: I have until June to build it and have no limit on the budget. The only
: materials allowed are cardboard, tape, adhesive/glue and sealant/paint. I
: have some real solid construction techniques (last year's boat is still
: fine!) and use lacquer inside and out for waterproofing. I can get
: cardboard in 4ft x 8ft sheets so material is not a problem.

You should be able to plug the corrugations with paint and overlapped tape, so waterproofing for a short race seems to be fairly easy. An eggcrate approach to bracing the inside of the boat was suggested, and if you go for a longer design you should consider this. Laminated strips of corrugated cardboard have impressive strength, but only in one direction. You have to worry about the orientation of the corrugations.

Get some waterproof, or very water resistant glue and look at designs for long slim boats. Besides being a faster shape, the narrow boat will be easier to paddle with hand paddles. If you want to have a really good "fit", make the width of the boat about 2 inches more than the straight line distance from one of your armpits to the other. hae someone measure this with a yardstick. This way you can get low over the edge of the boat and have a free arm movement as you paddle. The reason why you want it 2 inches larger than your body is that you will need to add a lip (or a gunwale) of built up cardboard about 1 inch thick (and 1.5 to 2 inches high) on each side of the boat for stiffness and strength.

My observations of old pizza boxes shows me that corrugated can be curved very nicely, even against "the grain" if you get one side wet and let it stretch out with modest pressure. This might help you fit it around a curved form, and build in some shape. If so, then you might be able to create a smoothly curved hull with fewer seams and gores -- which should have lower resistance and go faster. You might want to try and experiment with this. Heat and steam (from a steam or a heat gun) might allow a more dramatic curvature. It might be a slow process, though. Once the stuff has dried and you lacquer it it should hold those curves forever.

: On last year's
: boat, I tapered the bottom of the bow so that the tip of the bow sits 2
: inches higher that the rest of the bottom of the boat. Did this help, or
: hurt, or have no effect?

With just the information you've given on this, it would be hard to give an accurate answer -- but let's assume that it really didn't make a lot of difference. With the taper you might have decreased the surface area of cardboard which was in contact with water, and correspondingly idereased the water resistance -- but at the same time you reduced the displacement of the boat in that area. That affects balance and might cause the boat to sink a bit lower, increasing drag.

The taper would also affect turning ability, making the boat a bit easier to turn. That would mean more effort to keep the boat on a straight course, which could be wasted effort on a course with long straight sections. This would be more suitable for a slalom course, or one where there were a lot of turns. In such a case a boat that turned easier or faster would have a competitive edge.

Most boat designs are compromises where the different elements of the design, such as: length, width, depth, freeboard ( height aboe water), displacement, rocker, fish-form (widest about 1/3rd of the way from the front and tapering off), swede-form (a sharp, narrow front end to the boat, with the paddler about 2/3rd of the way back), or symetrical -- and so on, are balanced against each other. Making a model helps a lot, but there are computer -based programs that can do the computations for a mathematical 'model' much faster. I've mentioned the Bearboat program a couple of times this week already. This could give you some very specific answers to you questions.

Take a look at:

http://www.marinerkayaks.com/mkhtml/downloads.htm

Also, take some time to go back through the kayak design area on this bbs. You might find some postings which will add to your ideas.

Good luck with this, and please keep us informed of how you are going. A few pictures would be nice

Oh, and get a lot of arm exercise between now and the race -- building up the "motor" is as important as building the boat!

PGJ