[Alberg30] Sail area

[mmeinhold at toadmail.com]

You can find the area of any triangle with Heron's Formula :
 let a, b and c be the lengths of the three sides.
 find the half-perimeter s = 1/2(a+b+c)
 then the area A = sqrt( s*(s-a)*(s-b)*(s-c) )

Mike
Mike Meinhold (soon to be #272)


Quoting Dave Terrell <DTERRELL at message.nmc.edu>:

> It is my understanding that the measurements are for the distance from
> the stem (10.5) to the mast and the height of the mast(36). That will
> give you 189 sq ft. I do not know that real jibs are right angle
> triangles. I believe that if you want a 150% genoa, you just multiply
> the 189 by 1.5. The real decision you have to make is where you want the
> clew on the genoa. if you chose a high cut clue, you will still get 150%
> of the jib area, but the sail will not be a right triangle. I would
> guess that ordinarily genoas do not have right triangles - mine does
> not. I think a next thing is to discuss with your sail maker whether
> what your goals with the new genoa are. If you want to keep the sail off
> the deck to improve visibility, a higher clew would be in order. If you
> race, they other issues become very important. I think your sail maker
> should be able to give good advice. If not, he/she would become suspect
> in my mind. Sorry to take a few days to get back to you - I am not in
> the office every day in the summer.That is one of the nice things about
> college teaching. There really is time for sailing.
> 
> >>> schuylki at vanent.vanebros.com 07/15/03 06:00PM >>>
> 
> Thanks for the reply Dave; I'm encouraged my calculations for the main
> are
> in line with your figures.
> 
> About the jib, though-do you have the foot and luff measurements
> readily
> available? There are max. dimensions for the jib listed in the
> handbook-those are the figures I used. I don't remember them being
> there
> when I had a jib made many years ago, but there it is
> 
> Also, I don't think luff X foot/2=sail area will work for genoas. I
> think
> that formula requires a right angle, and there aren't any on Genoas.
> Gotta
> use all that tangent and sin business. Or, do what the mathematically
> challanged do; lay the sail out on the grass, make a right angle with
> a
> tape measure down the middle of the sail, and add the two areas
> together.
> At least, I think that will work...
> 
> One step at a time
> Thanks again
> Michael
> #220
> 
> 
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