Board #3

Board #3, Amaru Des Nudo, laid up Sep 19.  120 x 38, 3.8 cm rocker, 3.5 mm concave, extruded poly core, 3.5 lbs fully rigged.  top: 19 oz tri, bottom: 5oz kevlar + 6 oz E. 4 oz internal stringers.  fully wrapped rails.

Dry-fitting the stringers. The idea is to remove a section of foam, overlay a wet piece of cloth, and then re-insert the foam.  Now you have connected the top and bottom skins with good-quality fiber.

Finishing up the stringers before wrapping the rails and laying up the deck.  I was real nervous the first time I wrapped the rails, but it's really no big deal.  Just work mehodically with the squeegee and stay calm.

Ouch!  This is the result after about 15 minutes into the second session for this board.  Should have seen it coming, though.  The bottom is 5.6 oz kevlar plus 6 oz of E-glass.  Since kevlar has about 1/2 the compression strengh of E-glass, there is really very little protection against compression loads in this critical area.  Board #5 will have uni s-glass running on the bottom, should take care of that problem.

Boards 1-3 used extruded poly cores, the cheapo pink stuff from Home Depot.  The only virtue of this foam is it's light weight, about 1.5 lbs/cu ft.  But using a weak foam has really helped highlight the other engineering issues going on with a kiteboard.  I'm convinced that the standard 5 lbs/cu ft structural foam most builders use is too much weight.  On a 125 x 38 cm board there is a potential weight savings of at least 1/2 lb using a lighter but still quality foam.  Board #5 will use a 3lb pvc foam.

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