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formula fin

 
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lenthomasphoto



Joined: 23 May 2014
Posts: 19

PostPosted: Thu Jun 19, 2014 4:48 pm    Post subject: formula fin Reply with quote

What is the shortest fin possibility for a formula board?
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zirtaeb



Joined: 03 Jul 2009
Posts: 2366

PostPosted: Thu Jun 19, 2014 7:12 pm    Post subject: Reply with quote

Light sailor, powered up, somewhere around a 52cm.
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rangerider



Joined: 19 Jul 2009
Posts: 153

PostPosted: Sun Jun 29, 2014 8:24 am    Post subject: Reply with quote

Maui Ultra fins sells a carbon delta fin for formula that is about 30cm. I haven't used it but would love to try it as it would be great for the lakes I sail. It is a fascinating concept and more appropriate for formula than anything. I saw a magazine review of their delta fins and the results were good but the carbon formula fin was not tested. As I recall they felt the upwind ability suffered slightly.
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zirtaeb



Joined: 03 Jul 2009
Posts: 2366

PostPosted: Sun Jun 29, 2014 12:05 pm    Post subject: Reply with quote

If you are talking about non planing, not in the footstraps light wind sailing, then anything longer than 25cm is plenty for a good sailor to maintain upwind while having fun on a 5 meter sail.
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beaglebuddy



Joined: 10 Feb 2012
Posts: 685

PostPosted: Sun Jun 29, 2014 2:23 pm    Post subject: Reply with quote

I suppose it depends upon if you want to be planing or not, sail must match the wind to plane and the fin must match the sail. As Zirtaeb says if not intending to plane then it just needs to be big enough to keep from getting pushed downwind.
I can't think of a worse board to be slogging on besides a sinker that would be underwater. That 100 cm wide nose would push a lot of water.
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d0uglass



Joined: 28 May 2004
Posts: 1064
Location: Bonita Springs, Florida

PostPosted: Mon Jun 30, 2014 8:11 am    Post subject: Reply with quote

Minimum fin size for a board is dictated by two things:

1. Is the fin big enough to cancel out the downwind push of the sail and allow the board to move straight forward without side-slipping? This is determined by the surface area of the fin. A short, wide fin can provide as much surface area as a long narrow fin.

2. Is the fin long enough and vertical enough to provide the force needed to keep the board riding level, side-to-side? If the fin is too short or too raked-back, then there is a tendency for the windward rail to sink, which makes you go slow and catch water with your heels and stuff. It's especially important to have a long fin on short wide boards where the footstraps are way out on the edge.

So...

For "normal" shaped formula fins, you generally don't go smaller than the low 60's cm range.

When you need to sail in shallow or weedy water you can use a shorter, fatter fin in the 50s cm range. You'll be able to sail without spinning out, but the board will go slower and will tend to sink under your heels more.

_________________
James' Blog: Windsurfing Equipment Size Calculator
http://jimbodouglass.blogspot.com/2010/11/updated-windsurf-calculator-online.html
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zirtaeb



Joined: 03 Jul 2009
Posts: 2366

PostPosted: Mon Jun 30, 2014 11:48 am    Post subject: Reply with quote

Some of the top Formula racer's of the past few years have been using 56's on their L-12 Formula boards, with varied success against L-12's using 66's.
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