Lay it over sails you know the size of? This would give an estimate at least unless the sails are completely different in shape.

There is a way to measure but it is overly complicated, one of the old raceboard boffins will be able to tell you.

Take a closer inspection around the foot, on proto sails it is often written in pen under tack or on the foot panel.

If that fails easiest way other than overlaying is rig to find out mast & boom measurements, then compare to other similar sails of that period.

Luff Length (m) X Boom length (m) X 0.75 will get you as close as you will ever need.

4.64 (mast) *1.94 (Boom) *0.75=6.7m^2

The reason its 0.75 instead of 0.5 is to take into account the roaches. The roach factor could be anywhere from 0.7 to 0.8 but it shdol eb close enough.

JB

Check out maui ultra fins site. I remember seeing it showing you how to calcutate fin area. Should be the same for a sail I think

http://www.mauiultrafins.com/MUF7_english/FAQ.html

Just pin it out flat and break it up into 4 triangles. The one which will encompass the luff curve you can multiply by something like .66 to allow for the curve. It is primary school maths, no calculus or differentiation needed. But it would be much easier to lay it over similiar sails and make an educated guess.

dinsdale said...

Squid Lips said...

Might have to get out the grade 5 maths books and see how to calculate area.

Given the many curves etc I'd reckon you might get out the uni calculus books.

Since sail sizes are rounded off to 0.1m^2 (about 2 A4 sheets of paper) you wouldn't lose much accuracy by breaking the curves into a few triangles