Sail Forces...again

[nemo]

Hi,
I need formulas for estimating sail forces in terms of lift and drag, or propulsion and lateral components. I know you'd answer "they cannot be calculated with a formula", but I need a rough estimation, I guess there's something like that on Larsson's book but I still haven't got it.
Thanks

[redcoopers]

This may help:

http://www.redcoopers.net/VPP.htm

-Jon

[8knots]

I picked this book up this weekend at a used bookstore
Aero-Hydronamics of sailing By C.A. Marchaj Tis the revised and expanded edition printed in 1990. This text is the most indepth 731 pages of math and thoery I have yet. I know it has what you need! This fellow also wrote
Sailing theory and practice & Seaworhiness:The forgotten factor
I will pick them up too as I find them
Good luck 8

[nemo]

Thank you redcoopers, interesting site...

[patrik111]

Have a look at
http://www.wb-sails.fi/news/SailPowerCalc/SailPowerCalc.htm

Requires appearent wind and speed though.

[tspeer]

Problem with Marchaj is he has lots of anecdotal evidence to illustrate various principles, but he doesn't present organized, systematic engineering data that you can use in design.

I think the Hazen/IMS/Navy 44 model is the current state of the art, unless you're prepared to do some serious CFD or testing of your own. I've compared the Hazen model from Larsson & Eliasson with the WB Sail-Calc, and I think the Hazen model seems to produce more reasonable results.