Umm... your windward board snapped off? The one out of the water? My head tells me something like this could happen to the leeward board... but the windward board? the bending windward itself makes sense because that is the direction of lift generated by the foil.



Using bending calculations and making some assumptions about uniform loading, you could SWAG the amount of force necessary. You'd need to know the materials used in construction and the cross sectional dimensions of the foil. If you know any structural engineers, they would probably calc it out for giggles.



Before you go making bulletproof daggar boards, conider the ramifications of making something that broke, unbreakable. Next time you may end up with a half sunk cat because the daggar board trunk got opened up instead of the daggar board valliantly sacrificing itself to the sea.



... my $.02







Paul Scott Bartelt 2001 NACRA 6.0 NA #546