Ah, somebody else that got hooked into the Watertribe Challenge concept. I was turned onto it last year by John over at CLC. I was buying a Chessie 16Lt kit for my wife's first boat and saw proa pieces laying all over the shop. John proceeded to explain what it was and why he was building it. I subsequently went to the site and have been addicted ever since.

In persuing my addiction, a like-minded sailing buddy and myself have (more or less) decided that our chosen route is a full-blown tri. Our thinking goes like this...

Neither one of us has the desire or dedication to paddle the full distance, especially at the pace required to finish within the alloted time. We are both sailors first, paddlers second.

We started out thinking about a planing dingy like his 505. This was killed when we decided that the centerboard draft and near complete inability to paddle into one or two of the required checkpoints was impractical. Some paddling seems mandatory on the original Challenge route due to lots of 6" water and narrow routes up channels against prevailing winds.

So, we went to multihulls. We both learned to sail on a Hobie 14 Turbo and were immediately drawn to, for example, a stock Hobie Miracle 20. This turned out to be too expensive for our tastes and we couldn't find a way to beg, borrow, or steal one.

"Go with what you know." Now we're going to build what we need. The concept is for a max length (near 24') tri. The main hull is to be an S&G double with minimal alterations to accomodate the tri rig and sufficient volume in the bow to avoid submarine imitations. The amas (outer hulls) will be purpose built, near full length, and with enough volume (twice displacement is the general rule) to prevent burrying when flying the main hull.

Displacement vs. planing hull designs becomes a very complex, and somewhat moot, discussion when the fineness ratio of the hull approaches 20, typical for a racing tri. In simple terms, if you make it skinny enough, it won't really "plane" but the bow wave doesn't trap the hull in the typical manner either. This helps allow the main hull to remain a "normal" kayak when not hooked up to the full tri rig.

I chose a tweaked version of Shearwater's Baidarka Double for the main hull. Eric lengthened the hull to 23'-8" and brought the max beam in to 24" (fineness ratio here). The bow volume, cockpit placement, and ease of modification all worked out well for me. The long waterline length vs overall length is a bonus as well.

All gear required to actually sail the thing will be mounted on the amas. This means she'll have twin unstayed masts dead abeam of each other. The appendages (rudders and leeboards/daggerboards/centerboards) will be out there as well. Control lines (or other means) for the appendages will be a large hurdle to overcome.

For masts and sails we have looked most closely at large windsurfer-style rigs. They allow easy stepping, are typically unstayed, and have very efficient shapes (elliptical). In addition, the extreme taper usually found in the masts allows the tip to spill off well in gusts without the addition of extra control lines for vangs, etc. As a bonus, large older rigs are widely available for reasonble money.

The biggest challenge I forsee will be in the akas (crossbeams). They will be under terrific loads (I've calculated some numers that terrify me!) and need to present minimal frontal area to reduce windage and water resistance when punching through waves. In addition, a fair deal of curvature should be built in to get them above the water for the same reason. So far I'm figuring on 2" thick by 10" wide (fore/aft) akas laminated (hollow?) from western red cedar then covered by 2-3 layers of unidirectional carbon and one layer of kevlar cloth.

With a bit of work we should be able to keep the all-up weight under 400# and still be able to paddle short distances (1-2 miles) without killing ourselves. That, and I'll have a killer fast double for touring with my wife.

Wow, seems that I needed to get some ideas down in writing. Anybody out there with some great ideas to help things along?

Porter