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Calculating appropriate board volume
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JPonHudson



Joined: 10 Apr 2013
Posts: 20

PostPosted: Sun Sep 24, 2017 11:08 am    Post subject: Calculating appropriate board volume Reply with quote

I read somewhere that the formula for a boar volume is...

Sailor's weight + 20-30= Board volume.

I also read somewhere that wider boards have the effect of having 15L more than narrower ones. I am assuming that this formula apply to powering up and planning.

Here is a question....if I want to get a board that would have a minimum volume that would allow me to slog upwind if the wind drops, what volume should it have. Is there a formula for that?

I looked at the http://www.riggeek.com/gear-calculator/for-windsurfers but the calculator does not take into account the width of the board. Any thoughts?
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grantmac017



Joined: 04 Aug 2016
Posts: 946

PostPosted: Sun Sep 24, 2017 11:46 am    Post subject: Reply with quote

You can slog any board that you can uphaul, which isn't really affected by width to much extent.
You can get windward on a board that sits mostly under water but uphaul gets very difficult.
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isobars



Joined: 12 Dec 1999
Posts: 20935

PostPosted: Sun Sep 24, 2017 11:57 am    Post subject: Reply with quote

JPonHudson wrote:
Here is a question....if I want to get a board that would have a minimum volume that would allow me to slog upwind if the wind drops, what volume should it have. Is there a formula for that??

Slogging upwind without a daggerboard is an advanced skill, with difficulty increasing with reduced volume. Why complicate the learning process artificially? Buy some instructional videos, use them, then if necessary fly somewhere to get some lessons; it'll be the best $100 or $1000 you ever spent.
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kmf



Joined: 02 Apr 2001
Posts: 503

PostPosted: Sun Sep 24, 2017 12:22 pm    Post subject: Reply with quote

I plugged my stats into the site that you mentioned, I am a advanced gorge sailor, 156 lbs and choose wave sailing. Interestingly, the calculation showed that I should own 79l, an 89 ltr, and a 101 ltr boards to cover a wind range from 15 to 30 knots.

After many years of trial and error, I now own an 80ltr Open Ocean bump and jump board, an 88ltr FSW and a 102 fsw. to cover that range. So I would say as far as volume is concerned the calculator works for me.

The devil is in the details of course, width, rocker, length and intended use all play into the mix....so although my volumes are what the calculator says, it doesn't mention width.


width determines planing ability, volume determines slogging ability. Rocker is yet another factor.

KMF
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joethewindsufa



Joined: 10 Oct 2010
Posts: 1190
Location: Montréal

PostPosted: Sun Sep 24, 2017 1:34 pm    Post subject: Reply with quote

i ride longboards, wide freeride and older narrow short boards
do NOT like schlogging on wide freerides > 90 cm wide
for me narrow boards schlogg better
like longboards, which glide in very light winds
width is supposed to aid in early planing and NOT schlogging ...
as suggested - volume is flotation to get you out of the water and width helps
but not in schlogging

when i started short boarding, I was about 100 kilos.
my first shortboard was 160 liters and 80 cm wide
qwertjj is about 90 kilos and has issues with a similar board
so, this is kilos +60 - for winds under 20 knots
started on that board with a 7 meter sail
went to an 8.5 and even tried a 10-oh ...
it was ideal with 8.x sails ...
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techno900



Joined: 28 Mar 2001
Posts: 4161

PostPosted: Sun Sep 24, 2017 3:16 pm    Post subject: Reply with quote

The calculator seems reasonable, but as has been mentioned, width has little to do with slogging upwind (other than a little more stability). Width won't help you point higher, just plane sooner when you get enough speed.

I have raced a formula board several times in slogging wind. 100cm wide doesn't help pointing, even with a 70cm fin.
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westender



Joined: 02 Aug 2007
Posts: 1288
Location: Portland / Gorge

PostPosted: Sun Sep 24, 2017 6:25 pm    Post subject: Reply with quote

The calculator seems ok but without a daggerboard it seems unlikely you'd ever get upwind.
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NOVAAN



Joined: 28 Sep 1994
Posts: 1544

PostPosted: Sun Sep 24, 2017 6:45 pm    Post subject: Reply with quote

Longer boards with more rail in the water will slog up wind better than a short wide board with the same volume. Volume is how much float a board has. A 115 board, short or long has 115 liters of float. Along narrow board will have more stability front to back than a wide board. The wide board has more stability side to side. I think that longer boards that plane are better for a beginner that needs to slog out to the wind line or up wind. I have some of the new "stubbie" boards and really like them. They do take skills in order to gain the benefits of these shapes. They do not slog well. Would not recommend them for a new or advancing sailor. A traditional free ride would be the way to go. They do everything pretty darn good. Tabou Rocket or JP excite ride are just a few that are proven designs...
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Mon Sep 25, 2017 3:19 pm    Post subject: Reply with quote

The volume chart by Jim Douglas.. I put myself as a intermediate, results were 93 and 108. Changing wind had no effect.

Then went to expert , result was 81 91 106, much much closer to what I feel to be correct.

There are a zillion factors that aren't considered, kinda neat anyway .

_________________
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4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
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LeeD



Joined: 12 Jun 2008
Posts: 1175

PostPosted: Sun Oct 01, 2017 1:23 pm    Post subject: Reply with quote

158 lbs. Minimum volume for stable slogging around 92 liters with 6 meter sail. Easy uphauling in 3 mph breeze an d ws in 10 mph. Slogging is easiest on close reach and slightly higher, harder going broad or lower.
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