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Design and build your own WW kayak!

design your own kayak Strategies, tools and techniques for designing and building your own kayak.

And, I did it my way :)

After putting my home made whitewater kayaks on display on the Internet ( & “HOX” I’ve gotten lots of questions on how I did it. That’s why I am writing this little manual on how you can do this yourself, hoping that this will inspire more people to give it a try.

I’m sure you have your own ideas on what properties your boat should have and how it is supposed to be designed. A glassfiber construction has the advantage of being lighter and stiffer than plastic boats, although they are more prone to break if you hit rocks with sections that are not designed to flex (e.g. chines and edges). Another benefit of using glass is that it’s easy to repair or redesign the boat as you get new ideas.

I started with drawing the boat I wanted to build using the eminent software “Kayak Foundry” that Ross Liedy has made available for download on his web page .

Sure, it takes a little while to learn how to use and master this program... It was made for designing sea kayaks, but with some tweaking it’s possible to come up with a body suitable for a whitewater playboat. Kayak Foundry can also produce side views and cross sections on any given part of the boat.

design your own kayak

To get you started, here is a little boat I’ve made which you can open with Kayak Foundry and use as a template: wwhomebuilt.yak (Right-click on the link and choose 'Save target as...' to save this file to your computer. You can then open the file with Kayak Foundry. Alternatively, you can download the zipped version of this file by clicking here).

  • First you start to make the “plug” it should have the design you look for.
  • Second you make moulds of the plug (will be negative copies).
  • Third, make your glassfibre boat using the moulds.

The small pictures on the right show one way to do the plug and in the text below is another:

KayakFoundry can draw cross sections at a distance of e.g. 10cm to use as templates for making 10cm thick foam blocks. You can cut blocks of foam with a hot wire or a band saw. Glue all the foam blocks (or thick foam sheets if you like) together using epoxy or any other glue that doesn’t degrade the foam. Do this carefully and you’ll have a good base for making your plug. It’s a good thing to make the foam blocks slightly bigger than your wanted end result as you need to shape chines etc yourself (KayakFoundry has it limitations when it comes to sharp edges).

Now comes the shaping phase and it’s impossible to be too thorough with this. Shape and grind and shape and grind again until you are perfectly happy with your design. When everything looks exactly as you want it to, paint the foam model using a solvent free paint. If you are really satisfied with the finish of your model then you can cast your plug directly on the foam model, if not you can put maybe two layers of polyester plastic on it, putty and then cast.

Attention! If the surface of your plug has the quality of ordinary paint and is REALLY dry you can put two layers of release film on it and don’t bother about waxing it. Instead grind and paint the finished boat using spray paint after removing it from the mould. Ok now we have a plug to use for making the top and bottom moulds of the boat, remember that the moulds needs to be able to be removed from the plug (e.g. think of angles and corners and stuff). Put film on the plug (remember it’s better not to wax it).

  1. Paint one layer of gelcoat (thoroughly)
  2. Paint another layer of gelcoat after about 5 hours.
  3. Put on a layer of glass weave after another 5 hours.
  4. After that let it rest for a day or so then put on 2 layers of glass per day until you are happy (6 layers should be enough for simple moulds).

Now the moulds are done. Take the plug out of the moulds and you can start fabricating your first boat out of the moulds. On my boats I have used 2 layers of 450gram weave on the deck and 3 layers (450 g) on the hull with some reinforcements where needed. It came out at about 13 kgs complete and stiffer than termoplastic boats. Always use at least 2 layers of gelcoat, even if you will paint it afterwards. During 2006 I have paddled my glass fiber boat a lot and prefer it compared to my Dagger Juice 7.1 and my WaveSport T3. It's an excellent surfer, spins well and is really fast for its length! Some guys (not me) loop in it and river running class III-IV is not a problem. It’s very forgiving! I let one of the top freestylers in Sweden try it out and his only complaint was that it was a bit hard to hold it on edge (I will fix this for next year's model ;-)

design your own kayak
On the little wave above ”Hällhole”, Fänforsen, Västerdal River, Sweden.

I will remake/make the next one a little narrower (1cm) and make the hull/deck slightly more rounded. You will be able to see it again here on Playak.

Hogge, Sweden

PS Some boats I designed this way:

design your own kayak
Printed templates in place
design your own kayak
Put on strips of wood to make chines

Bottoms up!
design your own kayak
"The skeleton" is made in plywood.

time to make a cockpit
design your own kayak
Starting to look like something!
design your own kayak
Top side of the plug before casting.
design your own kayak
The inside of the deck mould..

Posted: 6 years 6 months ago by dblanchard #27249
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Anyone in the Seattle area interested in working on a mold, and some boats, with me. I have space and time, but would like a work buddy.

Posted: 7 years 7 months ago by cico0815 #22019
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I know this thread is long gone but I would like to try buidling this boat this summer break and I wonder if I might fit in it! I am 186cm and my weight is 90kg...anyone out there who did already build it and is around my size? Like to hear how the boat feels? :-)

Best regards,

Posted: 8 years 8 months ago by Beaverman #15434
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after 25 kayaks and a few molds, I find nothing the matter with using fillers to get the smoothness one wants for a shape, prior to making a mold from a plug.

as for how to make the cockpit rim, we used to lay out a waxed garden hose and plaster over it to make a cockpit rim mold with fiberglass.

and the earliest back bands I remember were old Army web belts with pads sewn to them by a cobbler, tied in with rockclimbing accessories rope to holes drilled in the seat framing and back walls.
Posted: 8 years 9 months ago by fungidick #15052
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That looks very cool :-)

How did get the outfitting inside? (backrest etc;)
Posted: 9 years 2 months ago by michielv #10775
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Just a thought here: if you don't know where to start, you could take a multiple sides view (top, bottem, side, front, back) of your current fave model and work from there.

BTW: it might even be worhtwile to mix constructions like plywood/epoxy/glass (similar to stitch and glue) for big flat surfaces (ie. the bottom) and shaped foam covered with expoy/glass (sort of like a male mould, you just pop off the glass off the foam) for the curved bits. Then assemble the boat by covering it in a layer of glass with epoxy resin.

Or something like that.
Posted: 9 years 2 months ago by taliesin38 #10767
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That is very cool. We have been looking at building an ocean surf kayak but had not really planned on a river running boat. I'll have to think about that.
Posted: 9 years 2 months ago by nitrodude #10743
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Cool artical:dance:
Thanks for posting that I will definatly have to download the software and play.
Posted: 9 years 2 months ago by michielv #10710
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If you want to build a boat but don't want to commit to the costs of a mould etc. you could try the method as used by Shaggy Designs (, then go to the \"design\" area). Of course you can build the plug any way you want to.

Wow, I wish I'd have a few spare weekends at hand to do this. I've got just about everything (foam, resin, glass, 15+ year of boat reparing experience, a garage to work in) except for time..
Posted: 9 years 2 months ago by AdrianTregoning #10708
AdrianTregoning's Avatar
If anyone has a boat designed on CAD then I'll do a 3D model of it in Inventor. This will give you a couple of interesting bits of information. Maybe a cross sectional profile every 10 or so millimetres and then it will be pretty simple. Files in *.dwg format please. Should be fun to see ;)
Posted: 9 years 2 months ago by Hox #10707
Hox's Avatar
My English ????????

I think its two different ways of taking on the shaping prosess when you talk about a solid block of foam or the, lets say in my case 10 cm thick pieces.
If you use the program to draw sections and the follow them almost presicely you will know what you get (volume and so), but there will also be some problems with differenses in matereal, i mean all gluing sections will be a bit harder than the foam.
AND all, i mean all deifferenses im materal on the plug will make it harder and more time consuming to make (smooth?).
But if you use a solid block you will have to be a better \"freehander\" i guess.
Take the time to make the \"foamshaping\" as good as you can, every time you say \"i`ll fix that with filler or something\" you´r a looser.

But it could be a good idea to do a semi good plug and then make semi good moulds of it.
Just paint the foam and put 2-3 layers of releasefilm on it and in the semi good moulds make your first test kayak, i guess you will change something after testing it, i did.
The thing that by far takes most time is to make the surface ferfectly (smooth?)

And when you want to change an area on the finnished test boat you can use 2 comp sprayfoam to make new shapes (polyuretan foam /swedish).

And i seal my deck and hull when they still are in the moulds with glassfibre and polyester.
You can cut the excess mtrl after laying up your first boat in the moulds when its almost (maybe 1 hour) dry with a rasorblade
The cocpit rim was made on the finished boat by filling the edge with plaster
and then fiber it up and then removing the plaster.

I guess im mutch better speaking English than writing so if you want you can call me.
or +46857029558
Posted: 9 years 2 months ago by Urge #10695
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Hox how do you seal the tow parts together and how did you make the cockpit rim i want to have a go looks alot of fun
Posted: 9 years 2 months ago by cswoodard #10675
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for your foam, you used 10 cm thick blanks that you glued together?
We already have a design set up and foam to make the boat (check the other playak post on this) but were wondering whether a solid block of foam, or laminated pieces are a better option. In your opinion, which method is easier for molding the plug? Wood or foam? Thanks,
Posted: 9 years 2 months ago by Hox #10659
Hox's Avatar
Hogge here (hox)
If you have 1 winter and a good place to mess around in you should be able to do it.
Its a lot of work but its definitly worth it.
Posted: 9 years 2 months ago by Jeroen #10658
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Very interesting article, I agree.

Unfortunately I'm too busy building a website, otherwise I would definitely give this a try :)
Posted: 9 years 3 months ago by ScottBarnes #31035
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You guys see this? It's an awesome article that gives a little insight into the process of boat design. I'd like to hear just how much extra tweaking and adjustments needed to be made in real life after the CAD mock ups were laid out.




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