Sunday 30 March 2008

Skin on Frame




I've been playing with ideas for Skin on Frame kayaks for a while. They look fun and quick to build, light, and offering options for turning into folding kayaks. So I had a go. This one was in fact not quick to build at all - which is mostly the fault of the rubbish wood which is easily available in the UK! (Or, to put it another way, I should have spent the time to source something better!)

I wanted something that still looked an behaved like a Sea Kayak, but was as short as I could reasonably make it. I ended up at just over 4 m / 13.5 ft, with a 60cm / 24" beam.

I used the Tom Yost ply frames technique (www.yostwerks.com - thanks Tom), and DelftShip to design the original shape. The ply forms take a little while to cut out, but then, if you have decent wood which will bend without breaking, assembly is super-fast. I was making this one as a trial, since the wood was bad and I wasn't certain about the design, so I only tied it all together - no glue, pegs, screws or anything. It was plenty strong enough.

For the first trial (on the open Irish Sea I should add) I covered it in cling film (saran wrap). Despite 6 layers applied tightly it started to leak immediately (not a suprise), but after a few minutes was leaking faster and faster as the film stopped clinging! Still, it did the job before a hurried return to the beach - I knew that it basically worked but some modifications were needed, to improve the manoeuverability. Extra stringers were added between keel and chine, to remove the previous deep scallop whichg develops on a wide hull like this and to give a slightly rounded bottom. The bottom of the stem was also rounded off.

A second trial the next day, covered in garden centre polythene, was much better. No seams so no leaking, a smoother surface meaning it was faster and just felt better, and much more manoeuverable. Pretty much what I was looking for. Even more manoeuverability wouldn't go amiss, but it is only 4.16m / 13.6ft long, so I need to be careful to keep some tracking still, it would be all too easy to lose that completely.

What next? Well I think the experiment has worked, so I'll rebuild it with nice wood, and finish it off properly.

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