peaceful and restful sleep.  

Now that you know what a cutting-edge catamaran features, let’s look at how to create the perfect cruising catamaran layout.  

Build a Larger-Sized Catamaran

The early catamarans ranged between 36-42 feet (10.9-12.8m). At the time, this appeared to be a good size in terms of safety and ease of handling. However, the boats were heavy, and the additional drag and displacement adversely affected their performance and windward ability. 

It’s now possible to make the new generation catamarans lighter, larger, and more spacious with excellent power-to-weight features. The current trend is larger-sized catamarans in the 45-50 feet (13.7- 15.2) range. Composite engineering and technologically advanced equipment such as furling systems, electric winches, and autopilot make it easier for a smaller crew to sail larger boats with confidence. And to do so without compromising safety or stability. 

Get the Best Catamaran Hull Design

A cruising catamaran’s performance depends on three main aspects; its length, the sail area, and the boat’s weight. Long boats are generally fast. A light boat with more sail area is also faster than a heavier boat with less sail area. In other words, you can make a multihull faster by making it longer, lighter, or adding more sail.

However, there are exceptions to this rule; a boat with too much sail area is more likely to capsize if there are brisk winds. Also, if the boat’s design makes it too light, it’ll be unable to handle much punishment, while a hull design that’s too slim would make the vessel incapable of carrying any significant loads. But that’s not all; if the boat is too long or too large, it’ll become grossly exorbitant. Narrow hull shape might also mean smaller cabins.

Nonetheless, these three factors alone are not enough to determine a cruising catamaran’s performance. While faster boats boast finer hulls, the wetted surface area tends to increase as fineness increases; thus, fine hulls end up becoming less fast in low wind speeds. Also, very wide hulls mean a reduction in actual performance.

The Prismatic Coefficient (Cp), a measure of how full the ends of the hull get, is the most essential design hull shape factor for any catamaran. A high Cp equals high speeds, although you can still use a lower Cp if you have fine hulls. Nevertheless, the key to a good Catamaran design is a higher Cp for fast sailing. 

To achieve a high Cp, there are several things you can do: 

• Fit bulb bows . Unfortunately, the bulb bows tend to slam in a seaway when you do this.
• Have an extensive planning aft section . However, this can increase the wetted surface area, WSA and lead to additional challenges. 
• Flatten out the hull rocker and add a bustle aft. This helps to add displacement aft. 

Build Convertible Main Living Spaces

The open cockpit is now a thing of the past. Instead, pioneering designers for catamaran manufacturers like Nautitech, Gunboat, and Catana now replace traditional-style salons, cockpits, and cabins with spacious indoor and outdoor living spaces. The concept involves merging separate saloon and cockpit areas with duplicate lounge spaces and the use of hard-wearing composite materials. 

You can also design the cabin to suit your preferences. You may decide to add a cabin or remove one, add a bathroom, have the forward berth in the hull or on the wing deck.

• The design enhancements boost usable space while opening up the living areas.
• It reduces time and costs for interior maintenance and cleaning. 
• Large windows bring in more light, increasing visibility. 
• Luxurious, spacious, and airy owners’ cabins provide more comfortable living space. 

Bulkhead Helm Stations vs. Twin Stern Steering

Many catamaran owners have traditionally preferred bulkhead steering. This helm position remains popular, but twin stern steering positions come with more advantages since they provide greater sails visibility. The twin stern positions are also best suited for racing or day sailing since they often lack adequate protection for extended cruising. 

Exposed helms are not ideal for a long ocean passage. Go for a safe, secure, and well-protected helm station that provides good visibility and comfortable space for long watches. Again, it’s best to have all control lines at the helm to establish a static control station. Also, have all push-button-controlled winches, instruments, windlass, and autopilot prominently located inside the cockpit. 

• Twin stern steering positions give you a better view of the sails
• You get a better feel for overall sailing conditions.
• Twin stern steering positions lack the necessary protection for extended cruising. 

Go for the Flybridge Design

The flybridge design is appealing because it offers excellent visibility, more comfort, and additional entertainment and lounging space for everyone on board. Unfortunately for smaller boats – those below 50 feet (15.24m), there is minimal protection from the elements. As such, you might want to consider adding enclosures to offer protection. The flybridge, thus the helm, remains cut off from the vessel, which makes communicating with the crew a challenge. 

• It provides great visibility.
• It offers comfortable spacing. 
• It might be unsafe to move from the cockpit to the flybridge in bad weather.
• It isn’t easy to communicate with the crew.

Daggerboards vs. Fixed Keels

Average cruising catamarans typically utilize fixed keels while high-performance cats have daggerboards . Fixed keels allow you to beach your catamaran easily, and your hull remains intact if a collision occurs. While you lose some angle when sailing upwind, you gain more interior space in the hulls that you can put to good use.

Daggerboards are essential in a performance cruising catamaran since they guarantee that the boat delivers good upwind sailing, including during difficult situations. During long passages, they allow you to point better upwind though the drawback is that they consume much interior space within the cruising catamaran’s hulls.

Since flying on foils ( hydrofoils ) isn’t that practical on cruising catamarans, designers of larger-sized boats have also come up with modified daggerboards. These daggerboards produce lift and prevent leeway, too, thereby improving performance significantly, as seen with the Catana 59’s curved daggerboards. These foil-like daggerboards lift the boat ever so slightly upon reaching higher speeds, making it feel less heavy and much faster. 

At the end of the day, calculating the performance of a boat sailing in a wide range of varying seas and winds might not be easy – despite a daggerboard or fixed keel configuration. This is because upwind speed depends not only on the sails’ quality but also windage and the height of the bridgedeck beyond the water.

• The design innovations -curved daggerboards and hydrofoils- improve catamaran performance significantly.
• Daggerboards enable you to access otherwise inaccessible anchorages.
• Daggerboards take up hull space in the hulls of your vessel.

Galley Up vs. Galley Down

Galley layout are becoming more and more important as more people, including families, start sailing regularly. While at sea, your galley needs to be a safe place, well-ventilated, and functional. Everything should be well-thought-out for the sailor’s comfort, including handholds to make it safer to move around the boat. 

While the galley location can either be up the bridgedeck or down in the hull, galley up appears to be the most popular trend. This makes the galley the focal point of both the living space and entertainment areas.

If you have a family, this placement is ideal since you make your meals from the galley and get to spend most of your time here. Many cruising families and couples prefer this arrangement and find separating the galley down the hull unappealing. Besides, carrying hot food up and down the staircase is unsafe.

Still, galley down is ideal for charter boats since it offers a private cooking area and uses up hull space efficiently.  

• Having the galley on the bridgedeck is ideal for families and cruising couples.
• Placing the galley on a similar level with the serving area and cockpit is safer and less tiring.
• There’s better ventilation on the bridgedeck, making for comfortable cooking. 
• There’s less kitchen privacy galley up.
• On smaller catamarans, this layout can impact the size of the saloon seating area significantly.

Production Catamaran vs. Custom

The choice of either a production catamaran or a custom design might seem pretty straightforward. Production catamarans from major brands come backed by proven designs, dependable construction, solid warranties, and many years of experience. The catamarans are easy to service, source for parts, and most – particularly the owner’s versions – hold on to their value, making them much easier to resell. 

On their part, custom boats are fantastic in that you can tailor them to your exact needs. However, they might be more challenging to maintain or service. That’s because of parts unavailability and lack of construction knowledge.

Choose Quality Construction Materials

The best quality materials to use on your catamaran are both light and robust. While carbon fiber is great, plywood, plywood/epoxy, and strip-cedar are excellent materials too. What’s more, they are also affordable, so you don’t have to get too hung up on cutting-edge building materials. What matters is build quality; thus, a well-built plywood catamaran boat can last as long as a boat made from more high-tech materials. 

Combining various materials also helps combat some of the issues that plague plywood boats in terms of resale value. At times, the design tends to make the boats appear pretty dated.  

• Plywood and strip-cedar materials are affordable and provide excellent build quality. 
• Plywood boats may have a lower resale value than those built with modern materials.

Consider Ease of Handling

An important factor in handling a cruising catamaran is deck layout. Most cruising catamarans sailed short-handed , so if your boat has one helm, all lines should run back here to allow for a static control station for the entire boat. 

The other essential element is visibility from the helm. The 360 degrees of visibility while maneuvering, docking, or underway is crucial to your boat’s safety, as well as life and property. As such, you should be able to view both bows, or at least the pulpits and sterns, while standing at the helm. If not, you may have challenges handling the boat due to blind spots.

Consider the Load Carrying Capacity

A well-designed catamaran is enjoyable to sail in all weather conditions. It’s also much easier to handle than a monohull because of its widely spaced twin engines. But when you immerse extra hull depth, the vessel gets sluggish and moves slower, maneuvering in tight spots or when docking becomes more challenging. Furthermore, the hull submersion reduces bridge deck clearance, leading to hull slamming. 

To allow for adequate load carrying capacity, you need a design that provides a generous displacement. This helps to ensure that you maintain reasonable bridge deck clearance even when fully loaded. It also allows you to avoid digging big holes in the water as you drag your transoms. 

Displacement refers to the amount of buoyancy designed into the hulls, which essentially means that your boat will cruise better if its weight is less than your designed displacement.

Note that an overloaded catamaran not only loses out on performance but eventually, on safety too. To counter this, choose a lightweight catamaran with hulls bearing cored construction and interiors made of lightweight materials.  

Remember, when you go cruising, you will need to carry fuel, extra water, supplies, equipment, and amenities, translating into thousands of extra pounds. Therefore, try and avoid the following design errors to ensure that your catamaran has an adequate load-carrying capacity:

• Avoid putting in place too much accommodation space.
• Avoid building a heavy boat ‐ use low-tech construction materials.
• Avoid installing inboards in a small boat.
• Lightly constructed catamarans perform faster and carry more weight.
• Cored construction makes for a strong and stiff catamaran, thus enabling good performance.

Final Thoughts

A well-designed cruising catamaran is a joy to behold. Today’s modern technological advancements mean that you can buy or build a light but strong cruising catamaran. And as you can see from this article, there are many excellent cruising catamaran layouts that you can choose from. 

However, whichever layout you decide on needs to fit your sailing needs and purposes to ensure you remain comfortable and safe while at sea. Above all, ensure that you go for a vessel that you can handle with ease in all weather conditions.

Owner of CatamaranFreedom.com. A minimalist that has lived in a caravan in Sweden, 35ft Monohull in the Bahamas, and right now in his self-built Van. He just started the next adventure, to circumnavigate the world on a Catamaran!

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Category: Our Catamaran Build Kits

Recommended equipment.

Quality suppliers & manufacturers

The schionning team have a lot of contact with equipment suppliers and manufacturers, and hear feedback on certain brands or systems from our many customers. there are many schionnings cruising the world and testing products longevity and the customer service offered by the manufacturer., on this page we will list products and companies that we know to provide above average quality and service. it is always growing, and if your company provides equipment used on our designs and you would like to be included - please contact us., engines & drive systems.

Visit:  https://oceanvolt.com

Batteries, Power Management

LITHIUM POWER (VIC)

Back in 2013 I knew that my boat batteries were reaching the end of their lives, I had been researching LiFePO4 cells for a few years and decided that I should install them. Unfortunatly I was unable to find a local supplier. So Lithium Power was established.

Technical Information

The technical information page is a collection of documents (mostly in pdf format) on the materials and systems used in schionning catamarans. including data sheets, engineering information, strength comparisons of each core material and informative articles from jeff outling the design of certain system such as engine choices and main sheet systems., detailed engineering data for your research, we understand that getting your head around the process of building your own boat, or having one built, can take a little while. to gain a greater understanding of the materials used in our designs, the below data sheets have been supplied by atl composites, and contain all of the technical data you could need regarding the composites we use. in addition are articles or documents written by jeff about certain systems used on our designs and why., all technical information and data sheets on west system/duflex/durakore provided courtesy of atl composites. for more information please see the atl composites website here., documents library.

Information Sheet – CE CERTIFICATION PROCESS

• Mainsheet Systems for Catamarans
• Motor Choices for Schionning Designs
• Weight and Weight Distribution Schionning Designs
• Schionning Designs Sailing Performance and Tips
• Hull Shapes and Performance – Power Designs
• Outboard Engines VS Diesels – Written by Ross McCombe
• An Outboard Installation That Works – Ross McCombe Follow up
• Data Sheet – DUFLEX BALSA for Catamaran Kit Builds
• Data Sheet – DUFLEX FOAM
• Data Sheet – FEATHERLIGHT Paper Honeycomb
• Data Sheet – WEST SYSTEM R105
• Data Sheet – PUMP SYSTEMS
• Data Sheet – MICROFIBRE BLEND 403
• Data Sheet – MICROLIGHT 410
• Data Sheet – MICROSPHERES 411
• Information Sheet – USING FILLERS
• Data Sheet – KINETIX RESIN Thixotropic
• Information Sheet – DURAKORE PLANKS 413
• Data Sheet – DURAKORE PLANKING 414

Kit Materials Contents

Kit materials' contents, so if you order a schionning kit, what exactly is going to arrive see an overview of the materials you will receive, and what each is used for during the build process. fibreglass cloth or tapes microspheres, microballoons or microfibers take a closer look and you can answer these questions., our schionning kits are a no nonsense, common-sense approach to building a boat. we offer great service, fast delivery and access to anything you could need for your boat straight from the supplier to your door. our construction plans and kits are sold with 100% professional boatbuilder support via phone and email, any time you're unsure or just need a second opinion, we're here..

Our kits contain all of your basic materials to build your boat to a faired shell stage, ready for painting and fit-out. We have sail-away costing estimates available for all of our standard designs, and this will give you an accurate idea of the overall cost of your project. This costing varies depending on your level of finish, as you can imagine different options vary greatly in price.

Below is a quick glance at what your Schionning Kit will include and what each item is primarily used for, we hope this is helpful and if you should require more detailed information please don’t hesitate to contact our office.

What do I actually receive?

DUFLEX PRE-LAMINATED PANELS

DuFlex pre-laminated panels are the main and most important material used in our kits, predominantly in the flat panel designs, however they are used in Strip-planked designs also, though to a lesser extent. These panels are 2400mm x 1200mm and are CNC routed to speed up build time on our Wildernes X Series, as well as some of our power designs. For internal furniture, a paper honeycomb core is used instead of the end-grain balsa wood core that is used for main structural areas. The use of this is purely to save weight in the shell and therefore produce a faster, more responsive catamaran.

KINETIX LAMINATING RESIN & HARDENER

WEST SYSTEM EPOXY RESINS

FIBREGLASS TAPES (DOUBLE BIAS)

CARBON FIBRE CLOTH

FIBREGLASS CLOTH

The kit process, building your own boat can be a daunting prospect, however to demonstrate each step in the kit assembly process, we've created this guide for you to study. as you can see our kits are the ultimate in building efficiency and have been streamlined over 30+ years to ensure that you're on the water faster and with less effort., how does it all go together.

The first step to building your dream catamaran begins with a strongback – this is a square frame used to position the temporary frames that will be used to form the hull shape. This frame will be set up and must be square and accurate, a string or laser level can be used to achieve this.

The forebeam is now installed along with the striker attachment fitting, as shown above. The bridgedeck is installed shortly after and taped onto the bulkheads with webs installed, this now completes what is a quite stiff and strong platform to work on.

Now that the bridgedeck is in place, the forward webs and dash will be fitted. At this stage, all furniture and internal work begins, with the main panels left off for ease of access when working.

Material Choices

Schionning material choices, solutions that work best for catamarans & why, our designs are based on cored composite construction techniques using west system epoxy resin and knitted fabrics. but given the range of today's composite technologies, which solution works best for catamarans and why written by jeff schionning, selecting the correct materials, resin choices.

It also fully protects the boat against water absorption and it can not develop the dreaded Osmosis.

We choose ATL Composite’s resin systems for their superior quality, reliability and value for money.

Having worked closely with the ATL Composites team and their products for many years, we know we can stand by their material solutions, and rely on great service should something unexpected happen.

This may not seem important but when working with a material for an extended period of time, the small things make all the difference.

CORES Which One to Use?

• End-Grain Balsa – 150kg per cubic metre
• Superlight Balsa – 94kg per cubic metre
• Western Red Cedar – 360-380kg per cubic metre
• Foam – 80kg per cubic metre

BALSA END GRAIN (150 kg/cubic metre)

Balsa  has very good values and we can produce a shell using a very light laminate. It will be very stiff and very resilient to fatigue.

It has exceptional qualities including very high compression strength, extremely good sheer capabilities and fantastic sheer stiffness.

Compressive strength is the resistance to collapsing when pressure is applied perpendicular to the surface as when pushing directly onto the material with the point of your finger. Balsa is far stronger than Foam (80kg/cubic metre) in compression.

Balsa is also very strong in shear. This is when the core sample is held flat between your hands, one hand slid one way and the other slid the opposite way, when the core tears through the middle the core has failed in sheer. The amount of stretch you feel before the core shears is shear stiffness. To compensate for sheer weakness the core is made thicker. So 13mm Balsa may be equal in sheer to 19mm Foam.

(80 to 200 kg/m³)

There are many boats sailing that are built from foam as it’s mechanical properties are good for boat building.

• Initially one would expect this cat shell to be lighter as it is ½ the weight of Balsa. We do have to compensate for its weaknesses and will then add to the reinforcement the reinforcement on the outside to spread that compression load over more core and need a triaxial type weave to compensate for the veneer content that runs fore and aft on the Durakore.
• Secondly, we need to increase the Core thickness to compensate for the shear value, usually neutralizing the weight advantage.
• We only use structural foam core that is closed-cell and cross-linked.

The end result using foam core amounts to a very similar total boat weight. Professional builders can achieve a good result but usually use vacuum bagging and very good molds to achieve this.

Secondary Issues

Balsa can absorb water. It needs extreme neglect to rot (very unusual). Water soaks along the end grain quickly. It travels very slowly across the grain. We use balsa under the waterline especially because of it’s high compression strength for beaching etc. any core type must be sealed. Damage to all cores results in the same sort of repair. Notice a damp spot remaining when drying out to anti-foul… simply grind back the surface glass exposing the core, dry it out and re-glass – it’s that easy.

Timber cores are cheaper than Foam in most cases.

A light, high tech cat returns a far better (often 2 – 3 times) re-sale than lower tech materials. Often saving $10,000 on materials initially, loses $200,000 on re-sale – a serious reality.

Our boats can be built using Balsa, Foam or Western Red Cedar. Combine strength, stiffness, lightness and cost, with ease of use – it just makes good sense!

BUILD YOUR RAKU CAT WITH A DuFLEX KIT BY FOLLOWING THESE NINE BASIC STEPS

Step 1. Kit Design

Work with us to finalise the details of the design you have chosen including any design options or additional modules to be included in the kit.

We will determine the laminates, the number of panels required for each laminate, create the cutting files and prepare a quote for the kit if it is not already priced.

Once the design details and pricing are confirmed you are ready to place your order.

Step 2. Unpacking

2. The kit arrives at your workshop door, usually by container, as a stack of 1.2m x 2.4m routed composite panels ready to be joined. The shipment will normally include additional reinforcements, resins, and ancilary products as specified.

Unpack the shipment and stack the panels out of the way of the space where the panels will be joined.

If you have purchased a joined kit many of the panels will already be joined up to the length that can be shipped in a container (12m).

Step 3 Joining the Panels

Set up the work space where the panels are to be joined.

The panels have a scarf join called a Z join that facilitate the join without needing tapes.

The joining can be done with a heated Z press that cures the epoxy join quickly. Alternatively they can be joined with clamping pressure.

If the panel are are being joined with the Z press you will need an elevated work bench the full length of the longest panels you are using. (image below).

If you are joining them with a clamping technique the space can be on the factory floor.

A nesting booklet is provided with the kit to show how the panels are joined (right)

Joining the panels with  clamping pressure

Panels are being joined into a single long panel by painting the surfaces of the scarf join with epoxy screwing through plywood battens that have a release film applied to one side.

Joining the panels with the Z Press

Step 4 Stacking Joined Panels

Once the joins are cured the panels are stacked to one side until they are needed for the job. The inividual parts should not be cut free of the panels until they are required.

Bulkhead and floor panels will be needed before the hull sides and cabin top so they should be left to the front of the stack wherever possible.

Step 5. Separating the Parts

When assembly is ready to begin the individual parts are separated from the panels by cutting the joining tabs. It is likely you will be building onto moulded hull bottoms that have been built from strip planking or another method of building moulded components. The process for building moulded components is described in another article.

Step 6. ASSEMBLY

As the joined panels are assembled onto the job you will need to apply glass tapes to the joins as specified in your plans.

Panels can be surfaced and coated inside and out with high build while they are on the workshop floor to minimise fairing time once they are assembled to the boat. The paint on the panels shown here has been kept back from the edges to provide a good bond for the tapes.

Smaller items such as steps, seats and dagger cases are nested into the kit and for the more complex parts diagrams are provided to assist with the assembly process.

Step 7. Interior

Interior kits can be ordered with the primary kit, or they can be ordered later when final decisions have been made about the interior arrangement.

A compromise solution is to order the interior as a set of plain planels that can be cut to shape on site after finalising the layout.

Step 8 Fairing, Painting, Hardware Installation

8. The DuFLEX construction process goes a long way to minising the amount of fairing that has to be done, but inevitably any boat that has not come out of a female mould will require some level of fairing and surface preparation prior to painting. 

The fillers and resin systems required for the fairing work are normally supplied as part of the kit.

Hardware installation is the same as for any other form of construction using high density core inserts or consolidated laminate in way of fittings.

Step 9. Sailing

Go Sailing. This Barefoot 40 Catamaran was built entirely with a Duflex kit in Foam/Glass and Epoxy resin systems from ATL Composites

DuFLEX Kits are manufactured and supplied world wide by ATL Composites

atlcomposites.com.au

And in Europe by VDL Composites

www.vonderlinden.de/her/28/vdL-Composites-GmbH

For more information on DuFLEX and associated Products 

atlcomposites.com.au/category/27/DuFLEX

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How to Build a Catamaran Boat? (Step-by-Step Guide)

Building a catamaran boat from scratch is a rewarding and challenging endeavor.

It takes a combination of skill, dedication, and hard work to craft a seaworthy vessel.

In this step-by-step guide, you’ll learn how to design and size your catamaran, gather the necessary materials, cut and assemble the pieces, lay fiberglass and apply epoxy, make finishing touches, add hardware and paint, and rig the boat.

With the right tools, planning, and patience, you can make your dream of sailing in a catamaran a reality.

Table of Contents

Short Answer

Building a catamaran boat requires a lot of patience and skill.

The first step is to choose the right materials for the hull, such as fiberglass, wood or aluminum.

Then, you will need to build the frame of the boat, which includes the crossbeams and the main hull.

After that, you will need to install the decking, the rigging, and other components.

Finally, you will need to paint and varnish the boat, as well as install the outboard motor and other accessories.

Design & Size Considerations

When it comes to building a catamaran boat from scratch, the first step is to determine the design and size of the boat.

This should take into account the intended use of the boat, such as sailing, fishing, or leisurely cruising.

The size of the boat will depend on the number of passengers and the type of activities the boat will be used for.

For instance, a larger boat may be needed if passengers will be standing or participating in watersports.

The design of the boat is also important and should be chosen based on the intended use.

If you are looking to build a sailboat, you will need a design that is optimized for sailing.

On the other hand, if you are looking to build a fishing boat, you will need a design that is optimized for fishing.

There are a wide variety of boat designs available, so it is important to research and choose the one that best suits your needs.

In addition to the design and size, you will also need to consider the materials used for construction.

The most common materials for building a catamaran boat are wood, fiberglass, and epoxy.

Each material has its own advantages and disadvantages, so it is important to research them and determine which one is best for your project.

Finally, you will need to consider the cost of the project.

Building a catamaran boat from scratch can be a costly endeavor, so it is important to have a budget in mind before you begin.

The cost will depend on the type of materials used and the complexity of the design.

It is also important to factor in the cost of any tools that may be needed for the project.

By taking into account the design and size, materials, and cost of the project, you can be sure to build a catamaran boat that meets your needs and budget.

With the right amount of patience and attention to detail, you can build your own catamaran boat in no time.

Gathering Materials

Gathering the materials needed to build a catamaran boat from scratch can be a daunting task, but it is essential for creating a sturdy and safe vessel.

Before starting the building process, it is important to have an accurate and detailed plan for the boats design and size.

Once a plan is in place, it is time to begin sourcing the necessary materials.

The most common materials used to construct a catamaran boat are wood, fiberglass, and epoxy.

When choosing wood, it is best to select a species of timber that is strong and durable, such as mahogany, teak, or cedar.

Additionally, the wood should be clear and free of knots, splits, and other defects.

Fiberglass is a lightweight fabric that is resistant to water and provides additional strength to the boats hull.

Epoxy is a waterproof adhesive that is used to seal the boat and ensure that it is watertight.

It is important to ensure that the materials are of high quality, as this will help to ensure the boats longevity.

Additionally, it is important to purchase the necessary materials in the correct amount and size.

Too little or too much of a material can be a costly and time-consuming mistake.

Finally, it is important to keep any leftover materials for future repairs or modifications.

With the right materials gathered, the next step is to cut the wood and begin the assembly process.

Cutting & Assembly

Cutting and assembly are the most important steps when it comes to building a catamaran boat from scratch.

The first step is to decide the design and size of the boat.

This will determine the type of materials you need to gather and the amount of effort that needs to be put into the project.

After deciding on the design and size, you will need to cut the wood to fit the design.

This includes cutting the wood to the desired size, as well as cutting any additional pieces that may be needed to complete the design.

It is important to ensure that all the pieces fit together correctly and securely, as any mistakes could lead to a weak boat.

Once the wood has been cut, it is time to assemble the pieces together.

This involves attaching the pieces together with glue, screws, and nails, and ensuring that the pieces fit together securely.

It is important to be careful and patient when assembling the pieces, as any mistakes could result in a weak and unstable boat.

Once the frame is ready, it is time to lay the fiberglass, and apply the epoxy to seal the boat.

This is an important step, as it will make sure that the boat is waterproof and durable.

Finally, you can add the finishing touches, such as the hardware, paint, and rigging.

With the right amount of patience and attention to detail, you can have your own custom catamaran boat in no time.

Laying Fiberglass & Applying Epoxy

When laying the fiberglass and applying epoxy, it is important to take your time and be precise.

Fiberglass and epoxy are key components of a catamaran boat, as they provide the strength and waterproofing necessary to keep the boat afloat.

Start by laying the fiberglass over the frame of the boat.

Make sure to cut the fiberglass to size and overlap the edges for a strong seal.

Once the fiberglass is in place, mix the epoxy and begin to apply it.

It is important to apply the epoxy in a thin, even layer to ensure a proper seal.

Make sure to move the epoxy around to get it into all the nooks and crannies of the boat.

Allow the epoxy to cure and then you can begin to add the finishing touches.

Finishing Touches

Once the frame of the catamaran boat is built, it is time to add the finishing touches.

This includes adding the necessary hardware, painting, and rigging the boat.

Hardware: Before adding the hardware, it is important to ensure that the frame is stable and secure.

Add the appropriate hinges, screws, and nails to the frame.

Make sure that the screws and nails are the correct size and do not exceed the recommended load capacity of the frame.

Painting: Once the hardware is added, it is time to paint the boat.

Choose a paint that is suitable for the materials used in the construction.

Make sure that the paint is applied evenly and that the frame is completely dry before applying the next coat.

Rigging: The last step is to rig the boat.

This involves attaching the sails, running rigging, and standing rigging to the masts and booms.

Make sure that the rigging is properly tensioned and secured.

Once all of these steps are complete, your catamaran boat is ready to sail.

Hardware & Paint

The last step in building a catamaran boat is to add the hardware and paint.

This step is often the most rewarding, as it is the finishing touch.

Depending on the design of your boat, there are various types of hardware you may need.

Some of the most common items are cleats, winches, fasteners, and decking.

After selecting the required hardware, you will need to install them on the boat.

It is important to use the correct type of screws and bolts, and to secure them tightly.

Once the hardware is installed, it is time to apply the paint.

The type of paint and color you choose will depend on the design of your boat.

It is important to use a high-quality marine grade paint that is designed to handle the extreme environment of the ocean.

If you are up to the challenge, you can add some custom artwork or detail to your catamaran boat.

Adding the hardware and paint is the final step in building a catamaran boat.

With patience and attention to detail, you can create a beautiful and unique boat that will last for many years.

Be sure to take your time and enjoy the process of constructing your own boat.

Once you have finished the frame, fiberglass, and epoxy of your catamaran boat, you will need to move onto the rigging.

This is a crucial step in the construction process, as it will keep your boat safe and secure on the water.

When rigging a catamaran, there are a few key components that must be taken into account.

First, you will need to determine the type of rigging you will be using.

Typically, catamarans use a combination of standing and running rigging.

Standing rigging consists of cables and lines that stay in a fixed position to provide stability and strength to the boat, while running rigging consists of lines that are used to adjust the sail and mainsheet.

Additionally, you will need to choose the right type of rope and hardware for your rigging setup.

The rope should be strong and durable, and the hardware should be made of stainless steel and be corrosion-resistant.

Once you have chosen the type of rigging and hardware, you can start assembling the rigging lines.

This process involves carefully measuring and cutting the lines to the proper lengths, and then attaching them to the mast and boom.

Depending on the type of rigging setup, you may also need to attach the lines to the hulls and deck.

It is important to inspect the rigging lines and hardware regularly to ensure that everything is secure and in proper working order.

Rigging a catamaran boat can seem like a daunting task, but it is essential for the safety and comfort of your vessel.

With the right tools, materials, and attention to detail, you can successfully and safely rig your catamaran boat.

Final Thoughts

Building a catamaran boat is a rewarding experience that requires patience and attention to detail.

With the right plan, materials, and steps, you can build your own boat in no time.

Now that you know the basics of how to build a catamaran boat, why not grab your tools and get started on your very own project? With the right motivation and dedication, you can make your dream of owning a catamaran boat a reality.

James Frami

At the age of 15, he and four other friends from his neighborhood constructed their first boat. He has been sailing for almost 30 years and has a wealth of knowledge that he wants to share with others.

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Open Source 13-15m Catamaran Plans

Discussion in ' Projects & Proposals ' started by archie1492 , Jan 3, 2018 .

archie1492 Junior Member

Dear all, I want to create a detailed building information model for a 13 - 15 meter catamaran that is capable of being CNC cut and assembled. I need some help finding plans I can use as a basis of design. Specifically, I need the hull profile information. Section cuts through the hull will give me the ideal contours for a boat of this size. Can someone help? After weeks of searching, I still cannot find these online. For now, this is merely an exercise in my 3d modeling capability. I'd like to share my drawing work with the forum if I can get some assistance to start off. There are future possibilities I am also considering. I'm an experienced Architect & construction designer with a strong background in computer aided design. Once I've modeled the boat in 3d, I would like to flatten the various parts and create plans for the individual boat parts to be CNC cut. I would like to build a small scale model first (1:2o or perhaps 1:10) with the ultimate goal of building the boat full scale.  

TANSL Senior Member

This is a very simple catamaran which, if you are interested, I can give you a lot of information. It is not a spectacular boat but it can help you in your first steps with boats. LOA = 16 m, Lbp = 14.6 m  

Thanks I really appreciate it. The hull lines for the motor cat you've provided are not quite what i'm looking for. I'm specifically looking for the hull lines for a 14m catamaran sail boat. I guess there is some standard for these contours especially the area below the waterline. Check the attached document as well if anyone is interested in this.  

Attached Files:

catdimension.pdf

I'm sorry, you never specified that it was a sailing catamaran. I thought that to carry out your purposes, " For now, this is merely an exercise in my 3d modeling capability ", any model was valid. Apparently, you have different purposes than, in addition to, to practice with 3D models. The better you clarify what you are really looking for, the better someone can help you.  

Hi all, Here's an example of what kind of information I need to get started. Optimising Hull Lines for Performance https://www.graingerdesigns.net/the-lab/optimising-hull-lines-for-performance/ The boat shown here is a 8.5m cat sailboat. I'm looking for something a bit larger in the 14m range. Also, the images only show one of the hull profiles. I'd like profile lines for the entire boat. I will post some other images I've found online showing profile lines for smaller boats. I still cannot find any 14m hull lines. Can anyone help?  

grainger_1488019480.jpg

Grainger_1488019410.jpg, grainger_1488019333.jpg, grainger_1488019265.jpg, grainger_1488019219.jpg.

Here are some other hull lines I've found online. Hope this is useful to anyone else looking for this information. Thanks!  

Evergreen Lines small.jpg

Hull-lines.jpg, shark-20.jpg.

You could take any of those boats and scaleb the lines to get the desired length. Since it is only a 3D modeling exercise, you do not have to worry about anything else. You could even make a mix of 2 or 3 of those models to get the one you are looking for.  

Thanks Tansl, I'd like to make the boat drawings accurate for the 14m size. Perhaps one day I will develop this into something worth building full scale. The more accurate I can draw the boat, the more I will learn about the boat design.  

Maybe it does not look like it but I would like to help you. If you do not find what you want on the Internet I could draw a lines plan, strictly following your instructions, which would help you to make the 3D model. Or, if you find something similar on the internet I can adapt it to your needs and fill in the information that you indicate you need for your work. I insist that starting from the shapes of a 10 m boat you can get the shapes of a boat of 14 m, with total accuracy.  

Dolfiman Senior Member

archie1492 said: ↑ I'd like to make the boat drawings accurate for the 14m size. Perhaps one day I will develop this into something worth building full scale. The more accurate I can draw the boat, the more I will learn about the boat design. Click to expand...

Cata 14m with Gene-Hull UE Catamaran 2.3_2018 01 15.ods

Gene-Hull Catamaran 2.3 User Guide_2018 01 16.pdf

Hull for cata 14m with Gene-Hull UE Catamaran 2.3_2018 01 16.pdf

Dolfiman, thanks so much! This is exactly what I was looking for. It's very interesting and probably a bit over my head at this point. I think this should work for modeling the basic hull shape. For the bridge deck and all of the stuff above the hull I can model this with a bit more creativity. Although, I'd like to learn more about understanding the center of gravity for the boat and the proper location of the mast. Are there any rules of thumb about this? Thanks again!  

archie1492 said: ↑ I think this should work for modeling the basic hull shape. Click to expand...

Cata 14m V2 with Gene-Hull UE Catamaran 2.3_2018 01 15.ods

In complement to illustrate this first approach, my good friend Alain did some 3D views here attached of the hull V2 version with Multisurf (using fit for purpose ouput data in section 5. of the above file). To inspire you , some other examples of cata, more sport/day sailer oriented than the Saona 47 : - R/P 45 (Reichel-Pugh) : multihull http://reichel-pugh.com/tag/multihull/ - Dazcat 1295 : in this video, from 1:45 the launch, you can see the hulls from various angles https://www.youtube.com/watch?v=0BZF4Udda5E - SIG 45 (VPLP design) : from 1:20 you can see the winward hull fully lifted ​  

dean 1962 New Member

archie1492 said: ↑ Dear all, I want to create a detailed building information model for a 13 - 15 meter catamaran that is capable of being CNC cut and assembled. I need some help finding plans I can use as a basis of design. Specifically, I need the hull profile information. Section cuts through the hull will give me the ideal contours for a boat of this size. Can someone help? After weeks of searching, I still cannot find these online. For now, this is merely an exercise in my 3d modeling capability. I'd like to share my drawing work with the forum if I can get some assistance to start off. There are future possibilities I am also considering. I'm an experienced Architect & construction designer with a strong background in computer aided design. Once I've modeled the boat in 3d, I would like to flatten the various parts and create plans for the individual boat parts to be CNC cut. I would like to build a small scale model first (1:2o or perhaps 1:10) with the ultimate goal of building the boat full scale. Click to expand...

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Archie, I have been looking to do the same thing. Where are you at on the project? Very interested in hearing all about it. Thanks.  

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Building expertise: our catamaran construction principles

At Outremer every specification has to be precise and consistent with what the naval architect has drawn. During catamaran construction, he or she works in close collaboration with the designers and engineers to reach a harmonious end result.

Safety, reliability, performance, comfort, and pleasure are the key words throughout the design of an Outremer blue water catamaran.

Peace of mind no matter the weather conditions.

An absolute priority for all sailors! We can accept that for racing boats, risks are knowingly taken into account, but for cruising catamarans, a very big safety margin is fundamental. For this reason, the daggerboards are essential to guarantee good upwind sailing, even in difficult situations (storms, rough seas, etc.). We don’t always choose to find ourselves in such situations, but Outremer will bring you back to port, in all conditions.

Resisting the test of time and continuous improvement

Every Outremer will without doubt cover several hundreds of thousands of miles across oceans or around the world during its lifetime and it is crucial that every system is proven and reliable. To achieve this, Outremer takes particular care with the standard of finish, with its choice of technologies and the selection of brands of equipment they install on their boats. What’s more, every year we conduct a survey among all new Outremer owners to help us consistently improve our liveaboard catamaran construction techniques. This feedback is especially important: it allows us to get closer to building the “perfect boat”!

Combining comfort and pleasure of sailing

Multihulls from the Outremer yard are of course, not racing yachts, but they are among the fastest of cruising boats! Performance is both a source of pleasure for any sailor and also an essential safety factor allowing the crew to have more options when facing weather risks, especially single-handed.

Unparalleled quality of life onboard

One of the keys to successful cruising! The quality of life on board depends essentially on comfort at sea. All the elements which go into making an Outremer are combined to achieve an incomparable quality of life with a comfortable interior: more gentle movement allows for quality sleep, no slamming under the bridgedeck, and reduced pitching, leading to good cooking conditions for whoever is in the galley. Silence on board, the absence of any creaking or groaning, so often found on a sailing catamaran, guarantees unrivaled peace and quiet.

Easy sailing and fun for all

Because the pleasure shared between the crew is the guarantee of harmonious life on board during a blue water sailing journey, Outremer takes everyone’s needs into account: skipper, crew, children, guests… Everyone can enjoy 360° visibility, perfect ventilation, and great ergonomics. And of course, the enjoyment of sailing, feeling a boat which goes fast and well, as seen when using the tiller which is available on Outremer boats, an incomparable way to feel a multihull slipping effortlessly through the water!

Loïck Peyron, 4X sponsor: “The point of sailing is the point of departure and the destination. Between the two, the sailing part is fun, of course, but it’s often too long!”

Architecture

Designing the ideal boat

Naval architects translate specifications into lines and volumes:

• Hull designs carefully studied and optimized; long, to carry the required load and reduce forward resistance. Fine hulls demand, in effect, little power to make the move and allow them to maintain high average speeds under way. Not just that, but also to be able to use only one motor when there is no wind, reducing the amount of noise in the hulls when some of the crew are off watch, and also doubling the range under power.
• Windage is limited for maneuvers in port and for better holding at anchor.
• Centering the weight: a very low center of gravity, and weight distribution around that center of gravity – all these unseen elements add to the quality of sailing and reduce pitching movement.
• Fine bows absorb pitching and help produce high levels of comfort under way.
• Daggerboards for sailing to windward, going faster when close-hauled and being able to reach otherwise inaccessible anchorages. Sailing close-hauled on an Outremer catamaran is worthy of the best monohulls, even in the hardest of conditions.

Catamaran construction principles: how are Outremer multihulls made?

The methodology of the Outremer boatyard: putting forward a blend of high-tech technologies and know-how. Blue water cruising programs require significant safety margins: you need to be able to count on your boat in all circumstances!

Even though the philosophy of the yard of is to reduce weight, this must never be done to the detriment of the structure, and our designers are committed to reinforcing the essential areas: the bows are protected by several watertight crash-boxes, the lower part of the hulls are resistant to collision and knocking, the daggerboard wells are indestructible as the daggerboards act as a fuse, making it insubmersible as a result.

Even though modern composites such as those found in sandwich construction are essential materials for saving weight, an Outremer always has the lower part of the hull built in a very thick monolithic laminate: in the event of collision, no structure in sandwich construction could compete with the strength of an Outremer hull. The structure is completely laminated in the hull, and not simply glued on: there is no backing mold interfering with access to any part of the underwater hull, and all the systems remain visible and accessible.

The stiffness of an Outremer catamaran is incomparable

The main bulkheads are of large dimensions, and so are able to take much greater loads than a cruising multihull might encounter. Inserts in carbon fiber, closed-cell foam, isophthalic resins and high-resistance polyester: everything is designed to guarantee your safety for offshore sailing.

For the furnishings, sandwich panels are used to reduce weight, with wood veneer for warmth and aesthetic appearance. The furnishings do not add to the rigidity, and are insulated from the structural parts to reduce unwanted noise, creaks and groans. Aluminum structures support the floors, which don’t squeak either. No more wedged doors or drawers that won’t shut. For the equipment, we choose brands and makes for their quality, their reliability and their suitability with the boat’s program.

An Outremer is designed to be around for over fifty years

Owners change over time, all with ambitious projects and wanting to replace or add certain equipment to their cruising catamaran! In this respect, we apply four golden rules: every part of the boat and every system installed must be documented, be accessible, able to be checked and be replaceable.

Today, more than three million miles have been sailed by our multihulls on every ocean, most of them cruising tropical seas, though many have seen extreme conditions, ranging from Alaska to Patagonia. The huge amount of experience accumulated by Outremer has allowed us to refine and consolidate our principles of catamaran construction.

Catamaran Design Guide

Spectacular sunsets in the Pacific turn the horizon into a brilliant spectrum of gold and orange colors.

Copyright © 2006, 2008 by Gregor Tarjan. Click here for terms of use.

performance, yet desire high daily averages and passage times, which should be as short as possible. When choosing a large multihull, sailors look, above all else, for safety and comfort, long before the consideration for flat-out speed comes into the discussion. Nevertheless, performance is a highly important design consideration. No catamaran sailor wants to sail slower than a same length ballasted keelboat. Below are some EVALUATION & COEFFICIENTS useful coefficients, which will help compare monohulls and multihulls objectively.

Bruce Number (BN)

below "Indigo," a magnificent Wormwood 70, sailing in sparkling Caribbean waters.

Various multihull characteristics and design features can be expressed in mathematical formulas. Their results are crucial and will give prospective owners a basis of comparison between different types of catamarans. These numbers are important, as they eliminate ambiguity and clearly display various advantages or concessions of a design, which would be hard to quantify any other way. Mathematical coefficients not only will provide insight into a boat's performance in varying conditions, they also reflect concerns about loads to be carried safely, speed and stability.

We have already mentioned the Displacement/Length and Sail Area/ Displacement ratio in our chapter on Multihull Advantages, illustrating the point of a multihull's efficiency. Let's look at some other coefficients that give us an indication of a boat's performance.

What is performance and how do we really measure it? Most people who buy a cruising catamaran are not really interested in racing

The Bruce Number is very similar to the Sail Area to Displacement ratio although the formula is slightly different. It is the square root of the sail area in feet, divided by the cube root of the boat's displacement in pounds:

SA = upwind sail area (mainsail and 100% jib)

Displ = weight of the boat in pounds

Similar to the Sail Area to Displacement ratio, the higher the coefficient the faster the boat and better is its performance in light air. Typically a BN of 1.1 will be the threshold between fast and more sluggish multihulls. A heavy displacement monohull might have a BN of .7, whereas a modern cruising catamaran shows a BN of 1.3. Offshore multihull racers can have BNs of 2.0 and higher. The BN will also tell us about a catamaran's ability to withstand stronger winds before reefing. A boat with a higher BN is usually overcanvassed in strong conditions and will have to be reefed earlier than one with a lower coefficient.

On the other hand, they will be able to produce more "power" than their counterparts in lighter winds and perform better.

Sail Area to Wetted Surface (SAWS)

SA/WS = Sail Area Wetted Surface Coefficient

SA = upwind sail area

WS = total underwater surface area (hull and appendages)

This formula simply divides the upwind sail area of the boat (mainsail and 100% jib) by the wetted surface. This coefficient will give us a statistical indication of the multihull's lightair performance since in low wind conditions skin friction becomes an important factor. Monohulls can have coefficients of at least 7% more than multihulls.

Hull Fineness Ratio (HFR)

The Hull Fineness Ratio, known as the hull's beam-to-length ratio, is an interesting number. It is derived by simply dividing the waterline length of the hull by the waterline beam of the hull.

Max. WL/Max. Beam WL = Hull Fineness Ratio Max. WL = length of the hull at waterline in ft. Max. Beam WL = beam of the hull at the waterline in feet.

Monohulls, when compared to multihulls, have low hull/fineness ratios. In Part 1 of this

book, discussing "Efficiency," we saw that ballasted keelboats are limited to Archimedes' principle of hull speed (1.34 x VWL). Multihulls do not have these theoretical barriers, because their hulls are narrower.

The thinner the hull the faster it will be able to travel through the water. But, attention! It will also carry less unless you are on a mega cat. Typically, a 40' cruising catamaran's HFR will range from 8:1 to 10:1. Dennis Conner's above While sailing under spinnaker and experiencing virtually no roll at all, guests will always find a comfortable spot to relax on the foredeck, an impossibility on a monohull.

There are various methods of calculating the transverse stability of a catamaran. One of the simplest and most utilized techniques is establishing a relationship between the height of the Center of Effort (CE), displacement, beam and sail area. Multihull designer, James Wharram added safety factors of 20% to compensate for gusts and the dynamic environment of the ocean. Another method is described in the text below.

Multihull Stability & Capsizing Moment d - Displacement (kg) x half beam (m) max ~ Sail Area (sq m) x Height of Center of Effort (m)

P max = maximum pressure exerted onto sails

Multihull Stability & Capsizing Moment

height of sailplan CE

half overall beam (half hull beam)

racing cat "Stars and Stripes" had a 16:1 HFR. Of course, the larger the boat, the narrower the hulls will become in comparison to its length. For example, the HFR of a 100' luxury catamaran may be 12:1, providing it with a high speed potential. However, monohulls can show HFRs of 3:1, though the comparison is complicated as their angle of heel affects the measurement.

One has to be very careful when analyzing the Hull Fineness Ratio of a cruising catamaran, because other factors such as the actual shape of the hull cross sections (Prismatic Coefficient, PC) can throw the analysis off balance. Go-fast sailors like to think that fine hulls are always fast. That is not necessarily true because a slim hull could have a large underwater volume, thus slowing it down. Consequently, a wide waterline-beam hull could have less drag than a narrower one. It could have a shallow underbody (low PC), which would be beneficial to load carrying (Pounds Per Inch Immersion Number, PPI) and early surfing characteristics at speed.

Stability Coefficient (SC)

This mathematical formula has been devised by the distinguished catamaran designer and sailor James Wharram and his team. This coefficient analyzes a multihull's ability (in a static environment) to resist capsizing due to wind.

( 0.682 VW x (.5 Boa) ) x .555 = CW .00178 x SA x h

W = Wind speed, apparent, in mph CW = Critical Wind Speed to capsize in mph SA = upwind sail area in sq ft. h = height of Center of Effort (CE) of total sail area

Boa = Beam overall

This formula will tell us how much wind it will take to overturn our multihull. By instinct we will know that a catamaran with a wide stance and a conservative sail plan will be very stable offshore. The SC formula will inevitably illustrate that a wider beamed catamaran with a tall sail plan will be as resistant to wind induced capsize as a short-rigged, narrower boat. This is not so if one considers the chaotic environment of waves and the real world of heavy weather sailing. It is interesting to note that a wide beamed boat (regardless of the SC) is more resistant to capsize in seas due to the effects of a higher moment of inertia. In an open-ocean environment, which is everything but static, the SC formula has little meaning. Nevertheless, it serves as a good basis to evaluate stability as a factor of wind force.

below When the wind suddenly comes up, all that is needed is a couple of turns on the jib furler to quickly reduce the headsail size. The catamaran will hardly sail any slower, but feel more comfortable.

Wide hulls and a large overall beam will increase the overall righting moment of a catamaran. A word of caution: Excessive beam will reduce the fore and aft stability. Designers strive to compromise hull fineness ratios, place heavy weights towards the CG (Center of Gravity), and engineer hull and overall beam to achieve a seaworthy balance, which is safe, yet provides ample liveaboard accommodations.

Catamaran Stability Considerations

Diagonal Stability & Beam-to-Length Ratio (BLR)

Stability of a multihull, or the resistance to capsize, should be seen as three components. Athwartship Stability is one well-publicized type and the one often talked about. The other much more important types are Fore and Aft and Diagonal Stability. Fore and aft stability is established by the relationship between the boat's waterline length and the distance between the hull centerlines. It will reflect the catamaran's resistance to tripping. This relationship should be in the vicinity of 39% to 42%. For a seaworthy cruising multihull it is important maintain the proper ratio between length and beam, which, in turn, balances equal amounts of athwartship with diagonal stability. The goal should be to prevent the possibility of a sudden discrepancy of powers between fore and aft and sideways resistance. Most of today's multihulls keep these two component forces in equilibrium, making them extremely seakindly and safe.

Some early design multihulls were very narrow, partly due to the material limitations of that time. But things have changed. Contemporary composite construction allows designers to build wider boats without compromising stiffness. Production catamarans of today have a wide stance and have the benefit of greater safety margins in gusty wind conditions than their older cousins. Multihulls are sophisticated structures and true modern miracles. They provide a more comfortable ride and more interior room. Thanks to modern materials they weigh less and perform better than catamarans built only 10 years ago.

Some catamarans, especially production boats, which are very popular in the charter fleets, are growing wider by the year. The businesses who rent these beamy monsters adore them. Lots of room plus open decks are ideal for clients and the bigger (wider) the boat, the more paying guests can share the fees. But there certainly is a limit as to how wide is too wide. Extreme beam can be dangerous. It can lead to instability fore and aft and to excessive bridgedeck slamming, as the relative distance from the bridge deck to the water will decrease with an increase in width. A vessel with excessive beam might seem stable athwartships, but it will compromise overall stability.

We know that multihulls can, in extreme cases of seamanship error in wild storms, be thrown over from any side - front, back and beam-on. The best examples of this phenomenon are racing multihulls, especially Formula 1 trimarans, which have fine hulls for speed and huge sailplans to provide driving power. They are initially extremely stable athwartships (High Beam-to-Length Ratio), but have a tendency to become unstable fore and aft. They will surf down waves and reach a point where the power of the sails, and speed, will exceed the ability to keep the bows out of the water and the boat will pitchpole. This is the reason why catamaran designers usually draw their multihulls with a Beam-to-Length relationship of between 50% and 55%. The longer the vessel the lower that percentage becomes.

I am currently involved in the "Gemini" project, which presents an example. It very well might become the world's largest sailing catamaran. She will have an overall length of 145 feet, yet her beam will "only" be 54.4'.

Please, don't worry. "Gemini" will not be tender and tip over in the slightest breeze. On the contrary, this monster will be one of the most stable craft afloat, although the beam-to-length relationship is only 37%. The relatively low beam-to-length ratio also involves the fact that the boat would be too heavy and building costs would be prohibitive if she were to have a standard 52% BL relationship. Most importantly, could you imagine turning a 75-foot-wide boat?

above Asymmetric spinnakers on furlers are great inventions. They add instant sail area, yet can be doused in a matter of seconds when the wind picks up strength.

above Although this Edel 35 was a good-looking and popular catamaran, it suffered from excessive bridgedeck pounding, which was caused by only several inches of clearance between the saloon's underwing and the sea.

Obviously there is a sweet spot in the beam vs. stability question. Designing too beamy a boat will also necessitate more freeboard to preserve bridgedeck clearance which, in turn, will increase windage and complicate maneuvering. Unless sophisticated aramid construction methods are utilized, more beam will also add more weight and stress to the structure. Adding more mass will, to a certain point, help make the boat more stable, but where do we stop? Is it better to add weight or width to make a boat stiffer? Of course, both characteristics are interrelated as a beamier boat normally is also heavier. Just adding weight to a catamaran simply to make her more stable will not pay off. Consequently, making a boat too wide might increase living space yet it will also burden the structure, require a beefier manufacture, and yield an even heavier boat. Needless to say, a boat which is too wide will also create practical restrictions such as maneuvering, the ability to haul the vessel and much higher building costs.

Beam has a great effect on bridgedeck clearance, which is one of the most vital characteristics of a good cruising catamaran. As standard practice, the well-known rule of 1" of bridgedeck clearance for each foot of beam was a safe way to prevent excessive wave slap. The wider the beam the more the relationship changes and the necessary height of 1" per foot of beam needs to be increased to 1.3" or more. In the extreme case of overly square boats, that number will have to be closer to 1.8" per foot of beam. This will have a negative effect on any seaworthy multihull that has a bridgedeck saloon. The wide beam will necessitate a high cabin sole to remain a safe distance from the waterline. In order to provide standing headroom, the coachroof might be higher than practical, which could result in a boxy, high-windage multihull. Not only will this be unattractive, but also raise the Center of Gravity (CG) which really should be kept as low as possible.

More overall beam on the other hand (given that there is still sufficient bridgedeck height) has a less known benefit, as it reduces the possibility of hull-wave interference, which is particularly important for fast designs. The wave interaction between the hulls can lead to additional resistance, and especially in an agitated sea state, the formation of wave crests can pound the bridge deck. Most early narrow-beamed catamarans suffered from this phenomenon,

Ultimately, a boat's design has a major influence on its ability to stand against the forces of nature, and to keep occupants safe. Manufacturing excessively wide catamarans is like trying to market monohulls with super deep-draft keels. Both are totally impractical. We designers have to make sensible compromises and learn from past experiences of what has worked at sea by balancing the benefits of a wide boat with its disadvantages.

below This narrow-hulled Outremer 64 Light has completed her third circumnavigation with the same owners. Note the smooth underwing clearance, lacking any protrusions or steps.

"A great cape, for us, can't be expressed in latitude and longitude alone. A great cape has a soul, with very soft, very violent shadows and colors. A soul as smooth as a child's, and as hard as a criminal's. And that is why we go!"

~ Bernard Moitessier

Dinghies, windsurfers and every imaginable type of water toy can be stored conveniently on large catamarans and easily launched from the wide transom steps for shore-side pleasures. Note the twin life rafts located in special compartments on the massive aft crossbeam.

Continue reading here: Hull

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• Heavy Weather Tactics - Catamarans Guide

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What length should a stub keel be to waterline length on a catamaran?

There is no set rule for the length of a stub keel on a catamaran in relation to its waterline length. The length of the stub keel will depend on various factors, such as the size and design of the catamaran, intended use, and specific requirements of the boat builder. Generally, the stub keel on a catamaran is designed to provide stability and improve sailing performance, so it is important to consult with a naval architect or boat designer to determine the appropriate length for a specific catamaran.

What is a 16 passenger catarmarn like?

A 16-passenger catamaran is a type of boat or vessel specifically designed to carry 16 people comfortably. Catamarans are multihull boats with two parallel hulls, which are connected by a deck or a structure. They offer stability, speed, and efficiency in the water. A 16-passenger catamaran can vary in size and design, but generally, it will have enough seating or lounge areas for all passengers. It may have indoor cabins with beds or seating areas, as well as outdoor spaces for relaxation or socializing. These boats often come equipped with amenities such as bathrooms, kitchens or galleys for meals, and sometimes even entertainment systems. The catamaran's size can influence its specific features. Some catamarans are designed for day trips or shorter excursions, while others are built for longer journeys or overnight accommodations. Additionally, they can be used for various purposes, such as whale watching, diving trips, ferry services, or private charters. Overall, a 16-passenger catamaran provides a comfortable and stable platform for small groups or gatherings, allowing passengers to enjoy the beauty of the water while ensuring safety and comfort.

Is the catamaran hull floor always on the waterline?

No, the hull floor of a catamaran is not always on the waterline. The design of a catamaran allows for the hulls to be elevated above the waterline, reducing drag and increasing speed. The position of the hulls in relation to the waterline can vary depending on factors such as the weight distribution, load, and sailing conditions.

How close to a catamarans design reefing points should you go?

You should always be careful when approaching reefing points on a catamaran and stay as far away as possible. Generally, you should aim to stay at least 10 meters away.

What keel to length ratio for catamarans?

The keel-to-length ratio for catamarans typically ranges from 0.1 to 0.25.

Is 70% length to beam ok for a catAMARAN?

Yes, it is generally accepted that a catamaran should have a length to beam ratio of between approximately 6:1 and 8:1. Therefore, a 70% length to beam ratio would be within an acceptable range.

What is the waterline length to baem ratio of a typical cruising catamarans?

This ratio will vary depending on the type and size of the catamaran. Generally, the ratio should be between 1:1.5 and 1:2.5, with 1:2 being the most common.

MIKE WALLER 

Yacht design.

WE SPECIALIZE IN BOAT PLANS FOR AMATEUR BUILDERS

We provide stock boat plans for both monohull and multihull sailing vessels, including sailing skiffs and sharpies. Our designs mainly feature timber construction, in plywood or cedar strip plank composite construction, using the W.E.S.T. system (wood epoxy saturation technique). Our designs are intended mainly as cruising boats, although several have done well in racing. All designs are suitable for amateur boat builders.

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Boat is well up to expectations. Have experienced some heavy weather and are impressed by the stable ride especially to windward. Judy can still use the vacuum cleaner at 30 knots +  She is alo impressed by her washing machine and dishwasher not to mention the deep freeze !!  Large Rig but easily handled by 2 persons.

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	Ed Horstman designed TRIMARAN and CATAMARAN plans are drawn for the first time builder. Plans are concise and clearly drawn so the builder can easily follow each building step. Designs are continuously updated with your input and new ideas. Plans include full size patterns to 63'. The larger TRI's and CAT's have full radius hulls.With no lofting you build right away. The DESIGNER'S book TRIMARAN and CATAMARAN CONSTRUCTION is part of the plans (over 21') and covers all phases of construction. Plans are leased to build ONE boat, NO time limit. Tri-Star designs are proven designs, sailing the seven seas since 1964. Free consultation is provided to the original non-professional builder till he or she is sailing the seven seas. All boats may be built with flared hulls, with the exception of the TRI 25, TRI 26MT, CAT 27PC and the CAT 27. A DESIGN FEE for customer modifications to stock plans. TRI-STAR 18 Study Plans 20.00 TRI-STAR 18 Plans 175.00 TRI-STAR 24 Tri-star 25. TRI-STAR 25 Study Plans $40.00 Add To Cart TRI-STAR 25 Plans $550.00 Add To Cart TRI-STAR 26 MT Tri-star 27-9, tri-star 31, tri-star 31 cm. TRI-STAR 31CM Study Plans $40.00 Add To Cart TRI-STAR 31CM Plans $600.00 Add To Cart TRI-STAR 32 XR TRI-STAR 32XR Study Plans $40.00 Add To Cart TRI-STAR 32XR Plans $600.00 Add To Cart TRI-STAR 35 TRI-STAR 35 Study Plans $ 40.00 Add To Cart TRI-STAR 35 Plans $ 650.00 Add To Cart TRI-STAR 35 XR TRI-STAR 35 XR Study Plans $40.00 Add To Cart TRI-STAR 35 XR Plans $700.00 Add To Cart TRI-STAR 36 Tri-star 37 xrc. TRI-STAR 37 XRC Study Plans $ 40.00 Add To Cart TRI-STAR 37 XRC Plans $ 800.00 Add To Cart TRI-STAR 38 / 39 Tri-star 40 lw, tri-star 42, tri-star 43 xrc, tri-star 43 mc, tri-star 44 lw, tri-star 45, tri-star 49, tri-star 50, tri-star 51 mc, tri-star 54, tri-star 60 / 63, tri-star 65, tri-star 80, tri-star 104. Email us for availability and prices Aluminum Boat Plans Aluminum Catamarans SPECMAR Aluminum Catamaran Hulls are either symmetrical or asymmetrical in design. A symmetrical hull consists of two basic V-bottom hull structures. Asymmetrical hulls are basically a monohaul craft split down the middle and spread apart. A fOIL assisted cat has a lifting foil between the two hulls to increase performance. One of the advantages of our aluminum catamaran is high initial stability. Prices shown on this website are for plans and for a one time use of CAD cutting files. Share full article Advertisement How to Charter a Boat If you want to sail off into the sunset, at least temporarily, you need to understand how to get aboard first. By Lauren Sloss This time of year, it’s an inevitable thought: Life would be that much better out on the water. Specifically, on a boat. 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In contrast, Matt Blake, 38, a software engineer based in Oakland, Calif., was eager to grow his sailing experience during a recent trip to La Paz, Mexico, with his fiancée. He hired a captain but made clear that the captain was there to help and teach. Where do you want to go? “Do you want something that’s more culturally oriented? Nature oriented? An adventure trip?” asked Mary Curry, the voyage product director of Adventure Life , which offers small group tours and private trips on land and on water around the world. That answer can determine your destination. Popular cruising grounds include the Caribbean, Croatia, Alaska and French Polynesia, but the sky — or the sea — is really the limit. For help narrowing your focus, travel advisers often have relationships with charter companies or outfits around the world, and sailing publications offer recommendations. Kyla Malkani, who has had experience with charters working as a destination wedding planner, recommends consulting the concierge of waterfront hotels, particularly for short-term or day rentals. “A lot of times they will have either their own fleet or they will have some sort of connection at a dock,” said Ms. Malkani, 37, who is based in Washington, D.C., and is currently working as a content creator and freelance event planner. What kind of boat? Where you want to travel and for how long will likely determine the kinds of boats that are available to you. Crucial at this point, too, is an understanding of the boat’s layout and amenities. “You definitely want to choose the right kind of boat,” said Ms. Malkani. “If you want more adventure, a sailboat is nice. If you’re looking for a luxury party environment, a yacht is best. And if you’re looking for something smooth, for older people or with kids, a catamaran is great.” David Barclay is a luxury travel adviser who has also chartered boats for his own vacations. “You want to match what the travelers want to what the boat offers,” he said. Perhaps a group of friends might not mind a catamaran with functional but not luxurious marine bathrooms, but a multigenerational group might prefer more high-touch amenities. When should I book? Often, charter trips are once-in-a-lifetime experiences that require a great deal of advanced planning. “You may have a specific place you want to go, or a specific time of year you want to travel,” said Mr. Barclay. “And some places just aren’t good at certain times of year.” Naturally, you don’t want to be at sea in the Caribbean during hurricane season, or in the Mediterranean during winter storms. But you also might want to avoid peak cruising seasons, too. 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Boatsetter , an Airbnb-like platform for boats, is a good resource for last-minute bookings, especially for day trips, and even has an Instant Book option for down-to-the-wire bookings. “If it’s for a special event, or around major holidays, you may want to book a month or two in advance. But for general bookings, you can find options within a week or two,” said Kim Koditek, Boatsetter’s head of brand strategy and communications, of the company’s overnight offerings, which appear on their platform under the luxury yacht charters category . Ms. Malkani has used Boatsetter for some of her charters, most of which have been booked with a specific goal in mind. “I’m a sunset chaser,” she said. “My husband and I just really love being on the water, and we always try to squeeze in some sort of boat day activity when we’re traveling.” For more travel advice, visit our collection of Travel 101 tips and hacks. Come Sail Away Love them or hate them, cruises can provide a unique perspective on travel..  Cruise Ship Surprises: Here are five unexpected features on ships , some of which you hopefully won’t discover on your own.  Icon of the Seas: Our reporter joined thousands of passengers on the inaugural sailing of Royal Caribbean’s Icon of the Seas . The most surprising thing she found? Some actual peace and quiet . Th ree-Year Cruise, Unraveled:  The Life at Sea cruise was supposed to be the ultimate bucket-list experience : 382 port calls over 1,095 days. Here’s why  those who signed up are seeking fraud charges  instead. TikTok’s Favorite New ‘Reality Show’:  People on social media have turned the unwitting passengers of a nine-month world cruise  into  “cast members”  overnight. Dipping Their Toes: Younger generations of travelers are venturing onto ships for the first time . Many are saving money. Cult Cruisers: These devoted cruise fanatics, most of them retirees, have one main goal: to almost never touch dry land . 456 IMAGES Liveaboard catamaran plans Optimising Hull Lines for Performance Free Beach Catamaran Hull Plans Catamaran hull plan Optimising Hull Lines for Performance Catamaran Hull Build VIDEO A Study of a Planing Boat in Regular Waves Sketch To Sea: HH Catamarans Superyacht 8801 Pre-Completion Interior Walkthrough Passenger Catamaran (20m) Nacra 5.7 Catamaran Sailing AZ Un catamaran à énergie solaire à Marseille Proboat Apache Catamaran EP RTR COMMENTS Catamaran Hull Design The most important catamaran design hull shape factor, is the Prismatic Coefficient (Cp). This is a measure of the fullness of the ends of the hull. Instinctively you might think that fine ends would be faster as they would "cut through the water better". But in fact you want a high Cp for high speeds. DIY Cruising Catamaran: Complete Building Guide If you were to build a 40-foot (12.1-meter) catamaran, your cost of materials would range between 20-30% of the total cost. Therefore, for $300,000 total, the boat's materials would range between $60,000 and $90,000. The hull tends to range between 15-35% of the total build. Catamaran Design Formulas T c = 0.57. Here we put B TR = 1.9 to minimize boat resistance (for her size) and get the draft calculation for a canoe body T c (Figure 1). Midship coefficient - C m. C m = A m / T c (x) B WL. We need to estimate a few coefficients of the canoe body. where A m is the maximum cross section area of the hull (Figure 3). Catamaran Construction Newer Lagoon catamarans use polyester and vinylester resins, also infused with balsa cores above the waterline and solid below. Catana. With a carbon fiber inner skin, Catana also uses Twaron aramid fibers in the sandwiched hull over a foam core. Fontaine Pajot. Primary hull construction is resin-infused vinylester with a balsa cored hull and deck. Kurt Hughes Multihull Design Order the Latest Design Portfolio today to see over 85 multihull plans in stock.Besides illustrating my stock designs, for which I sell study plans and full construction plans, it also contains my design philosophy of multihulls; an article on the rapid Cylinder Mold(pdf) or Cylinder-molding (in html) multihull construction; examples of drawing sets; photographs; fact sheets with dimensions ... Catamaran and Trimaran Boat Plans Catamaran & Trimaran Boat Plans from Hartley Boats make it a reality to build your own multihull at home. Build with Plywood or Fibre Glass. 12-35 ft plans. ... There are some unique challenges building a multi-hull sail boat, the extra beam added by each hull for instance can create storage issues while under construction. Hartley boat plans ... Catamaran Stock Plans Catamaran Stock Plans. ... Plans are leased to build ONE boat, NO time limit. Tri-Star designs are proven designs, sailing the seven seas since 1964. Free consultation is provided to the original non-professional builder till he or she is sailing the seven seas. All boats may be built with flared hulls, with the exception of the TRI 25, TRI ... How To Create the Perfect Cruising Catamaran Layout The Prismatic Coefficient (Cp), a measure of how full the ends of the hull get, is the most essential design hull shape factor for any catamaran. A high Cp equals high speeds, although you can still use a lower Cp if you have fine hulls. Nevertheless, the key to a good Catamaran design is a higher Cp for fast sailing. Optimising Hull Lines for Performance A discussion about catamaran hull shapes and how they relate to performance and sea keeping with specific reference to the 33' catamaran Mad Max. ... This is the rocker line isolated from the lines plan above (in blue) and and the red line shows a more moderate rocker line that achieves the same buoyancy and maintains the centre of buoyancy in ... 15' Coastal Power Cat Plans for this Coastal Power Cat include the following sheets. 15' Plywood " Flat Cat". Tunnel hull. Center console. L.O.A 15'-6" x Beam 6'-11´x Draft 10" 4.72M. 2.11M. ... The hull is a "false" catamaran with a tunnel that's partially immersed. A built-in "venturi" minimizes the wetted surface once the Flat Cat gets up ... Our Catamaran Build Kits Our construction plans and kits are sold with 100% professional boatbuilder support via phone and email, any time you're unsure or just need a second opinion, we're here. ... The first step to building your dream catamaran begins with a strongback - this is a square frame used to position the temporary frames that will be used to form the ... Catamaran Construction with a DuFlex Kit Step 1. Kit Design. Work with us to finalise the details of the design you have chosen including any design options or additional modules to be included in the kit. We will determine the laminates, the number of panels required for each laminate, create the cutting files and prepare a quote for the kit if it is not already priced. How to Build a Catamaran Boat? (Step-by-Step Guide) Start by laying the fiberglass over the frame of the boat. Make sure to cut the fiberglass to size and overlap the edges for a strong seal. Once the fiberglass is in place, mix the epoxy and begin to apply it. It is important to apply the epoxy in a thin, even layer to ensure a proper seal. Open Source 13-15m Catamaran Plans archie1492 Junior Member. Dear all, I want to create a detailed building information model for a 13 - 15 meter catamaran that is capable of being CNC cut and assembled. I need some help finding plans I can use as a basis of design. Specifically, I need the hull profile information. Section cuts through the hull will give me the ideal contours ... Catamaran construction principles: design, know-how The stiffness of an Outremer catamaran is incomparable. The main bulkheads are of large dimensions, and so are able to take much greater loads than a cruising multihull might encounter. Inserts in carbon fiber, closed-cell foam, isophthalic resins and high-resistance polyester: everything is designed to guarantee your safety for offshore sailing. Catamaran Design Guide By instinct we will know that a catamaran with a wide stance and a conservative sail plan will be very stable offshore. The SC formula will inevitably illustrate that a wider beamed catamaran with a tall sail plan will be as resistant to wind induced capsize as a short-rigged, narrower boat. ... No, the hull floor of a catamaran is not always ... Plans For Catamarans And Monohulls We provide stock boat plans for both monohull and multihull sailing vessels, including sailing skiffs and sharpies. Our designs mainly feature timber construction, in plywood or cedar strip plank composite construction, using the W.E.S.T. system (wood epoxy saturation technique). Our designs are intended mainly as cruising boats, although ... Easy to build catamaran for amateur boat builders Easy to build catamaran ideal for inexperienced amateur boat builders. This easy to build catamaran is intended to allow anyone, no matter their background, to build a modern cruising multihull with a thrilling performance and an appealing design with a small budget. The Bora-Bora 28 has a very practical interior lay-out with accommodation ... Bruce Roberts, CATAMARAN boat plans, CATAMARAN boat building POWER CATAMARAN PLANS and KITS, CATAMARAN PLANS , Bruce Roberts WEB SITE offers catamaran boat plans and catamaran boat kits for fiberglasss and aluminum boat designs, cut to size CATAMARAN kits, part built boats or complete boats. Bruce Roberts Yacht Designs offer boat building project management arrangements for boats built overseas at affordable prices. Plans & Kits DUO 800 The DUO 800 is the biggest of my a-symmetrical catamarans which can be built on any flat surface, a floor or big table. ... Decrease Quantity of Strike 16 Main Hull Only Plans Download Increase Quantity of Strike 16 Main Hull Only Plans Download. Price: $150.00. Subtotal: Add to Cart. Add to Cart. Wingmaran 15 Study Plans Download ... Trimaran Plans The DESIGNER'S book TRIMARAN and CATAMARAN CONSTRUCTION is part of the plans (over 21') and covers all phases of construction. Plans are leased to build ONE boat, NO time limit. Tri-Star designs are proven designs, sailing the seven seas since 1964. Free consultation is provided to the original non-professional builder till he or she is sailing ... Home Step by step how to build a Catamaran. DIY small boat plans. Wooden boat plans. Videos of how I built a Catamaran - 40 ft. A 3 year. Home boat building. Step by step how to build a Catamaran. ... Do you want one hull or two? Deciding between a catamaran and a monohull is a big decision and one worth... Going fast - in small boats - hull ... Aluminum Catamarans 45 FT Catamaran Workboat (1740) 44' 7" / 13.59 m. 17' 7" / 5.36 m. 16,100 lbs / 7,303 kg. 15,750*. SPECMAR Catamaran Hulls are either symmetrical or asymmetrical in design. A symmetrical hull consists of two basic V-bottom hull structures. Asymmetrical hulls are basically a monohaul craft split down the middle and spread apart. JMSE When a ship sails in shallow water, it will show different hydrodynamic performance from that in deep water due to the limitations of water depth. The shallow water effect may lead to hull sinkage and trim, increasing the risk of bottoming or collision. In this study, a new design scheme of a shallow-water seismic survey vessel is proposed to solve the problems of traditional seismic survey ... How to Charter a Boat This time of year, it's an inevitable thought: Life would be that much better out on the water. Specifically, on a boat. Even if you have neither a boat nor boating experience, it's never been ... catamaran gulet powerboat riverboat sailboat trimaran yacht