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Garage-Built Hydrofoil Sailing Trimaran

Here is a YouTube video featuring a garage-built hydrofoil trimaran. It was recently posted by a sailor identifying himself as Craig Tuffnell.

The vid’s description on YouTube reads as follows:

“Garage project – prototype hydrofoil trimaran. Sailing in the Marlborough Sounds, New Zealand during January 2014. These are the first trials up on the hydrofoils in light and puffy winds. Great fun, easy to sail and more stable than expected. Still needs a few mods to improve performance. Completely disassembles for transporting on (and in) a car! Takes about 30 minutes to assemble.”

Pretty neat … in a nice breeze … on a flat water surface :-)

We’d love to find out some more about this one. Maybe Craig will see this post and reply.

(Thanks to Tom Williams for sending me the video clip below).

UPDATE 01-22-14: I received the following info, along with some pictures, from Craig — the builder/sailor. He saw this post and offers the following:

kotuku-hydrofoil-trimaran-on-trailerThanks for posting my trimaran. Its certainly had more interest than I thought it would have. It’s called “Kotuku”, the Maori name for the White Heron. I live in Christchurch New Zealand and the video shows me sailing in the Marlborough Sounds.

My goal was to keep it simple and make it easy and fun to sail – a bit of a challenge with hydrofoils, but I think I have come close. The foils are all retractable and there is an adjustable flap on the rudder foil. Unfortunately, I can’t adjust the flap without stopping – something I need to change!

kotuku-hydrofoil-trimaran-on-displayThe hulls are carbon (main hull) and glass (amas) wrapped around wire cut and sanded extruded polystyrene and vacuum bagged. There are plenty of improvements to make, such as replacing the rudder and rudder foil and changing the crossbar to carbon now that I am happy with it.

The nose dive in the video (same incident in both instances) was the only significant crash in 4 days of sailing and I dug in deeper than I should have because I was very slow releasing the main sheet. The good thing was that I didn’t completely pitch-pole. As you can see I’ve tried to keep plenty of buoyancy forward of the mast.

Its been a fun project and many hours in the garage!
— Craig






  1. Hi Everyone

    I thought I should chip in as its my boat (Kotuku). The aim on the project was to build a foiler that was easy to sail and easy to transport – keep it simple.

    The nose dive was the only significant incident in 4 days sailing and was partially due to poor sailing on my part. Once it dug in I didn’t let go of the mains sheet for a while so it went down. But I didn’t completely pitch pole so that was in some ways a success. Where I was sailing is a challenging spot. On my last day of sailing (the cloudy day and the day of the nose dive) the wind came in gusts from the norwest, then the east, I was becalmed for a while and then a southerley all in the space of one hour. Gusts would come from opposing directions!!! I figure if I can sail a foiler there, I can sail it anywhere.

    BTW, the amas are on pivots so do not affect the foil pitch. I also have one fence on the foils, but I’m not sure how well it works yet.

    There are still loads of improvements needed and I appreciate your comments. I have a small flap on the rudder foil, but I cant adjust it easily. I’m still working out the best adjustment for it to have the yacht flying at the best angle. I should make it adjustable while sailing!!! The rudder and rudder foil needs replacing (long story) and I think I have too much power in the main sail too.

    I like the “regular guy’s hot-rod” small boat. In some ways this sums up the project.


    (submitted by Tom Williams…copied from http://www.boatdesign.net/forums/multihulls/small-surface-piercing-trimaran-foiler-49393.html)

  2. Love it! I’d really love to make one of my tris into a foiler one of these days, or better still, build one from scratch. That’s an awesome job for a home-brew builder, Craig. I wish I lived close enough to see it firsthand! One of these days…
    – Frank

  3. Such a fantastic machine. I am really enlightened by this. I liked the duck billed platypus idea of the canoe – easier to catch onto maybe as well on landing ! Best of brilliance developing the dream.

  4. Wonderfull machine… I wish I did it….

    After years fliying with gliders, I came back to an old leisure : sailing…. So, I wanted to mix both in a home build machine.

    I started to develop such a minimalist trimaran foiler with V foils, based on the one of PK of Fred Monsonnec that you can see on the web (http://foils.wordpress.com/2007/04/19/le-pk-de-fred/), exept the choice of the foiling system (V instead of T!!!).

    I made the reduced model 1/5 in order to analyse possible problems. My goal is to get is very easy and fast to mount and sail…. and most of solutions i wanted to implement are on… your boat!!!!

    Some differences : I plan to use a sail of windsurf with cambers (because I have it… and I use it with low winds!!!). The back foil is suppose to get an auto adaptative position of the flight (like moth, but not for the main foil… with a control with the stick).

    I’m testing infusion for the hulls…. but only with fiberglass (cost…). When I’ll be satisfied, I’ll make the real one!

    I’d love to share the problems you faced and to get some more informations with your choices (profil for foil, pictures….).


  5. Yes, this is really a very beautifull and interesting boat.
    I put a link with your video on my blog in March.
    I’m one author of the french blog “Foilers”, and I built many years ago a little trimaran with hydrofoil, PK (thank you Vincent to make reference to my boat !).
    More pictures here: https://foils.wordpress.com/tag/pk/
    I hope you find great pleasure with your boat…
    You probably know Gary Baigent, one master of the foil in NZ, if not I can send you his e-mail.
    Vincent, if you read this message, don’t hesitate to contact me on Foilers…

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