i understand that it's about L/D upwind, and L downwind.
i've been told, here and elsewhere, that L/D is better for a unarig than main+jib. can't say i have a firm intuitive grasp as to why though.
given these bits as true, why did both BMW-Oracle and Alinghi have bermudan rigs in the last america's cup? the only rule was 90 ft long to my knowledge. would they have been faster with unarigs?
my guess is that the mast is heavier aloft on a stayed unarig b/c it's longer for the same righting moment. better it seems to put sails on both the aft and fore sides of the mast to maximize the sail area to mast weight ratio.
no intuition here either though, just data from what designers have done in races without rules. participants in "the race" all had bermudans as well, except for team phillips. cat boats are extraordinarily rare. why?
not trying to be sarcastic or difficult here. really am just curious to understand how it all works.
on an unstayed rig it might all be different. the added compression from the forestay calls for a heavier mast. fore boom adds weight. is it enough to offset the benefits? i dunno.
sure would be nice to have a two boat campaign to figure it all out.
ben
--- In harryproa@yahoogroups.com.au, Malcolm Phillips <malcolmdphillips@...> wrote:
> I would not assume that the slot effect is 1+1=3.
> The slot effect is a high lift device, but induced drag is increased far
> more than lift.
> For max speed a high L/D ratio (of sail plus boat structure) is more
> important than high lift.
> Its a cost trade-off. The slot effect gets cheaper lift.