Sunday, September 26, 2010

Upgrading a classic surfski - converting a double footwell to a single footwell

I know you've thought about modifying a double footwell to a single footwell ski, but cringed at the idea of Dremmel-ing into your three-thousand toy. You've probably thought you needed to be either crazy or have someone give you a free ski to butcher. I'm writing this post to say you need both.

I had been paddling a leaky, glass, 45 lb Fenn Millennium. A friend had a similar model Fenn. His was a carbon ski, but had a mystery leak, and he couldn't quite figure out how to patch it. He had just bought a new Epic V12, so he offered the Mil to me, free of charge. Aside from the leak, the footwells were about 4 1/2 inches too long for my freakishly short legs (despite the our height difference of only an inch).







So with Sharpie, a tape measure, a Dremmel, and a few beers, I started down this path of reconstructive surgery. I was able to use my old Mil as a reference for sizing, as it actually fit me.

I wanted to flange the single part with the existing gunnels and deck. A flat plane exists between the foredeck and under where one's knees go. I was able to use this plane to work from in developing a mold for the part.






I used 2" pink foam insulation in layers for the mold. I used the existing single footwell as a reference, and shaped the foam to match. I also used the foam for the base from which to build from. The base was the plane I was mentioning earlier.






I then took bondo (autobody filler) and gave the foam a hard shell. I also was able to narrow the width of the mold where the heels go, so I could drop the footwell about 3/4 of an inch. I figured that would give me a little more leverage while paddling, without sacrificing too much stability.









After countless coats of autobody filler and reams of sandpaper, I was finally satisfied enough to paint the mold. I used a spray appliance enamel. I then waxed it with 5 coats of mirror wax, and brushed it with film release (a fine spray would have been better). In hindsight, I should have covered the model with glass first, and used epoxy so the mold was really hard and could be used multiple times. Using only bondo made the mold rather fragile. But I was only planning on using it once.....












After a first layer of carbon had been cut, laid onto the mold, and wet-out, a layer of core material was applied.



















After a second layer of carbon was applied and wet-out, the part was then layered with release fabric, breather material, and vacuum bag film. The vacuum bag film was taped to the hard back with double sided tape. A tube from the vacuum was sealed around the tape through a sponge to help keep the bag from clogging the tube. A air compressor was used with a venturi vacuum generator.













The part after the cure.



















After applying 'gentle' pressure to release the part from the mold.....


















....epoxying the part into the boat....



















.....fairing the lip of the flange with autobody filler......













....and three coats of single-part monothane with a disposable spray can. While I was at it, I re-finished the entire boat, sanding with 120 grit then 240 grit paper. The monothane is thick enough so as not to require any finer sanding. Oh, and I found the mystery leak around the rudder post by filling up the hull with water and seeing where the water came out.














Here's the finished single footwell. I had put two layers of carbon-core-carbon near where the foot pedals would attach (with stainless steel screws). The cables were replaced. The ski still needs a single veturi (working on a design) and a toe strap. I'm thinking of a bar made from a cut down paddle shaft. I'd recommend not using a new paddle.















...and here's the finished ski. I used marine detailing tape for the black seam. The ski is currently in transit to Berkeley Marina, where, when not screaming downwind from Fort Baker, it will live on top of my 33', 1962 teak-hulled motor sailor, the 'Kizmuit'. More on THAT in my next post.....

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