My new light wind board is read to test. First the basic specs:
length: 170 cm
width: 50 cm
rocker: 1.5 inches continous
concave: ? can't remember the number but its flat down the center from the outside of the left foot to the right foot and starts around 3 inches from the rails.
Fins: heel side, center and toe side options
Stance: three widths set off center with a second row more off center.
Rails: square and 3/16 inch continous cast urethane plastic from smoothon. Smooth-Cast® 385 Mineral Filled Liquid Plastic.
Outline: Asymmetrical twin with a more rounded toe then heel and strait rails without side cut radius.
The table surface is 1/8 fiber board waxed with mold release wax. I cut the rocker out line into the 2 by 4 and built the table 4 foot wide and 8 foot long. I placed full width supports allong the underside of the table surface. This allowed me to place a concave stick allong the center. To set the concave I traced the rocker on a 1 inch stick set level with the rocker at both sides of the foot width. Cut it out and tacked it down in the center of the table. This set the center of the board flat under the feet. If I screwed the top down on that the concave would extend past the rails. I wanted the concave only at the center with no concave at the edges. Not wanting to build a press I decided to screw the fiber board down over the concave stick with countersunk screws and cover the heads with packing tape. This worked ok but I think if I do it again I'll sink them lower and fair them in with bondo.
For the rails I created an outline template and routed out a 3/16th inch depth chanel from the underside of the 1/4 inch divinicel H80. The Smooth-Cast® 385 Mineral Filled Liquid Plastic mixed up nice and smooth but set up fairly fast. Next time I'll mix smaller batches. It mixes in a 5 to 1 ratio by mass. Used monoject 2oz cathater tip syringes to inject the plastic into the chanel. Great to have around for building and as part of a good first aid kit. I also cut out full depth 1 inch holes for the fin placements and did them in plastic also. After that set I fliped the core over and sanded down to the rail from the top side.
I used kind of a modified brokite like 6 section idea. I made 5 cuts with thicker cuts in the center and thiner outside. If you think placing the board on a moving table saw looked scary you should try it with a circular saw with the guard taped out of the way. I didn't cut all the way and left the rail in place as I'm just to lazey to make a nice jig.
Layup is 5oz cabon with 11oz carbon in the center with 11oz stringers with a 5oz carbon deck. I used the resin research 2000ce resin with 2100S hardener. Nice slow cure and low viscosity. I'm in love with this epoxy resin.
I have the rails trimmed square and sharp. If I don't like the ride I can round a nice bull nose on later.