tornado catamaran building plans

Tornado Catamaran Building Instructions From 1979

Introduction: Tornado Catamaran Building Instructions From 1979

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Step 1: Tornado Catamaran Olympic Trials 1967 AYRS Report

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How to (with pictures) build a Mosquito catamaran in tortured ply

Discussion in ' Multihulls ' started by Corley , Jul 16, 2012 .

Corley epoxy coated

Found this great write up on building a mosquito catamaran in tortured ply on the Victorian Mosquito Catamaran Association site. Might be a good reference for someone who wants to build a tortured ply catamaran be it a mosquito, tornado or A class. The attachment has some tortured ply plans for an early A class. There are also plans for "Houlton" tornado in tortured ply available on the web. http://home.vicnet.net.au/~mosquito/documents/building.php The Gougeon Brothers on Boat Construction also has a section on tortured ply construction it's available free at the following link in .pdf form. http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook%20061205.pdf Here are the building instructions to the early Jerry Houlton Tornado plan. http://bulsailing.com/images/content/85/houlton-tornado-plans.pdf and the tornado plans from thebeachcats.com http://www.thebeachcats.com/pictures/?g2_itemId=11015  

Attached Files:

Combined%20PaoPao%206%20DesignA Class tortured ply design.pdf

Quite large cats and tris can be built with the tortured ply method and Malcolm Tennant designed and made plans available for several. Obviously many of the regulars on the forum will know about all this but I thought since there are new visitors to the site all the time it might be interesting to put up some links to resources and plans relating to the method. Here is a link to the redshift plans. http://www.tennantdesign.co.nz/index.php?page=red-shift Some of the New Zealand 8.5 multis built with this method have remained competitive over many years John Teztelaff's cat comes to mind as does the earlier incarnation of the trimaran Timberwolf which If I recall correctly was built with tortured or stressed ply construction. The other famous trimaran built using tortured ply method is the Gougeons Adagio. Many on this forum have a more detailed knowledge than I on these boats but I hope this will assist new members in some preliminary knowledge and information so they can consider building with this method.  

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November 30, 1999 by Sail1Design Editor Leave a Comment

The Tornado was designed in the autumn of 1967 by Rodney March from England, with help from Terry Pierce, and Reg White, specifically for the purpose of being the new Olympic Catamaran, which was to be selected by the IYRU in an Olympic Catamaran Trials. The boat was developed mainly in Brightlingsea, England.

International Status was granted to the Tornado as a result of its outright winning of the IYRU Trials held in England. The next step, adding the Catamaran event to the Olympic program, occurred two years later, with the result that the first Catamaran event, sailed in 1976 in Canada, was sailed in the Tornado. The Tornado is an outstanding example of a class that was designed specifically for Olympic competition that has become a successful International class on its own merits.

2000 Olympic Silver Medalists: Darren Bundock and John Forbes (AUS)The Tornado has since remained unchallenged as the ultimate one-design catamaran. With its modern, stylish rigging and sleek lines the Tornado is quick to catch the eye of any water-drawn on-looker as it speeds across harbors, lakes, and oceans in over 30 countries around the world. With its ability to reach speeds of 15-18 knots upwind and downwind, and 33+ knots reaching, the Tornado is truly the purists’ speed machine.

Over 4,800 Tornados have been built, with 1,200 class association members worldwide. In 2004, on the Saronikos Gulf in Greece, the Tornado will be sailing in its seventh Olympic Games.

Except for refinements in technical details – improvements in hull, sail, and spar technology, better blocks and lines – the Tornado was unchanged from its beginnings in to the early 90’s. Then, as a result of the increasing popularity of other, smaller catamarans, the Tornado class undertook a major development program in 1993. It was specifically to respond to a request from the IYRU to search for ways to improve the public and media awareness of the sport of yachting, and secondarily to answer the possible challengers to its ‘top cat’ role.

Two weeks of intensive on-the-water testing and development took place in Miami, following considerable discussion and planning. Among the participants were the three medalists from Barcelona as well as designer Reg White. The International Tornado Association spent nearly US$22,000 on the testing, evaluation, reporting, and finally balloting process to the class membership, to find the fairest and best ways to improve the class and the sport in ways acceptable to the sailors.

The testing involved 10 standard and fully competitive Tornados, one boat with a larger main and jib, and two boats with a variety of sailplans that included spinnakers of up to 32 sq. M. Fourteen races were run over the testing period in addition to in-line speed and handling evaluations.

As part of the testing process, new courses were also used, most involving a leeward gate.

Following the testing and regatta, the following points were clear; the larger main/jib combination was only marginally faster than the standard rig, and the spinnaker boats were a surprise, only beating the standard rigs in 2 of the 14 races. The ITA then balloted the class membership, with not only the conclusions but also all of the data and the testing procedure, helping to provide insights to the rig selection process.

A two-thirds majority is required by the class constitution to implement any change; this majority was not reached, the class voting against the expense of a change with no real benefit to sailing. Thus the class retained the same sailplan for the next two Olympics. The course changes, giving the possiblity of better spectator access and greater media coverage, received the votes necessary to be adopted by the class.

The Class felt then that the changes in course, rather than changes in the equipment, would have a greater impact on public awareness and media coverage. Courses are adjustable in length for wind, thus giving a fixed racing time for the event, and the shorter-than-before course also tend to keep the boats closer, making the racing more exciting and more easily viewed. The fixed Start/Finish lines also is a help, allowing faster turn-around times between races. The new course formats have been in use in the World Championship beginning in ’93, and have proven popular with both the sailors and committees, and are continued today.

The issue of changes in the boat were revisited in 1999, when the ISAF decided to have a Multihull Evaluation Trials in France to look at “possible replacements” in the Olympic program for the Tornado. At the time, there were a number of technical changes in materials that allowed for better spinnakers, and better control, and there were then a number of successful double-trapeze plus spinnaker catamarans on the market in the Tornado size range – 20 feet – that were becoming popular.

The Trials were interesting. Except for the custom, all-carbon Marstrom 20, the standard Tornado dominated upwind, beating all production challengers from Hobie, Nacra, Mystere, and others. Only by piling on sail area, plus a spinnaker, were any of the challengers able to beat the Tornado around the race course, and even then the advantage disappeared as the wind increased. But the extra athleticism needed to sail with a double trapeze, and the extra visual interest provided by the spinnakers, was undeniable, and the final outcome was that the ISAF decreed that the equipment for the 2004 Olympics would be the “Tornado with double trapeze and spinnaker”, and left it up to the class how to implement the changes.

The class took an approach that allowed some development and testing, with the goal of keeping crew weight in the same range as with the old rig. The final result, approved by the class in early 2001, were both evolutionary and radical. First was a new mainsail with a flat top and more area, providing more heeling moment to compensate for the double instead of single trapeze and help keep crew weights with the same range. Second, done to clear the trampoline to make spinnaker work possible, was to redesign the jib. The new jib had the same area, but was longer on the luff and shorter on the foot to allow it to be sheeted to the main beam. Interestingly, this change, moving the sail area forward, overcame one of the Tornado’s handicaps, tacking, and made this maneuver much easier. The innovation of a self-tacking jib appeared later in 2001, and was quickly adopted by the entire fleet. Finally, of course, there was the spinnaker, and the class set only size limits, allowing the question of spinnaker handling equipment to be settled on the race course. Again, the advantages of spinnaker launching tubes quickly established themselves, and became a class standard. Interestingly, the two biggest boathandling improvements, the self-tacking jib and the spinnaker tubes, were quickly adopted by the classes below the Tornado, especially the International Formula 18, which was becoming the Tornado trainer for future Olympians.

Class website: http://www.tornado.org/

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Tortured Plywood

The name 'tortured ply' certainly carries a negative ring. But within the limits of the system, that need not be so. The 'torture' comes from the fact that plywood is being bent more than is normal on a small boat and this is more safely achieved with the help of hot water applied to the outer veneers. Because plywood bends more readily at 90 degrees to the grain, it is used in that manner and for each half, the bend at the middle of the boat length will closely resemble a quarter-arc of a circle. So if two flat sheets are first attached together along their long edge, then the combined panel can be curved up to formed a shape close to that of a semicircle.

Claims that this 'torturing' will permit compound curvature are not strictly correct as only the very exterior wood fibres are affected by the damping—but still, such forming can certainly be more extreme that what one commonly experiences with dry plywood.

This semi-circular form lends itself admirably to long slim catamaran hulls, that do not depend on their individual shape for stability. (So by implication, it is therefore NOT suitable for monohull kayaks or canoes that need a tighter, more outboard bilge curve combined with some flat-of-bottom.)

The beam of any catamaran hull intended to be built using tortured ply, will depend on the thickness and type of plywood to be used. One of the most flexible of the marine plys is Okoume or Gaboon, so we will first consider working with that.

So just how far can you bend ply before it fails? Woods vary so much that it's hard to predict exactly, but let's have a shot at it. If we are talking about the recommended okoume marine ply , then from tests, I've found it can be bent in its easiest way (perpendicular to the grain) to a radius of about 300 × t², (with t in inches) and about 500 × t² if bent parallel to the grain.

By soaking the outer skins, I think it would be possible to use these figures for practical use for a tortured ply boat and if we also assume that we're to have a semi-circular section, then the minimum possible beam would equal 600 × t².

So based on the above formula, here is a rough graph of what 'minimum beam' you probably need to accept for a semicircular hull, plotted against each specific thickness of plywood. Each sheet will no doubt vary slightly from these test figures and plys of ⅜" and thicker are likely to be proportionally stiffer as the wetted surfaces will affect a lower percentage of the total plywood thickness, but the graph can still be a good starting point.

However, if you are using denser plywood (such as a meranti or equal), you'd have to increase these figures by about 50% and with Douglas Fir plywood, I am not sure I'd even try it as it splinters too easily and is typically full of surface flaws.

The most famous use of tortured ply is probably its original use to construct hulls for the lightweight 'Tornado' catamaran. In 1979, using 4.5mm ply for the hulls, she outperformed all the other B-class competition, to then be selected as a new Olympic Class - still raced today. Although the method is still used by some today, the actual Olympic boats are now honeycomb sandwiched in graphite. The tortured ply system is more difficult to build to exact dimensions. Here is a picture from the original building manual. More details on how a Tornado hull can be created, can be found online at: www.instructables.com

There is also an interesting article on line about a builders experience making Tornado hulls using tortured ply. http://www.ptwatercraft.com

You'll note that the interior is lightly glassed and a foam/glass stiffener is incorporated into the forward ½ of the hull about ½ way down the hulls. The picture (above left) is from Gougeon's fine boatbuilding book.

The process is to first attached the two side sheets together and then, after soaking the part of the ply requiring the most curve, to curve up the sides with the help of ratchet straps until the deck edge can be fitted into a pre-built deck jig. This will considerably help to control the final shape and once the gunwales and any bulkheads are fitted, the hull is reasonably stable in shape. Once totally dry, the thin skin can be epoxied and even lightly sheathed for additional stability and strength.

Some claims have been made that tortured ply hulls have poor shape and 'plunge through waves' etc. but this depends on what they are used for and the Tornado example is a proof that some can work very well. The two ends can be very differently formed and that helps considerably to control pitching.

As far as using the system for larger boats, it's seldom been done. One could consider using two layers of thin ply to get a better shape through smaller radii or the chart above indicates that a 5-ft beam hull could be made with 5 ⁄ 16 " ply and if heavily sheathed for strength with FG cloth and added stringers, this could conceivably work for a trimaran main hull—though in such a case, it would be a design more for space than for speed. Depth could be added with an additional strip of ply joined with a 3–4" butt-strap located under a stringer.

• The system is simple, inexpensive and quick.
• The only building frame or jig is really the deck frame.
• Boat section shapes are very limited. The ply will bend to create close to a ½ circle bilge at the stern.
• The ply panel will be under some stress for quite a long time and this can make it more susceptible to damage if further stressed or impacted.
• To help deal with the stress, examples of this concept beyond that of a beach cat, will really require fibreglass sheathing and this will add weight and cost.
• The bow shape is very fine and with some designs, may not give enough buoyancy to resist pitch poling.

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• Sailboat Guide

Tornado Catamaran

Tornado Catamaran is a 20 ′ 0 ″ / 6.1 m catamaran sailboat designed by Reg White and Rodney March and built by Sailcraft Ltd., Marstrom Composite AB, and Windrush Yachts starting in 1966.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

The TORNADO first appeared as winner of the 1967 international “B” class catamaran trials. It was an Olympic class from 1976-2008. The class rules were changed to allow twin trapezes, ‘flat head’ mainsail, and asym. spinnaker.(2004?)

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• Yachting World
• Digital Edition

World’s coolest yachts: Tornado catamaran

• April 20, 2021

We ask top sailors and marine industry gurus to choose the coolest and most innovative yachts of our times. This month, Carolijn Brouwer nominates the Tornado catamaran

“The Tornado catamaran is a really cool boat. It was my introduction to high performance sailing and it had a big influence on me in many ways.

“Once you get a taste for it, there is no way back. Sailing the Tornado opened up different doors for me in my sailing career,” says Carolijn Brouwer .

The Tornado catamaran was for many years the fastest Olympic sailing class and was the first catamaran to be introduced to the Olympic Games. It was first sailed in the 1976 Olympic Games and saw its last Olympic appearance in 2008.

There was not multihull option for sailing at the Olympic Games in 2012, but the Tornado undoubtedly led the way for the current catamaran class, the Nacra 17, which must be sailed with a female and a male member of the crew.

“Sailing the Tornado is where I got the feel for apparent wind sailing. It’s a pretty big cat in the small boat sailing world with its 20ft length and 10ft width creating decent loads and righting moment.

“Also, the Tornado was the only Open discipline at the Olympic Games but it was extremely male dominated.”

Brouwer helmed for Belgium at the 2008 Games, sailing a Tornado catamaran with crew Sébastien Godefroid. “I hope this showed that being a woman you can compete at a high level and be very competitive against men in a mixed gender configuration – just like the great Paul Elvstrøm did sailing with his daughter.”

Tornado catamaran stats rating:

Top speed: 20 knots LOA: 20ft/6.1m Launched: 1967 Berths: 0 Price: £23,000 Adrenalin factor: 70%

Carolijn Brouwer

A three-time Whitbread/Volvo Ocean Race crew, Carolijn Brouwer is also a three-time Olympian. She was born in the Netherlands and represented the country at the 2000 and 2004 Olympics in first the 470, and then the Europe. She then switched to the Tornado, representing Belgium in 2008, when she finished 12th.

If you enjoyed this….

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DIY Cruising Catamaran: Complete Building Guide

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A brand-new cruising catamaran can set you back a hefty amount of money. However, a DIY cruising catamaran provides a more affordable way to own your own boat. While building a large boat can be an extremely challenging and time-consuming experience, nothing beats the pleasure of bringing your own boat to life. 

To build a DIY cruising catamaran, buy good design plans, determine your budget and find a working space. Next, choose your hull material, buy supplies and start building the mast beam. Build and sheathe the hull, install bulkheads, the interior, and finally, launch the catamaran boat.

In this article, you will find a complete guide to building your own catamaran. You will also find detailed information on why you may want to consider building your catamaran and approximately how much this project would cost. Finally, we will explore the advantages and disadvantages of building a catamaran from scratch.

Why You Might Want To Build Your Own Catamaran

Most people might think that purchasing a used boat to repair and fix it up would be cheaper than a DIY cruising catamaran. But while building your own catamaran could be an enormous undertaking, it also comes with many advantages over buying something used. 

Other than the unique opportunity to create beautiful memories and experiences while cruising, sailing, and exploring beautiful coastlines, there are a number of benefits that come along with the DIY approach.  

Knowing Your Boat

Building your own catamaran provides you with intimate knowledge of your boat. You will know every corner, including where to find every bolt, wire, bulkhead, rib, hose, and support as you installed them yourself. This knowledge will enhance your confidence while at sea since you will have entrusted your life to a boat whose history you are aware of and deeply connected to.

Pride of Ownership

The satisfaction you get from crafting something with your own hands is immense. As a result, the knowledge that you built your boat from scratch will fill you with absolute pride and an immense sense of achievement. Furthermore, as an owner-builder, you get to keep and enjoy the boat for as many years as you wish.

Substantial Cost Savings

Building your catamaran will work out cheaper than buying a new or even gently used boat. Though you will likely require some additional labor since doing some things will require an extra pair of hands, if you are particularly good at DIY, you will save a significant amount of money on labor costs as a whole. 

Freedom To Create Your Own Designs

If you decide to buy a catamaran boat, it might not be easy to find one that meets your unique needs. However, instead of choosing from production boats that bear traditional and outdated designs, you can come up with an ultra-modern design or style for your catamaran. You also get to pick your layout, size, and equipment based on your taste and budget.

Great Learning Experience

Building your own boat will help you pick up numerous skills that will come in handy later when sailing your boat. As much as you might still require an expert to help you with specialized skills like carpentry or wiring, your new skills will serve you well. This will also be beneficial when it comes to your boat’s maintenance and fixing things for yourself. 

What To Look For in Catamaran Boat Designs

When deciding on the type of catamaran boat to build, you may want to choose a design that’s simple and easy to build. This is because doing so will allow you to spend a shorter time building the boat. 

You also need to have a set of requirements to guide you in choosing your design or what you might call an ideal cruising catamaran wish list. This is essential because, ultimately, you want to build a boat that offers outstanding qualities such as:

• Delivers good speed
• Affordable to own and operate
• Agile, strong, and easy to maintain
• Has a high resistance to capsizing
• Great for sailing and cruising
• Delivers a comfortable and easy motion underway
• Good handling ability and high performance under sail
• User-friendly embarking and disembarking
• Provides ample living and accommodation space 
• Presents a reasonable resale value

It’s worth noting that, in general, catamaran boats tend to offer a fair resale value mainly because of scarcity and the high price accorded to production models. So, if you build a well-constructed catamaran, you are bound to get a return that’s much higher than the cost of materials upon resale.

It’s also good to consider whether the design you settle on is from an established designer. This is significant because documentation of the building process is just as valuable when it comes to selling the boat.

How Much Would It Cost To Build Your Own Catamaran?

The cost of building your cruising catamaran will depend heavily on the size of the boat you plan to build and the skills you bring to the table. To give you an idea of probable costs, a professionally built 40 foot (12.1 m) long cruising catamaran could go for up to $300,000. 

Though building it yourself will undoubtedly be cheaper, most DIY boatbuilders tend to underestimate the expected costs. Your final costs should cover not only the cost of material and equipment but also the labor and time it would take to come up with the final product. 

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. Again, this depends on the finish and furniture.

But before you even start working on the DIY project, you will need to figure out where to do the work. If your home has ample space, then you can opt for a backyard building. But if you live in a small apartment, then you might want to consider renting a small garage at first and then move on to a boatyard later. This is one of the significant costs involved in building your multi-haul.  

What You Will Need

To get a clearer picture of how much the entire project would cost, let’s have a look at what else you will need to purchase.

• Good design plans
• Working space
• Ground tackle
• Matting and roving
• Equipment such as the engine, windows, rudders, deck fittings, mast, and rigging

In addition to the above, you also need to install plumbing and electricals. You may also want to consider going electric rather than using diesel. Not only will this drastically reduce your maintenance costs, but you get to use the regenerated power for all of your housing needs while sailing. 

Some catamaran boat designs help you save costs by advocating the use of less expensive corpus materials. Most of the material goes directly into making the boat, which means there is hardly any wastage on vacuum bagging . With this method, there are few molds and temporal building forms and fewer fillers to grind off as waste. All these factors reduce the time and cost it takes to build your catamaran boat.

That said, building a boat of any kind is a huge financial undertaking. As such, you still need to have the financial ability to keep building; otherwise, your project will stall or take much longer than anticipated. Instead of enjoying yourself and making memories cruising to faraway lands, you might end up spending all your time building a seemingly never-ending boat.

To reiterate, this project is more of a labor of love, given that it involves a tremendous amount of manual work. Calculating an hourly rate on the time spent building the boat and adding this cost to that of materials may make it seem a very pricey exercise. However, it is vital to understand that your time matters, and every hour you spend working for “free” should be included. 

With that in mind, you need to ensure that you are fully devoted to the boat construction project and are sure you want to do it before you begin. Stopping halfway because it seems like too much work would be incredibly costly.

How To Build a Catamaran

When it comes to building a cruising catamaran, you have 3 main options:

• You can buy an old boat and refurbish it.
• Purchase a bare hull plus deck molding for a home-boat building.
• Start from scratch and build everything, including the hull, on your own. 

As mentioned above, renovating an existing boat may end up being more costly than starting from scratch. To build a catamaran boat from scratch, follow the below step-by-step guide.

Prepare the Essentials

Before you jump into such a large project, there are several important aspects to consider:

• Buy your plans from an established catamaran designer. You can also get inexpensive, easy-to-build catamaran designs online.
• Get access to a large working space or build a shed . Depending on your climate, you may need to opt for climate control to avoid an excess of moisture in humid areas. 
• Decide on your choice of hull material. This could be fiberglass, aluminum, steel, wood, or ferroconcrete. 
• Start working on a bill of materials estimate. Include everything that you think you need to get a better idea of the initial costs.

Build the Mast Beam

Using wood and epoxy, cut and glue together the pieces of wood that will form the mast beam. Most of the work at this stage can occur in a garage since it involves building small parts. Still, the work could take up to 4 months, so be prepared to put in long hours.

Build the Boat Hull

Now, it’s time to build the boat’s hull. A catamaran comprises two hulls which are connected with a deck. Below is a short video showing how to build a hull mold:

This work requires a larger facility, so you might need to move out of the garage and into a boatyard. If you don’t have access to a larger workshop, consider building a shed where you can work as you do the construction. Make sure there’s enough room to fit the boat and also allow you to work comfortably. To cover the shed, you can use opaque white tarps. 

Sheathe the Hull

Get all the materials you require for this stage in the construction, such as lots of resin, fiberglass, and foam for use in the hull cores. You’ll also require matting and glass roving to sheath the hull . 

Sheathing helps to make the hull impervious to water and other marine borers. But first, you need to prepare the hull using a rotary sander. To make it as smooth as possible, use light, sweeping strokes. This is a very dusty task so be prepared to wear a facemask and safety goggles. 

Install the Bulkheads

Next is installing the plywood bulkheads . You might need to call in friends to help turn the hulls or use a crane. In this step, you will need to laminate the hull sides on the molded hull panels and bond them above the bulkheads. Ensure the bulkheads are snug and sealed in place.

Construct the Interior Structure

Over the next couple of months, the boat work will involve joining the hulls together with the beams that you had made back in the garage. Then, install the cuddy cabin, decks , and the cockpit . Soon the boat will start to take the shape of a catamaran.

Next, proceed to construct the major structural components such as stairs, hatches, mini-keels, and the interior. Then comes the work of fairing the boat, which is quite labor-intensive. 

Finally, it’s time to apply primer on the catamaran boat and start the paintwork. Before painting the boat, you will need to do additional sanding to finish off the two layers of primer as well as fill all the pinholes. Since it’s a large boat, the catamaran has lots of surface area; thus, the sanding could get extremely exhausting—mentally and physically—at this point.

The painting can take a while, too. The hulls are the easiest to paint, but the topsides, non-skid, as well as masking and prepping could seem never-ending. 

The final stretch involves working on the center bridge deck cabin and other final touches like installing the engines, electricals, and plumbing. This is also the time to fix the rudders, rigging, mast, windows, and deck fittings.

Launch Your Cruising Catamaran

After many months or years of hard work, your cruising catamaran is finally ready to test the waters. After lowering the boat into the water, check carefully in case there are leaks. If none, you can set up the sails and take your catamaran out for your first cruise. 

Below is a short video that takes you through the entire boat-building process:

If you don’t have deep pockets, don’t despair. It’s also possible to build an inexpensive catamaran boat, as shown in this post from the coastal passage .

The Pros of Building a Catamaran

Though it will be a costly endeavor, there are so many things to look forward to should you decide to build your own catamaran:

• It can be lots of fun.
• You get to have a new boat.
• It’s an excellent hobby for DIY enthusiasts.
• The effort is rewarding.
• It offers a great learning experience.
• You get the exact kind of boat you want.
• You can alter building plans and tailor the boat to suit your specific needs.
• It might be cheaper than buying a new boat.

The Cons of Building a Catamaran

Though there are a number of positive aspects to a DIY build, it is just as important to keep in mind that it won’t always be easy:

• Maintenance costs can be quite high.
• It’s both mentally and physically exhausting.
• It might require some technical know-how.
• It can take many months or even years to complete.
• It requires a lot of commitment to finish the DIY project.
• It might be challenging as well as expensive to get insurance.  
• You will spend almost all your free time building the boat. 

DIY Cruising Catamaran Tips and Tricks

If you are new to boat building, it would be a good idea to build a small boat first. This would give you a good indication as to whether you’d enjoy tackling a more extensive project like building a catamaran. Again, if you are the handy type, fixing your own electronics could also save you a significant amount of money. 

Here are more tips and tricks to get the most out of your DIY cruising catamaran:

• Lower your costs. Bring down your costs even further by sourcing for parts and supplies at marine surplus outlets, Craigslist, eBay, or wholesale suppliers. 
• Enhance your resale value. Most home-built boats are not easy to sell since they tend to be too customized. To enhance your resale value, it’s advisable to work with a standard design from a well-established naval architect.
• Follow the design instructions. Make sure to follow the designer’s instructions regarding the type of materials and tools to use during the build to avoid making costly mistakes.
• Maintain your original budget. Avoid any additional customizations once you have started building the boat. Using good plans and sticking to them ensures that your budget doesn’t spiral out of control.

Final Thoughts

Building a catamaran is about more than saving money. It’s fun, exciting, fulfilling, and can be a great learning experience. While it might take many months of back-breaking work, comparative shopping and sourcing for materials will help you save a lot of money. Still, at the end of it all, you’ll have a beautiful catamaran boat, all ready for your first cruising adventure.

However, if you have neither the time nor the energy to build your own catamaran from scratch, refurbishing an existing hull might prove faster and easier. It also works out much cheaper than buying a new boat.

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!

One thought on “ DIY Cruising Catamaran: Complete Building Guide ”

Hello, I am a French Quebecer who is original, imaginative, creative and who finds that all boats and catamarans have a huge flaw and a very big lack of logic. I would have a brand new concept…. I am sending this message to any catamaran creator – designer to make those who have the opportunity and the intelligence to want to know about my innovative idea which will finally upset the market much richer. An idea that will totally change the concept of sailing, navigation and save so much worry!! All I would ask for is a small percentage of each sale of the new product. To be able to make me produce one when I have enough!! It is certain that like that, you just want to tell me: come on Mr. Lessard give us your idea but do not take your word to help me in return! But, if you are the kind of man to have only one word and maybe have a proof of your good faith if the realization of the project would make it… I will be very happy!! Giving it to everyone wouldn’t bother me either…. all I would like is to be able to find flax fiber (too expensive carbon) to be able to try to make my catamaran myself. Because not rich! Have a nice day and looking forward to having a message!!

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Boat specifications, rig and sail specs, contributions, who designed the tornado catamaran.

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What should you do in case of a tornado? Here are ways you can be prepared.

By Adam Thompson

Updated on: August 8, 2024 / 10:30 PM EDT / CBS Baltimore

BALTIMORE -- If a tornado pops up in your neighborhood, you need to be prepared.

A tornado that touches down could cause destruction and injuries to those in its path.

According to the National Weather Service , these are ways to get ready for a tornado:

• Check the weather . Find out if severe weather has a chance to strike in your community. Follow WJZ's First Alert Meteorologists for updated weather details.
• Sign up for App Notifications: If severe weather breaks, the WJZ News app will alert you. Here's how you can download our app . Some phones alert residents of severe weather and tornadoes.
• Prepare an emergency kit. Some of the items you might need are water for drinking and sanitation; food (at least a several-day supply of non-perishable food); battery-powered or hand crank radio and a NOAA Weather Radio with tone alert; flashlight; first aid kit; extra batteries; whistle (to signal for help) 
• Create a Communications Plan : Have a family plan that includes an emergency meeting place and related information. If you live in a mobile home or home without a basement, identify a nearby safe building you can get too quickly, such as a church or family member.
• Pick a safe room in your home, such as a basement, storm cellar, or an interior room on the lowest floor with no windows. 
• Practice Your Plan:  Conduct a family severe thunderstorm drill regularly so everyone knows what to do if a tornado is approaching. Make sure all members of your family know to go there when tornado warnings are issued. Don't forget pets if time allows.
• Prepare Your Home:  Consider having your safe room reinforced. You can find plans for reinforcing an interior room to provide better protection on the  Federal Emergency Management Agency  website.
• Help Your Neighbor : Encourage your loved ones to prepare for the possibility of tornadoes. Take CPR training so you can help if someone is hurt.

During a tornado

When a tornado strikes, here are ways to stay safe, according to the National Weather Service.

• Stay Weather-Ready : Continue to listen to local news or a NOAA Weather Radio to stay updated about tornado watches and warnings.
• At Your House : If you are in a tornado warning, go to your basement, safe room, or an interior room away from windows. Don't forget pets if time allows.
• At Your Workplace or School : Follow your tornado drill and proceed to your tornado shelter location quickly and calmly. Stay away from windows and do not go to large open rooms such as cafeterias, gymnasiums, or auditoriums.
• Outside : Seek shelter inside a sturdy building immediately if a tornado is approaching. Sheds and storage facilities are not safe. Neither is a mobile home or tent.  If you have time, get to a safe building.
• In a vehicle : Being in a vehicle during a tornado is not safe. The best course of action is to drive to the closest shelter. If you are unable to make it to a safe shelter, either get down in your car and cover your head, or abandon your car and seek shelter in a low-lying area such as a ditch or ravine.

Tornado aftermath 

After a tornado strikes, according to the National Weather Service, here's what you can do:

• Stay Informed:  Continue to watch or follow the WJZ First Alert Weather Team. Multiple rounds of thunderstorms capable of producing tornadoes are possible during severe weather outbreaks.
• Contact Your Family and Loved Ones : Let your family and close friends know that you're OK so they can help spread the word. Text messages or social media are more reliable forms of communication than phone calls.
• Assess the Damage:  After the threat of tornadoes has ended, check to see if your property has been damaged. When walking through storm damage, wear long pants, a long-sleeved shirt, and sturdy shoes. Contact local authorities if you see power lines down. Stay out of damaged buildings. Be aware of insurance scammers if your property has been damaged.
• Help Your Neighbor : If you come across people that are injured and you are properly trained, provide first aid to victims if needed until emergency response teams arrive.

Watch or warning?

What's the difference between a tornado watch and a tornado warning?

The National Weather Service breaks down these three alerts:

Tornado Watch: Be Prepared!   Tornadoes are possible in and near the watch area. Review and discuss your emergency plans, take inventory of your supplies and check your safe room. Be ready to act quickly if a warning is issued or you suspect a tornado is approaching. Acting early helps to save lives! Watches are issued by the Storm Prediction Center for counties where tornadoes may occur. The watch area is typically large, covering numerous counties or even states.

Tornado Warning: Take Action!  A tornado has been sighted or indicated by weather radar. There is imminent danger to life and property. Move to an interior room on the lowest floor of a sturdy building. Avoid windows. If in a mobile home, a vehicle, or outdoors, move to the closest substantial shelter and protect yourself from flying debris. Warnings are issued by your local forecast office. Warnings typically encompass a much smaller area (around the size of a city or small county) that may be impacted by a tornado identified by a forecaster on radar or by a trained spotter/law enforcement who is watching the storm.

Tornado Emergency: Seek Shelter Immediately!  A tornado emergency is the National Weather Service's highest alert level. It is issued when a violent tornado has touched down in the watch area. There is a severe threat to human life and property, with catastrophic damage confirmed. Immediately seek refuge in the safest location possible. Call friends and family who are within the watch area to ensure they are aware of the situation. If you see a tornado approaching, do not attempt to outrun it in a vehicle; shelter in place. Once safe, be sure to monitor your local forecast for the latest updates.

Adam Thompson is a digital content producer for CBS Baltimore.

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