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DelmarEdward
Joined: 05 Aug 2012 Posts: 72
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Posted: Fri Sep 28, 2012 8:42 am Post subject: luff vs boom length |
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All other things being equal, and in lower wind conditions, would you want a longer luff and shorter boom, or shorter luff and longer boom length in a sail for early planing? |
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U2U2U2
Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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adywind
Joined: 08 Jan 2012 Posts: 665
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Posted: Fri Sep 28, 2012 9:17 am Post subject: |
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Good question! I'll be shopping for a big size sail and was also wandering about this. Seems like the trend is shorter luff/ shorter boom this days. Will be interesting to get a sails designer oppinion. |
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U2U2U2
Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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Posted: Fri Sep 28, 2012 9:25 am Post subject: |
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adywind wrote: | Good question! I'll be shopping for a big size sail and was also wandering about this. Seems like the trend is shorter luff/ shorter boom this days. Will be interesting to get a sails designer oppinion. |
only way you could have a shorter luff AND shorter boom is the use of cutouts for the boom placement. _________________ K4 fins
4Boards....May the fours be with you
http://www.k4fins.com/fins.html
http://4boards.co.uk/ |
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konajoe
Joined: 28 Feb 2010 Posts: 517
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Posted: Fri Sep 28, 2012 9:36 am Post subject: |
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I'll go with taller sail, too. The wind is 'up there'. |
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adywind
Joined: 08 Jan 2012 Posts: 665
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Posted: Fri Sep 28, 2012 11:15 am Post subject: |
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I'm with you about " the wind is up there" especially on inland lakes. It seems to me though, that the sail head is designed to release the excess wind / a release valve of a sort/, not to hold it and taller sails are more top end control oriented and not so much low end/early planning. I may be wrong. |
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bred2shred
Joined: 02 May 2000 Posts: 989 Location: Jersey Shore
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Posted: Fri Sep 28, 2012 11:26 am Post subject: Re: luff vs boom length |
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DelmarEdward wrote: | All other things being equal, and in lower wind conditions, would you want a longer luff and shorter boom, or shorter luff and longer boom length in a sail for early planing? |
Early planing is all about AREA. Get a race sail with a longer luff AND a longer boom, install an adjustable outhaul, and learn how to tune it properly. A large 8 batten, 4 cam race sail with an adjustable outhaul will will have enough power to get you planing in sub-10 knot conditions with enough top end to be managable at least into the upper teens.
sm |
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isobars
Joined: 12 Dec 1999 Posts: 20936
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Posted: Fri Sep 28, 2012 12:24 pm Post subject: |
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Unless aerodynamics have changed since I was schooled in windsurfing sail technology, greater low-end planing power comes from longer chord length (longer booms) and shorter luff lengths (sails), for a given area. The same goes for fins and hydrodynamics. |
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jingebritsen
Joined: 21 Aug 2002 Posts: 3371
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DelmarEdward
Joined: 05 Aug 2012 Posts: 72
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Posted: Fri Sep 28, 2012 1:49 pm Post subject: |
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my suspicion was that it would be the shorter aspect sail would give more lift, if only with deeper camber(less outhaul).
I have looked through previous years on the Sailworks site, and boom lengths have gotten shorter.
There were some blurbs on the Maui Sails forum about this topic in connection with North Sails race sails, and it seemed to me the gist of it was that at least those lower aspect race sails weren't well liked.
I guess the reason I'm asking is i've looked at Aerotech sails, and the 2 cam RapidFire in the 11 size has a longer boom length than the VMG or their 6 cam race sail. I e-mailed them and they said at least some of the difference was due to the boom cutout size, but the difference is substantial. I am thinking the Rapid Fire may plane earlier, but not have the range and top end that the race sail has, which i care less about, sailing in a low wind area. What do you think? |
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