Martin Baxter wrote:
What is the largest triangle (area) that can be fitted into an area
bounded by the boom, mast (between gooseneck and backstay crane),
backstay crane and backstay?


Clearly, the largest sail area can be achieved by completely
filling in that triangle... or by thinking "outside the box"
and ignoring the artificial limit imposed by the backstay.
Some boats have sails that overlap the backstay, other boats
don't have a backstay at all.



This is basically the problem that is causing such a kafuffle in a few
other threads here.


No kafuffle, just Bobsprit showing his ignorance.



Now hear is the rub: If we lower the headboard by a foot and increase
the curvature of the roach to meet the headboard at the new lower
position we REDUCE the area of the main. The roach, expressed as a
percentage of the area of the main increases. This happens for two
reasons: 1) The leech is now at a position further forward of the old
on, so the distance from the point of maximum roach to the line
connecting the clew and head is a bit larger. 2) The area of the
triangle defined by luff, foot, and line connecting clew to head is now
smaller. Consequently the roach percentage rises.


Yep. One of the consequences of being able to make sails
with higher roach than before is that more classes are
defining a mid-girth measurement for all sails.


BUT, the overall area of the sail is LESS!


Did you confirm this with a licensed rocket surgeon?


Now why would you not want a sail that hoists to the black band?


A DUCK!!

DSK