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Are loose footed sails more powerful?
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I luv Wight View Drop Down
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    Posted: 17 May 06 at 10:29pm
It's a rule thing for N12s.
N12 rules don't actually measure the foot of the sail - only the black band measurement, so you get a really full sail ( for the offwind stuff ) but it can only go out on the boom so far ( with a stop ), so then you pull fwd on the tack to flatten it. Loose foot sails can cope with this big change in fullness and length better.
The plan is to get as much power as possible downwind, whilst still getting just flat enough for upwind.
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Chew my RS View Drop Down
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Thank you
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Originally posted by Chew my RS

If loose footed sails are easier to rig, cheaper to make, and no slower, why did they use to be tracked?


'Cause it dates back to when all sails were laced to the boom. If you go back far enough part of the load from the sail came through the lacing whih meant the boom didn't need to be as strong. Once people started to understand about sail shape the lacing stopped doing anyting structurally. It certainly wasn't doing much by the 1930s.
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Posts: 1599 		Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 06 at 8:24am

There was a theory that loose-footed are less powerful, because breeze leaks between the sail and boom, whereas on tracked the boom effectively forms part of the sail area. I don't think well-informed opinion believes this anymore.

Also I presume roller-reefing would require tracked. No longer common but it used to be on smallish yachts.

 



Edited by Stefan Lloyd
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Posts: 790 		Post Options Post Options   Quote Chew my RS Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 06 at 8:10am
If loose footed sails are easier to rig, cheaper to make, and no slower, why did they use to be tracked?
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Posts: 1599 		Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 06 at 4:39pm
In classes that allow the choice, quite a few people find loose-footed mains more convenient to rig, but I've never heard it suggested before that they are either more or less powerful.
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Posts: 124 		Post Options Post Options   Quote Bruce Starbuck Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 06 at 3:17pm

Matt, I think what they are referring to might be the extra area you get from the foot round on a loose-footed sail, not anything to do with the depth of the sail at the foot or not being able to ease the outhaul enough.

I've never sailed a boat with a tracked footed main and gone down a reach thinking, "Damn, if only I could ease this outhaul a bit more, then life would be great!"  You can ease off the outhaul as much as you like on either type of main.

Wheras a main with its foot in the track will not be able to extend below the boom, with a loose-footed sail you will get say 30cm of foot round which will sort of fold itself up against the boom when the outhaul is on, but will drop down and set when you ease the outhaul.

So you get a little bit of extra area, but I'd be very sceptical of exactly how useful it is down there below the boom. Still, it's probably worth having, and a loose-footed main is easier to build than one with a soft shelf foot and boltrope, so you might save a couple of quid too.

 

 
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 06 at 2:58pm
I would have thought the power potential of having a loose foot would be dependant on wind strength and boat speed.  In the lighter winds it is much easier for the wind to flow around a flatter sail, and so a full foot would be more of a hinderance.  Though certainly in the upper wind conditions, the wind has the strength to keep flow attached to a fuller sail and thus with the wind being able to travel a greater distance round the the back of the sail, more power developed.

I would then guess that a loose foot sail would certainly help through the range of mid to upper wind conditions but not be as quick in the lower wind ranges. 
With that in mind it could then be said that the loose foot sail will improve speed in a vaster range of conditions than what it would lose, so possibly a good investmant indeed.

Doug

Edited by Doug.H
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Jon Emmett View Drop Down
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Posts: 988 		Post Options Post Options   Quote Jon Emmett Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 06 at 2:57pm
Remember more power does not always equate to more speed due to drag...
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Posts: 1100 		Post Options Post Options   Quote tack'ho Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 06 at 2:28pm
I would have thought it would make the rig a little more powerful as the extra depth gained by the loose foot will continue up the sail for about a 1/3rd of its height.
I might be sailing it, but it's still sh**e!
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