diy trimaran sailboat

24 Foot Sailing Trimaran

Introduction: 24 Foot Sailing Trimaran

Step 1: Beaching After the Maiden Voyage

Step 2: Cartopping

Step 3: Or on a Trailer

Step 4: Inspiration

Step 5: Cut and Paste Catamaran Hulls Together End-to-end

Step 6: Thinning the Edge

Step 7: Jigging It Up

Step 8: Glassing

Step 9: Rough Fairing

Step 10: Rapid Fairing

Step 11: Glazing and Finish Sanding

Step 12: High Build Sanding Primer

Step 13: Outrigger Floats

Step 14: Float Blocks

Step 15: Cutting Curved Grooves With a Tablesaw

Step 16: Wooden Shoes

Step 17: More Wooden Shoe Cobbling

Step 18: Hot Spring Break

Step 19: Lashing It All Together

Step 20: Carry It to the Beach

Step 21: Please Return!

Step 22: Farewell Hugs

Step 23: Raising the Sail

Step 24: Launching!

Step 25: So Far So Good

Step 26: What's Going to Happen?

Step 27: Sailing and Landing

I TRI’D – A Self-Designed 18-foot DIY Trimaran

by Small Tri Guy | Oct 4, 2013 | Self-built Small Trimarans , Small Tri Info - All , Small Trimaran Videos | 4 comments

I TRI’D is a self-designed 18-foot DIY trimaran by sailor Mick Milne. He built this sailboat himself after researching lots of small tris and then using using “HULLS” software to produce dimensions for the panels.

The building technique is “stitch and glue” plywood — with the main hull oversheathed with two layers of fiberglass and epoxy. And the outriggers slide in on aluminum beams to allow trailering . It looks pretty good.

Mick learned all this stuff as he went along. But the best part is that he thinks it sails just fine.

Mick said the build took about 16 months in his spare time. This time frame was mainly driven by the weather, however, as the building took place outdoors in the UK, which, according to Mick, had one of wettest winters in years.

The first launch of Mick’s DIY trimaran was last October. What a day that must have been for him.

Great job Mick …. terrific! Thanks so much for sharing the story of your project (and photos) with us here. ( PS – Love the name of your boat too :-)

………………………….

I TRI’D – 18-foot DIY Trimaran by Mick Milne I have sailed for many years, mainly dinghies and small cats, though also a limited amount of coastal sailing in UK and around Denmark. I have never really lived on the coast so sailing as regularly as I would wish has always been a challenge.

Drawing plan for the I TRID Trimaran

A bit more research led me to view that a Tri fitted all the requirements I was looking for:

• Sailing reasonably flat
• Shallow draft
• Reasonable pace
• Trailerable – as long as it folds somehow

The more I looked, the more I got hooked, and I am one of those guys who once something gets under my skin I have to do it.

I spent a lot of time looking at designs and think there are some great Tri’s out there, but I like the problem solving aspect of designing something. I bought and read your book, “ More Small Trimarans, ” and noted the variety of different approaches, ranging from fully qualified and experienced designers to those who “just learnt as they went along”; that was enough inspiration for me to start my own.

First ama hull being built

The only real frustration was the weather. All the build was outside and I spend too much time removing and recovering the boat. If I build another (I suspect I will) it will definitely be under cover.

Main trimaran hull with crossbeam fittings

The small trimaran begins taking shape

First sail fitting with mainsail and jib from a Fireball Dinghy

I definitely expect to do some more modifications in the future. I am not a boat designer and there are things that are not right first time. The seating areas slide in, which I thought would help with the trailing width, but it all increases the setup time. I am going to raise them by about 1 inch , which will allow the outriggers to slide underneath without unlocking various pins etc. Also, I never really designed in an adequate system for mounting an outboard, currently fitted to the sliders it is secure but poorly positioned. I will change this when I amend the seats.

Blue deck paint on this small tri

Launch Day!

Sailing Cardiff Bay

To date, I’ve primarily sailed I TRI’D mainly around Cardiff in Wales. There were also a couple of trips into the Bristol Channel when conditions were favourable. The boat was planned for relatively calm coastal waters, with the expectation that in a few years we will move to the South Coast of England, near Poole, which has a very large natural harbour, with lots only accessible with a shallow draft, and easy access to get further along the coast.

Under sail with her tramps

Smaller trimaran moored with the big boats

Update 10-07-13: Mick sent me the following YouTube video featuring I TRI’D …

___________________________________________________________

Fantastic job Mick!

I’d love to see some more photos, or video of you sailing. I’m also fascinated by the reasons for people’s design choices. Why did you decide to design your own? Why 18 foot? Do you stand on the hull, or is there a floor? What sort of lee-board did you build? Is there a photo? What’s wrong with the outboard position? How long does it take to rig and launch?

Robin, thanks for your interest.

I have a video but am having problems uploading it, not my area of expertise but I will persevere, hopefully I will have that complete in the next couple of days, I will also provide more photos.

Why my own design – I think I covered that partially in the notes but in essence I think I just like to understand how things work and also I like doing things to see if they do work, and I suppose experience has shown me you can do most things if you try.

Why 18ft – I certainly wanted something I sat in rather than sat on, but had also read in many places the advice not to build a boat bigger than you need. Once I started designing 18ft provided enough space to seat two easily, four at a push, and provided enough displacement. I did sketch out some 16ft designs but they just seemed to be too small.

There is a floor, simply 18mm plywood , raised about 4-6 in from the hull base, this seemed to make sense rather than walking on the hull. Surprisingly there are no pictures but I will take some and post them.

The leeboard is simply plywood sheet shaped, but is already showing signs of stress. I am busy reinforcing a hardwood centreboard (with epoxy and fibreglass)which I will use to replace the plywood. I got most of the ideas for the leeboard from Frank Smoot’s excellent website which has featured several times on this blog. His explanations and points, such as that shifting a leeboard to change the CLR, really helped. There are some photos showing the leeboard which I will post.

The issue with the outboard position is the mounting bracket, not the outboard itself. As the slider mountings are round, and close together, I have had to modify the outboard bracket, the bracket obscures access to the slider locking pin and also applies enough pressure to the mounts to restrict free movement of the sliders. This means I am continually slackening or tightening the bracket , or removing it. It is just not a good piece of work. If I was designing the same boat again I would fix a wooden square bar 4-6 inches behind the slider mounts to provide easy location of a standard outboard bracket.

Rigging and launch takes around an hour though part of that is due to the launch site I use. Good launch sites are rare in UK and it is a busy site. I have to rig the mast, the jib , outboard, and seats at a trailer area, and then having reversed onto the ramp extend the outriggers and tighten the tramps, then launch. I then normally rig the main on the water. Part of the work to modify seats, outboard mount and a few other small tweaks is to reduce this time, though I do think rigging the boat is part of the experience so I would not want to have no rigging to undertake.

I hope all that that helps answer your queries and I will put together some more photographs showing some of the detail, and hopefully that video.

Love it, Mick. I’m always excited when any bold venture sets out to, not only build, but design their own trimaran. I’m on maybe my 10th “home brew” tri now, and each one has been not only a blast to build and sail, but a real education as well. My latest (a 19-footer) is probably my best so far. Set-up time was always an issue for me, too, which is why I ended up with a folding design and an unstayed mast with the 128 sf sail furled around it. My designs are shaped by the places I sail (shallow) and by the fact that I always beach launch. 18′ is probably the perfect length for a tri you can launch, rig, and sail alone. Your boat looks great, and I’m delighted that my leeboard info was helpful. Couple of questions, if I may: What does she weigh in at, all up? How much sail are you carrying? Have you had a chance to speed test with a GPS yet? All my boats have hit 14 mph (white knuckling it, for sure!), but I haven’t hit 15 yet. I think I will, though, with my new vertical batten sail. I’d be happy to email you some photos, if you like. Also, I now use solid lumber for my rudder and leeboards, covered in 4 oz glass. They last much better that way (I got tired of having to constantly repair them). Again, excellent job! And I liked the video as well – mainly because you kept the camera moving and we got to see most all of the boat. Cheers, “Trimaran” Frank

Hello Mick,

Congratulations for your boat ! I’m very interested in your 18 ft trimaran because i have the same project. I have some questions : Is there any drift ? where it is ? The seats are fixed under the tubes, that ‘s it ? is it a self draining background in the cockpit or not ? Did you purchase specific sails or you pick up them from an other boat, witch one ? what is the the mainsail area ? what is the weight of your boat ? You designed your boat with what software ?

Thank you for your reply Best regards x.lemaire

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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

Review of nine small, folding day-trimarans (2010)

by mike waters n.a.

As much as I like the basic concept of Jim's new boat, there are a couple of aspects that I need to mention. To put a light rig from a Hobie 16 on a boat that is FAR heavier and more stable than the boat for which it was originally designed, might prove too much for this mast, especially since the shrouds are more inboard than normal—so raising the mast compression. Normally, a Hobie would just 'go over' and so relieve the load—but not this beamy 800 lb twenty-footer! Also, the too-typical, puny 4-oz sail cloth of a regular Hobie 16 sail, is hardly man enough for this job. It's certainly a low cost start up solution and we've all admired Jim for his support to those with lesser means, but I think any builder should plan on something more substantial to be a better match for this cruiser. Finally, as the ama looks to be quite substantial in volume (guessing about 800 lbs buoyancy?), I have some concern for the strength of the single plank akas (cross beams) that act as swing arms for folding, should the builder decide to choose regular construction lumber. Sooner or later, someone will push this boat hard enough to bury an ama and that's a LOT of leverage on those arms, even if they are cleverly designed to act like huge flexible wooden leaf springs. But without seeing the details, I can only suggest that some good laminated material might be in order for these parts and perhaps Jim's plans already call for that or even some added carbon here as well. But I like the general concept and even though the boat will be no speedster, it's a design that can give a young couple on a small budget, a lot of weekend pleasure provided the conditions are within what the rig and swing arms can take.

• This particular Performance Index is simply a product of the principal things that affect multihull performance (LOA × BOA × Sail Area) all divided by the listed Weight. By taking the square root of this value, you then get a figure that very roughly reflects speed for comparison purposes. Yes, I agree there are a lot of factors NOT taken into account with this crude approximation, but the base figures used are easy to find and at least the general trend is indicated—and quite fairly so I believe.

TRIKALA 19 The Trikala 19 is from the board of imaginative designer Kurt Hughes. This boat was actually in production for a while in Spain but since then, a few have also been built by amateurs. A couple reportedly even cruised the Mediterranean in one! This is a boat design that always frustrated me—perhaps wrongly so.

For me as a designer, the looks of a boat are almost as important as its performance and the Trikala looks quite stunning from the bow, with its long fine entry and streamlined deck lines. But then, as it opens out to encompass a very wide cockpit aft, it always appeared to me that something distracted the designer or he just lost interest, as the view from the stern quarter is not so elegant. It's no doubt practical but it's a shame that its wonderful efficient appearance from the bow could not in some way be maintained at the stern. But with that very personal comment aside, this is an interesting boat with no doubt a good performance. It would be a particularly interesting boat to build for someone wanting to learn about composite construction with a larger boat in mind 'down the road', as the Trikala is lightly built of foam core under fibreglass skins and would therefore provide a good learning experience. The boat does not fold in a conventional way but like some other small designs by Kurt, uses a sliding system with tubular akas, the port ones, sliding into tubes with Teflon runners behind the starboard ones—so the two sides are not exactly symmetrical—a factor that some potential buyers find disturbing, though the difference is purely cosmetic. (The larger 7 m, L7 by Mike Leneman, also uses a similar sliding system – though in this case he uses fiberglass channels—see my REPORT on SMALL TRIMARANS for more on the L7, available through my website.)

W17 This design of mine was created during 2009 and completed in 2010.  It's hard to review your own boat designs without being accused of inevitable bias, so I will simply tell you about it and point out the features I've incorporated and why.  However, time has now shown [2020] it's as good as I had hoped and expected her to be.

This is a primarily a boat 'to just enjoy sailing in'. She's designed to be comfortable, way drier than average, fast and efficient and is just at home on a weekend camping cruise as on the circuit.   With several boats now [2020] having each sailed and cruised over 1000 miles and with open sea passages of up to 60 miles safely accomplished, she is certainly proving very capable in experienced hands, employing intelligent sail reduction when things get rough.   Her seemingly simple hull forms give a very high efficiency and she has proven quiet and dry through a chop and with her wing mast and unique ama shape, shows an unusual ability to climb to windward with minimal leeway.   [Following an independent test and review by Wooden Boat Mag., I was asked to explain why the W17 performed so well with such simple shapes and my reply to this was published in the prestigious Professional Boatbuilding magazine #169 .. and is available to read on this website under 'Published Articles'].    

Sailing this boat is indeed a magical experience and dozens of boats are now (2020 update) being built in over 30 countries.   She's a little more time-consuming to build than others her size, but numerous owners have since dubbed her, 'The Miata of the Seas' .      For them, a few more hours is well worth the effect and this boat will take you to a whole new level above any production boat of this size out there .... and also cost you less.

Comparison Chart  (created in 2010)

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Simple Exercise On A DIY Foiler Trimaran

Discussion in ' Multihulls ' started by yigitozturk , Nov 12, 2017 .

yigitozturk Junior Member

Hi, First of all I thank you all for this platform which is a great source for us amateur sailors. I am sailing for six years on different boats for recreational purposes and some little sweet racing. But I would to like to inform you that I have no claim on being a great sailor neither a boat builder. Just a humble architect and the grandson of a carpenter. I am planning to build an i550 and bought plans for it lately, and start researching on glue and stitch method. Meanwhile got overdosed with trimarans (They are everywhere when you are searching for s&g) and one day saw the Broomstick of Mr. Doug Halsey. It was an eye-opening moment for me. I read a lot especially here in this forum about hydrodynamics and current foiling tech and decided to give it a try. I never see a foiler here in Turkey and local sources are really limited. In the end I sketched a tri with my limited knowledge, learned from here and there, tried to design it as simple as possible. Simple form, no rocker, no detailed chin, easy and cheap to build are the key words. For sails, I am planning to use two second hand windsurf sails, rest of it is s&g and some aluminium here and there and used rigging from the workshop of our local marina. I don't claim any originality or rights on anything on the design. I have basic understanding of boat building and how foils works (NACA profiles, how lift generated, etc.) thanks to you people and some boat-designer friends will help me to calculate the draft, waterline and displacement if this makes any sense at all. Just looking forward to hear your valuable ideas and comments. They will be appreciated. Best regards, Yiğit.  

UpOnStands Senior Member

Sweet --Welcome to forum. reminds me of the Hobie Trifoiler in some ways. Like the foils, not the fastest but so practical -- except for launching. Your intention is to rotate the foils around the cross beams? Believe the masts will need stays. Trifoiler used a horizontal beam with wire diagonals.  

upchurchmr Senior Member

Put some rocker and shape in your hulls. Hydrofoil boats have to be good boats before the speed at which they lift off, or they might never get going. You will also waste any speed you get when you try to tack.  

OzFred Senior Member

The centre of effort should be roughly over the centre of lateral resistance. In this boat, it's way forward to the extent it will likely be impossible to steer even before it starts foiling. Move the masts back (look at the trifoiler in profile). You're also giving up about half the righting moment by having the centre of lift only half way out on the cross beams. I think the floats are much, much bigger than they need to be (unless you're going ocean racing…).  

OzFred said: ↑ The centre of effort should be roughly over the centre of lateral resistance. In this boat, it's way forward to the extent it will likely be impossible to steer even before it starts foiling. Move the masts back (look at the trifoiler in profile). Click to expand...

Hi, Thank you for your critics, it is really nice to have some feedback from you people. Trifoiler is a great example, I learned a lot by reading about it. It is a shame that we don't have it in here. But it is way professional for me and my motives. I tried my best to apply the principles you mentioned in to my model. About the foils, distance between is extended further away but I don't know if it is enough for a clear run way for both of the foils. Here is wFoil 18, the close foils doesn't seem much of a problem. Maybe because it is a powerboat. I am planning to build the foils and the beam that binds them as a single structure. So both of those will be carrying all the load and in the end of the day it can be dismantled and stored away by taking away the body and floats. About the launch, I think it will be easy to use some temporary rollers or even some fixed ones under the foils and make this an amphibious-tri. I hope it makes sense. And here are the revised design, looking forward to hear more.  

Doug Lord Flight Ready

Yigitozturk, have you seen the Rave V? Here is a thread about it? Rave V Foiling Trimaran. https://www.boatdesign.net/threads/rave-v-foiling-trimaran.52050/  

Doug Lord said: ↑ Yigitozturk, have you seen the Rave V? Here is a thread about it? Rave V Foiling Trimaran. https://www.boatdesign.net/threads/rave-v-foiling-trimaran.52050/ Click to expand...

Believe your outboard stays are not effective as they are too vertical. Use the horizontal compression member between the masts as trifolier used. The motorized foiler appears to have the aft stays much outboard of the fwd foils so they do not encounter the disturbed wake of the fwd foils. oh, and lose the aft foils and replace with a single foil on the rudder. Should reduce your drag considerably and make tacking easier.  

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Hi again, Thanks again for your kind comment. I was reading and researching a lot lately about multi-hulls. As being an extra amateur boat builder and a good follower of 'less is more' I told myself, maybe I was making things harder than they need to be. This led me to consider a beach-cat like catamaran instead of a trimaran. Building time and cost will be roughly half of the later idea and by reducing the materials and using simple bolt and nut connections.I will be able to do more adjustments and follow a trial and error method ( I am not expecting the vehicle to be last forever, it is mostly for fun and science). In conclusion, I tried my best the keep the principles you people thought me here and simplify it further more. Also I am wondering about which foil profile will be suitable for this kind of project? A simple, straight back air-foil kind or a NACA 0012 like with some angle of attack? Here are the sketches, looking forward for your comments. Best, Yiğit.  

super cheap, simple, dirty: kayak > trimaran

Simple multi chine catamaran

simple amas for canoe-tri

Tough Akas and simple hatches.... Proa WHY NOT?

Simple Info!

Simple idea, kinda.

easy, fast to build multihull with simple rig

Best simple 30' cruising cat

Keeping it simple. 16' overnighter

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Discovery 20 Trimaran

See  Discovery 21 .

The Discovery 20 trimaran is a fast, fun daysailer with the potential to be a camper/cruiser for the adventurous. The D 20 design has been updated as an exciting and powerful new daysailer. It is available as a kit or a complete boat. This design is intended for enjoyable day sailing, although there is space below deck for camping gear. There is a 7' by 7' cockpit that is roomy for 4. You sit upright, with a backrest, not sprawled on a trampoline. My 75 year old mother-in-law found the boat very comfortable. The D-20 is quite fast; the all up weight of the boat is 527 pounds. She utilizes a daggerboard, a rotating aluminum mast and streamlined crossbeams. Construction is wood/epoxy/glass composite.

I really never appreciated how fast the Discovey is until about 10 years after she was designed when I raced mine in a Wednesday night yacht club series against a new Newick 24' trimaran (longer, wider, taller rig, new laminate sails). The other boat was sailed by a very experienced sailor and I was expecting to get my butt kicked. During the first upwind leg (in about 8 knots breeze) the Discovery 20 blew everything away, including a fleet of Etchells. I was so impressed I hove to at the weather mark and waited for the other tri to catch up so that I could get a better comparison on the down wind leg (he had a spinnaker I didn't). As expected, I lost some ground here but not really that much, and I was able to get it all back on the next upwind leg.

Design Archive

• Atlantic 50
• Atlantic 46
• Atlantic 48
• Atlantic 55
• Atlantic 42
• Buzzards Bay 34
• Juniper, Juniper II
• Hammerhead 34
• Hammerhead 54
• Explorer 44
• Sky Hook 39
• Discovery 20
• Superior 54
• Charter Cat 65

6 Best Trailerable Trimarans For Bluewater and Coastal Sailing

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Having a boat costs a lot of money, even when you are not using it, marina fees, etc. And once it is in the water most sailors never go very far from their “home marina” and sailing will be somewhat restricted. However, what if you could fold your trimaran and put it on a trailer, store it at your house, and go to a new sailing spot the next time?

Here are 6 of the best trailerable trimaran:

• The Dragonfly series
• Corsair Series
• Windrider 17

Choosing the best trailerable trimaran (a multi-hull with three “hulls”) will depend on crucial factors like speed, durability, design, and ease of transportation. This article is here to help you get started with your research and hopefully help you on the way towards your dream boat!

Table of Contents

Cruising Trimarans That Can Be Transported

Cruising boats are made for multiday sailing either on the coast of your favorite sailing area or full-out blue-water ocean crossings. Extended living should be a priority in these designs.

1. The Dragonfly 25 and 28 (Dragon Fly Series)

Dragonfly is in the business of making the “best foldable trimarans on the planet” many would agree with this statement. Dragonfly is known for its commitment to easy trailering and ease of use, shown in designs for the Dragonfly 25 and Dragonfly 28.

The “Swing Wing” system on the linchpins is one of the key features of the dragonfly series. The system’s application makes it possible for the trimaran to narrow its beam as much as 50%.

Attesting to its Scandinavian manufacturing, most parts of the trimaran are made in-house. This guarantees quality and ensures that all used parts are above standard.

You don’t need to look further than the Dragonfly 25. Its centerboard slightly offset to port. Extra space is created in the main hull’s interior with a trunk buried under a settee. Performance-wise, the low drag and narrow hull shape allow the boat to reach blistering speeds.

Dragonfly 28 In Numbers

• Length: 8.75m
• Beam folded: 2.54m
• Max crew: 5-7 people
• Max Speed: 22+knots

Dragonfly 25 In Numbers

• Length: 7.65m
• Beam folded: 2.30m
• Max crew: 4-6 people
• Max Speed: 21+knots

2. Farrier F-22

New Zealand enters the trimaran manufacturing race with this premium sea goer. The vessel comes in two different versions: a performance variation with more horsepower and a full cabin cruising version. 

Compared to the dragon series the F-22 has the biggest allowance for space.

The F-22 is known for being one of the easiest trimarans to fold and load.

The sports version of the F-22 has some really good performance to offer. It has an aggressive spirit: you can mount a sail while leaving plenty of space for the boat’s fine entry and flared forward sections. The build quality is also topnotch—a lasting memorial to a principle that Ian Farrier always worked by: excellence.

Farrier F-22 In Numbers

• Length: 7.0m
• Beam folded: 2.5m
• Max crew: 3-5 people
• Max Speed: 20+knots

3. Corsair Series

This boat series has an exciting history. Farrier created it to promote his trailerable tri concept. However, the series is now independent with a top-class vehicle to its name.

The Corsair 760 is listed as providing some of the best performance and safety benefits to sailors.

Building off the spirit of excellence of the founder, the Corsair 760 has created a boat with comfort and racing potential. The boat can be tricky to handle at first, but it will be a breeze once you get the hang of it.

It is also worth noting that the corsair 37 is the largest trailerable trimaran on the market today.

Daysail Trimarans That Can Be Transported

Boats that are made for dayssailing are usually smaller, cheaper and more easily handled. They are perfect for those looking to enjoy a full day on the water in calm weather, but are usually less suitable for multiday events or rough sea sailing.

4. The Astus Models (20ft, 22.5ft, and 24ft)

If you’re looking for something small but still capable of doing day sailing, this 22.5-foot trimaran is for you. Built for speed and maneuverability, the Astus 22.5 has optional foils to optimize speed.

The modern design, coupled with the spacious interior, can fit up to four beds. Accordingly, this trimaran is suited for family outings. 

The Astus brand specializes in transportable trimarans, worth noting is that some models need a specific trailer whilst the smaller boats use a standard trailer.

5. Weta 14.5

The 2019 Weta trimaran is a 14.5-foot (4.4-meter) trimaran featuring a carbon frame, centerboard, rudder foil, and rudder shock. The hull is made from fiberglass and foam. The Weta is built for strength and speed based on these lightweight materials. 

The 2019 Weta trimaran is easy to sail and is worth considering whether you want to take a quiet sail, race with your friends, or take kids to a sailing lesson. It has a simple design and is easy to set up independently.

The small size makes it more suitable for daysailing in good weather rather than multiday cruising, although more experienced sailors will of course push the limits of this boat.

6. WindRider 17

The 17.4-foot (5.3-meter) WindRider 17 is one of the more versatile trimarans in the market. It packs high performance for a low cost. This trimaran has a light rotating mast to boost performance, and a full-battened mainsail optimizes visibility. 

This sailboat is made from rotomolded polyethylene, which is more durable than fiberglass and demands less maintenance.

The WindRider 17 has a comfortable interior and can fit six adults. This is an ideal choice for social sailing for a couple or a family and friends. It’s easy to ride, and a shallow draft allows easy maneuverability. 

What’s the Largest Trailerable Trimaran?

The largest trailerable trimaran is the Corsair 37 , this multihull is built for single-handed cruising while still maintaining the ability to comfortably seat 6 people.

The Corsair 37 provides comfort, speed, and safety. It also contains just enough space to accommodate amenities like a propane stove, a sink, and other equipment.

The vessel is designed to be a performance cruiser. It features an aluminum rotating wing mast, carbon fiber bowsprit, and premium deck hardware. The corsair can still cut through the water with ease despite its size, putting the wind in your sails.

What Is a Catamaran?

A catamaran is a boat with two hulls (a trimaran has three) connected by a bridge deck. Catamarans usually offer more space than both monohulls and trimarans of the same length. The catamaran is usually somewhat slower than a trimaran but faster than a monohull. They are usually made of fiberglass or carbon fiber.

Catamarans come in all shapes and sizes. You can find straightforward sailing catamarans, perfect for those who are only starting their sailing journey. Larger sailing catamarans have become extremely popular for long-distance sailing.

There are also power catamarans, they have huge diesel-powered engines (sometimes electric) and no sails. Also called “power cats”, these boats can reach 30+kts.

Can a Trimaran Be Trailerable?

As discussed above, some trimarans are possible to put on a trailer and move to another sailing area or to be stored at home. This is usually not possible with catamarans but is sometimes possible with the trimarans that are fitted with foldable amas (the two outer “floats” or “hulls”).

Some trimarans can be trailerable, this is mainly due to the ability to drastically decrease the vessels beam, sometimes as much as 50%. This allows the trailer plus trimaran to be below the legal requirements of the road.

Final Thoughts

It has proven difficult to beat the trimaran in terms of speed. Through the ages, this type of vessel has proven to be immensely enjoyable in all kinds of sailing activities. These can range from sea adventures to waterborne relaxation in your free time.

Trimarans come in various types, foldable, for cruising or racing, etc. However, there is a common factor: many of the small ones are trailerable. This makes them easier to move than most other types of boats.

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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Wow, that was fast! Why trimarans are SO much fun to sail – and how to do it

• Theo Stocker
• February 13, 2024

For their size, trimarans can punch well above their weight in speed, cruising potential and fun. Monohull sailor Theo Stocker gets to grips with how to handle one

Humans tend to gravitate into tribes of like-minded enthusiasts, enjoying the encouragement, support and sense of identity, while often looking askance at others; sailors at motorboaters, cruising sailors at racers, monohull sailors at raft, I mean, multihull sailors, and everyone looks askance at jet-skiers.

Large cruising catamarans (40ft now counts as a small one) are a world apart from monohull sailing, but there’s a sub-tribe of sailors dedicated to life on three hulls and builders such as Dragonfly, Corsair, Farrier, and Astus give them plenty of choice.

I’ve been sailing a 22ft (7m) Astus 22.5 this season, with just enough space for a family of four and a minimum of creature comforts. Thanks to her VPLP-designed hulls and 650kg all-up weight, we can sail upwind at 7-plus knots and downwind at over 10 knots with ease, all on a roughly even keel, while the kids play Duplo down below. It can also be beached and is towable behind a car.

Having, it seems, caught the trimaran bug, I wanted to get better at sailing and handling the boat, but my monohull sailing experience and habits were proving something of a hindrance, so we sought advice from some existing trimaran owners, and well as the UK’s top multihull sailors.

Much of the advice will apply to all multihulls , whether two or three-hulled, while other parts are just for small trimarans. I also found that brushing-up some of my rusty dinghy sailing skills helped get my head around what we were trying to do.

To try out our expert tips we went out sailing to see what difference they made. On the day, we got a solid Force 4-5 southwesterly, averaging 16 knots, but fluctuating between 12 and 20 knots true.

Blasting about on a sporty trimaran is a whole world of fun, but is much calmer than it looks

Trimaran sail trim

One of the biggest differences between a cruising monohull and a multihull is how the mainsail is trimmed. Leech tension on a yacht is often largely controlled by the kicker and the backstay, while the mainsheet sheets the mainsail in and out, predominantly controlling the angle of the boom to the centreline, and there may be a short traveller.

On a mulithull, however, there’s more than enough space for a good, wide traveller. Those who sail on performance monohulls will also be used to this. The sail shape is mainly controlled by the mainsheet, and the traveller then moves the boom towards or away from the centreline.

This is exaggerated on a multihull which has wide shrouds, swept well aft with no backstay, making space for a powerful square-top mainsail with full-length battens. There’s no backstay to bend the mast and flatten what is anyway a pretty rigid mainsail.

The mainsheet purchase creates enough power to control the leech of the square-top mainsail

Depowering a trimaran

Sailing on a monohull, heel and weatherhelm and eventually a broach give loads of warning that you’re pushing too hard. With straight hulls and little heel, those warning signs don’t really apply to multihulls.

In reality, however, there are a host of warning signals that it’s time to back-off; they’re just a bit different. Even then, there’s still a large safety margin before you get close to danger.

By way of reassurance, with the boat powered up on a beat, Hein, from Boats on Wheels, the boat’s owner, stood on the leeward hull and lent on the shrouds. Even as his feet got wet and the wind gusted at the top of Force 4, the boat didn’t bat an eyelid, thanks to the huge buoyancy of the floats.

Even with a person on the leeward float the boat was extremely stable

On the water – sail trim

My first inclination was to point the boat as high upwind as possible, pin the sails in and go for height. Doing that resulted in a not-terrible boat speed of 5-6 knots and a good pointing angle.

Free off by a handful of degrees however, and ease the sails just a smidge, and the speed leapt up to 8-9 knots – over 50% more; a huge increase. So, don’t pinch. If you had a decent chartplotter on board, you could find your optimum speed to angle using velocity made good (VMG).

I was also tempted to pinch in the gusts, but it’s better to hold your course and let the speed increase until the main needs easing.

On the wind, it’s time to get the boat fully powered up

If that’s the case, drop the main down the traveller an inch or two or ease some twist into the mainsail and it makes all the difference in the world, but not so far that the top battens fall away and invert – that really isn’t fast. Push too hard and the boat will slow down, largely from the drag of submerging the leeward float and crossbeams. If you’re still overpowered and the main is luffing, it’s time to reef. Downwind is different, but we’ll get onto that later.

After we put a reef in the main, our boat speeds upwind remained largely the same, and the boat was much happier. I came away feeling reassured that even a little trimaran like this would be pretty difficult to capsize, and there were always plenty of warning signs telling me to take my foot off the pedal a little.

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Tacking and gybing a trimaran

Everyone knows that multihulls don’t tack as well as monohulls. Straight hulls and wide beam don’t lend themselves to turning, especially when coupled with the displacement and fixed keels of big cats. Trimarans are a little easier, with a single central daggerboard to act as a pivot, and one or other of the floats will generally be clear of the water. On the downside, light displacement means that there isn’t much momentum to keep you going through the turn and plenty of windage to stop you.

On a trimaran the central daggerboard helps the boat to turn by providing a central pivot point that catamarans lack

Speed is your friend. Build speed up before the tack to give you as much momentum as possible. The helm needs to steer positively into and through the turn, and if necessary, keep the jib backed on the new windward side to help the bow through the wind. Don’t worry about scrubbing speed off, but you don’t want to get stuck in irons.

When it comes to gybing, speed is again key. The turning bit isn’t going to be an issue as you’ll be scooting along, but the faster you’re going, the less load there will be on the sails. The more you slow down, the more the true wind will pile up.

Trimaran sailing skills

Tacks took a bit of practice. It felt plain wrong to jab the tiller across the boat, slamming a big break on in the water but I ended up putting us through the tacks far too slowly, losing a lot of speed. A more aggressive approach worked better. On the Astus, the traveller was between me and the tiller, so the tiller extension needed to be swung around the stern behind the mainsheet onto the new side.

Similarly, old habits of controlling a gybe needed to be modified. With the asymmetric set, we were planing at well over 10 knots, and the ideal is to stay on the plane. Heading dead downwind and centring the main lead to a more violent manoeuvre than flying into the gybe as fast as possible and, as the boom was never that far out thanks to the apparent wind angle, it didn’t need much extra controlling.

Coming up onto the wind after the gybe helped the asymmetric around the front of the jib and to fill on the new side. Stay too deep and it’ll get blanketed by the main. Once we had built up some apparent wind, we could bear away again.

You’ll be on a course deep downwind before you know it, hitting speeds in the double digits

Downwind in a trimaran

Upwind cruising may be fun in a multihull, but bearing away and going with the wind is what it’s all about. Easily-driven hulls, a generous sailplan and light weight mean you can be up and planing, leaving displacement boats wallowing in your wake.

The big difference comes from apparent wind. If you’re in a boat that can do 15 knots downwind in 20 knots of true wind, the resulting wind angles can really mess with your head.

To get going then, says Brian Thompson, ‘Use those leech tell-tales again when sailing downwind and reaching to set the correct twist through the mainsheet, and use the traveller to set the correct angle of the whole sail to the wind.’

As the wind and your speed builds, bear away and trim the main accordingly.

In theory, you shouldn’t need to ease the traveller at all, but you may need to if you want to sail deep downwind. As the gust fades, you’ll find the boat slows down, so you can come back up towards the wind a little to pick up some more breeze, and then bear away as you accelerate again.

Bear away as the boat accelerates. Your course will be something of a slalom as you look to keep a consistent wind angle

This results in something of a ‘slalom’ course, and will also be accentuated if you’re sailing down waves, but that’s all quite normal for apparent wind sailing. Ultimately, you’re looking for a consistent apparent wind angle, even if the resulting wake isn’t straight.

It’s worth remembering that apparent wind reduces the felt effect of the wind, so you need a sailplan to suit the true, not apparent wind speed.

I found that the boat was more sensitive to having a balanced sailplan and trim downwind than upwind, largely because you’ve got almost double the canvas up, with the bowsprit as an extra lever. When weather helm built, I needed to ease the mainsheet to increase twist to depower so that I could bear away. I must admit, getting the boat balanced, sailing fast and light on the helm at 15 knots was something I came away feeling I needed more practice at.

Reviewing the images, I suspect the asymmetric was sheeted in too hard, with too much twist in the main.

Getting a float fully submerged is when it’s time to back off

On the water

Unfurling the gennaker worked best on a beam reach, giving plenty of airflow over the sail to help it fully unfurl. This was also roughly the fastest point of sail, ideal for getting up some speed for apparent wind sailing. We mostly had the sails set for a close reach, even when we were beyond 120º off the true wind on a broad reach.

It was possible to soak deeper downwind, but lose the apparent wind benefit downwind and our speed dropped off dramatically, prompting us to point a bit higher to find some more speed.

As the boat powered up, it paid to hold a slightly higher angle than I would have done in a monohull for the boat to properly take off and get up into double digit speeds – topping out at 15 knots. Lymington to Cowes would have taken us just half an hour at that speed. It’s easy to give yourself a heck of a beat back!

We were sailing on a pretty flat day, so didn’t have to contend with any waves to speak of. On the recent RTI this is what caused the capsizes of at least two multis, a sobering reminder that you need to sail much more conservatively in lumpier conditions.

The bows want to point downwind, so a stern-first approach works with rather than against the boat

Coming alongside

A 650kg boat with no draught and plenty of windage feels dreadfully skittish when manoeuvring in confined spaces. Straight hulls with no forgiving curves and fragile-looking sharp bows make berthing tricky. You’ve got a couple of advantages on your side, however. In the Astus, the floats are at pontoon height making stepping off easy.

Whether you have an engine in each hull of a cat, or one in the central hull of a tri, there’s also a lot more leverage to play with to turn the boat and drive her on or off the pontoon. A steerable outboard gives you even more options.

If the boat has a lifting keel or daggerboards, put them down if there’s enough depth to give you a pivot and to resist drifting. Think about getting corners onto the pontoon, rather than putting the boat alongside. On tris, you won’t be able to get to the bow to fend off as it’s too narrow. You can rig a fender up forwards on a line, and two fenders are enough on the flat sides.

Steering with the outboard towards the pontoon will drive the stern in more; steer away to drive the bow in more

Offshore wind

Coming onto the pontoon with wind blowing off, it worked well coming in stern first. If there’s a tide running, you’ll want to be heading into the tide, so find a spot down wind and down tide to start your approach so you come in at an angle.

On our first attempt we had a bit of tide under us to start with so we came in at a much steeper angle, almost 90º, although this worked out OK in the end.

The crew could then step ashore, taking a line from the stern quarter round a cleat.

Drive forwards against the line and the bow will obediently drive up towards the pontoon, bringing you flat alongside. Getting off was simple, releasing the bowline, and allowing the bow to swing out the before slipping the stern line.

Coming in astern and stopping upwind of the berth meant the bows blew towards the pontoon far to quickly

Onshore wind

Getting onto and off a pontoon with onshore wind proved rather trickier. On our first attempt we came in stern first. The issue was that once we were just upwind of our desired berth and stopped, we lost steerage and the bow immediately blew off with alarming speed towards the pontoon.

Going ahead would only increase the force of the impact, while going astern only increased the bow’s sideways drift. I managed to back out without smashing the bow, but only just, and ended up awkwardly stern to the wind with the bows pointing at the pontoon.

On our second attempt we came in bows first but having aimed at the berth, I had to motor the stern to leeward to stop the bow hitting, making for a rather forceful coming alongside.

On take three, I came in forwards and began ferry gliding towards the berth early, keeping the bows to windward of the stern. Being able to steer with the outboard meant I could go ahead to keep the bow up, and go astern with the engine pulling the stern down toward the pontoon. In this way, it was possible to come in pretty well controlled and parallel to the berth.

To get out, motoring astern against a bow line pulled the entire boat clear before slipping the line

Leaving was a different proposition all together, as I didn’t want to drag the bow along the pontoon, or to drive hard onto it to spring off. Instead, we rigged a slip-line from the forward cross beam. Going astern against this, and then turning the engine towards the wind, I could pull the stern, and the rest of the boat, out and away from the pontoon.

Keeping power on astern, once we’d reached a decent angle, we slipped the line and went astern, finding steerage way almost at once, with the bow following obediently in our wake with more control than I had anticipated.

Whether the wind is blowing onto, or off the pontoon, you want the engine to be driving or pulling the boat off the pontoon with a line on the corner you are going away from. That way you avoid point-loading fine ends where it’s hard to fender.

You’ll want a bridle to reduce swinging, but keep the pick up lines on the bow as backup

Anchoring and mooring a trimaran

While mooring a catamaran is complicated by the lack of a central bow, things should be simpler on a trimaran, and they are, mostly. Picking up a mooring buoy from the main hull bow with a low freeboard and dropping the pick-up line onto a cleat is easier even than a monohull.

The bow may be narrow, but for any lines that pass through a ring on the buoy, you still need to take it back to the same cleat to avoid chafe. That should be it, but windage from the two extra bows and the lack of keel mean the boat can dance merrily around the mooring buoy in a breeze.

Rig the bridle so the buoy sits to one side to stabilise the boat

In practice, we found that a trimaran benefits from a mooring bridle in the same way that a catamaran does. It can’t be rigged from the floats’ bows, as there are no mooring cleats, so a line passed around the outboard ends of the forward beams gave a pretty good angle, again with long lines passed through the mooring and back to the same side. The main pick-up lines stay as a safety backup.

The other trick is to rig the bridle asymmetrically so that the buoy sits to one side or the other, just enough to not be dead head to wind, making it much more stable in the wind.

On the plus side, the lack of draught or keel means that you’ll nearly always be lying head to wind, so the cockpit remains nice and sheltered whatever the tide’s doing.

We ran out of time on the day to try anchoring, but rigging a bridle, effectively a long snubber to a point on the anchor chain in a similar way wouldn’t be tricky.

If you needed not to swing, or to behave more like deeper boats nearby, hanging a bucket over the stern can help, or there’s always anchoring with a kedge, either out ahead in a V, or in line astern.

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The new "Mini Trimaran" as it is being called (for now) is an evolution of our work in small multihulls over the years. It combines elements of the successful  Expedition Sailing Canoe  and the " kayak trimaran " named 'Spongebob' into a new vessel. Hull #1 was cut out as a CNC kit in July 2020 and is now in the process of going through sea trials. Click here for Construction  Photos of hull #1   You can get a sneak peak of the builders guide here .

Features of hull #1 included a roller furling mainsail and headsail for easy reefing and a boom for superior sail control. For Hull #2 we went back to a non rotating mast with slab reefing and single line reefing instead. The amas retract into the center crossbeams to reduce the overall beam for trailering without having to demount the amas. A stern cockpit with a large kayak style cockpit coaming can be used with a spray skirt. Steering is accomplished with foot pedal controls or a tiller. The boat can also be sailed from the center cockpit and there is optional space to install a hobie mirage drive in the center cockpit. Ample storage for a full expedition load. The center cockpit is flanked by a pair of "wing decks" which are large enough for sleeping aboard with a bivy or cockpit tent. A leeboard is controlled with lines running to the aft cockpit. The hull incorporates an integral spray chine above the water line to increase cockpit comfort while maintaining a narrow waterline beam of 19 1/2" 

Length: 18’ 6” Sailing Beam: 11’ Trailering Beam: 6’ 8-3/4” Working Sail: 100 sqft Optional Spinnaker: 80 sqft Empty weight: ~290lbs Gear/water capacity: 150lbs Full Load Displacement: 620lbs (solo) PPI: 117lbs (pounds per 1” immersion Ama buoyancy: 275lbs 

Above: Hull #1 freshly painted. April 2021

Latest News: Plans and a CNC kit for this design are coming soon. Hull #1 and 2 are currently in testing and prototyping phases and we look forward to improving the design of the rigging and kit for future builders. 

Video from first Sea Trials in Jan. 2021. We were very pleased with the performance and look forward to further testing the rigging and design in preparation for releasing plans and kits for this design. You can note in the video that the boat is being sailed totally empty so the bow rides a bit high. 

Hull #1 made the trip to the 2021 B&B Messabout and we had a chance to test here out. 

Hull #2 was completed and launched in January 2022. Changes to the design include adding some legroom to the aft cabin, and including space for a hobie mirage drive well in the center cockpit. Hull #2 does not have a roller furling mainsail but instead more traditional slab reefing. A Core Sound 17 mainsail is now the primary working sail and a furling code zero is again used for light air and an off the wind boost. 

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