myiW Current Conditions and Forecasts Community Forums Buy and Sell Services
 
Hi guest · myAccount · Log in
 SearchSearch   ProfileProfile   Log in to check your private messagesLog in to check your private messages   RegisterRegister 
Fin sizing

 
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Windsurfing Discussion
View previous topic :: View next topic  
Author Message
rtz



Joined: 31 Oct 2010
Posts: 291
Location: Oklahoma City

PostPosted: Thu Dec 10, 2020 10:40 pm    Post subject: Fin sizing Reply with quote

I can't find it now; it seems there was either a measurement or simple formula for determining fin size or a starting point for a board. Measure from the back of the board up to some point or divide that number or something?

Anyone remember something like that?
Back to top
View user's profile Send private message
swchandler



Joined: 08 Nov 1993
Posts: 10055

PostPosted: Fri Dec 11, 2020 2:58 am    Post subject: Reply with quote

There is a relationship between the width of the board one foot off the tail and fin size. Of course, a lot has to do with the size of the sails you want to use.

In my view, lighter winds favor larger fin sizes. With the right flex at the tip, a larger fin can work to your favor.
Back to top
View user's profile Send private message
joethewindsufa



Joined: 10 Oct 2010
Posts: 1143
Location: Montréal

PostPosted: Fri Dec 11, 2020 6:46 am    Post subject: Reply with quote

you measure the width of the board 12"/30 cm from the tail
this is called the OFO or OneFootOff
and is the MAX length of the fin to put on the board

as discussed, there is SO much more to fins than OFO and length !!
{chord,flex, thickness, etc}
a good board/sail/fin combo is something to remember !!

http://joewindsurfer.blogspot.ca/2012/03/fins.html
Back to top
View user's profile Send private message Visit poster's website
rswabsin



Joined: 14 May 2000
Posts: 431
Location: New Jersey

PostPosted: Fri Dec 11, 2020 9:01 am    Post subject: Reply with quote

Check Windances website under the "tips" tab and they have some nice info on fin sizing vs sail size and sailer weight: https://www.windance.com/Windsurf-fin-info-%26-size-chart-25/

Rob
Back to top
View user's profile Send private message
techno900



Joined: 28 Mar 2001
Posts: 3926

PostPosted: Fri Dec 11, 2020 9:26 am    Post subject: Reply with quote

There are a ton of variables that impact a fin choice. While just considering sailing out and back on flat or choppy water, the most critical is board speed.

If you are slogging or just slow planing, a small fin can be a problem because there isn't enough lateral resistance to keep the board from sliding sideways. A big fin at speed can be a problem because there will be too much lift and the board can flip as the fin tries to fly to the surface. This is where board width come in. A wide board is less likely to flip with a big fin while a narrow board is more likely to flip with a large fin.

And as mentioned, body weight is important. Take the same board, same sail and same speed. Sailor A at 150 lbs. needs a fin 30cm in length, while Sailor B at 200 lbs. need a fin 35-40cm in length. The extra weight helps balance the forces trying to flip the board.
Back to top
View user's profile Send private message
manuel



Joined: 08 Oct 2007
Posts: 1114

PostPosted: Fri Dec 11, 2020 2:56 pm    Post subject: Reply with quote

Youll need to account for volume too.
I'm using a 56cm wide board with a 19, and 54.5cm with... 23 and 60.5cm with?... 21 !!!
So it depends Very Happy

_________________
*NEW* - Manu's Windsurfing Blog, The STORE!
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Windsurfing Discussion All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum

myiW | Weather | Community | Membership | Support | Log in
like us on facebook
© Copyright 1999-2007 WeatherFlow, Inc Contact Us Ad Marketplace

Powered by phpBB © 2001, 2005 phpBB Group