Whats the point of a padded luff?

[dedwards]

I'm currently looking at new furling genoas and have read that adding a padded luff makes the sail work better when its partially furled.

But then I thought to myself - the whole point of furling in a bit is to reduce the effect of the sail so isnt that all a bit counter-intuitive? I mean. If you are partially furled and want a bit more power then rather than spending £100 on a padded luff why not just unfurl a bit more?

Or am I missing something?

 

[weaver_fish]

I think the foam ensures that the sail has a better shape to it when it is partially furled.

 

[john_morris_uk]

What you are missing is that the sail tends to become very baggy and inefficient when its reefed and you are sailing to windward in heavy winds. There's good power and there's bad 'heeling' power in sail shape terms. You usually want the most efficient sailshape when sailing to windward, and the foam luff helps with just that. If the thing is too baggy, you can't point as well and you get more heeling moment.

There comes a point when even the best reefing gear with foam luff etc are inefficient and its best to set a proper storm jib on another (removeable) forestay.

 

[VicS]

It varies and it depends on the sail I guess but the fullness that is built into a sail, to give it the correct aerofoil section leads to what can only described as "bagginess" when it is partially rolled. The result is that not only do you have a badly shaped sail but you have it in a situation, ie high winds, when you really want a flatter sail.

A padded luff is a way of counteracting this. The padding is shaped so that it takes the fullness out of the sail as it is rolled.

 

[dedwards]

So what you are saying is that with an inefficient sail shape the wind that isnt used to drive you forward isnt simply lost but instead heels you over more. So if you unfurl an inefficient sail to counteract the loss in driving force it is possible to make that up but you will get a much larger heeling force than if you were using a smaller, more efficient sail. Is that right?

(Edited to improve wording)

 

[michael_w]

Talk to your sailmaker about using a rope padded luff.

The extra rope which is contained in a narrow pocket just aft of the luff rope. As the sail furls it takes out the slack cloth. The leach and foot furl furl quicker than the bunt of the sail. Therefore, without some sort of corrective action your sail turns into a sack.

The advantage rope has over foam is it doesn't compress as much.

 

[KenMcCulloch]

[ QUOTE ]
So if you unfurl an inefficient sail to counteract the loss in driving force it is possible to make that up but you will get a much larger heeling force than if you were using a smaller, more efficient sail. Is that right?
(Edited to improve wording)

[/ QUOTE ]
More or less, yes. By flattening the sail you reduce the amount of 'lift' but you also change the 'lift to drag ratio' so that the direction of force of the sail is a little more forwards and therefore the heeling component is less for a given force.

If you think about what happens when you reef a mainsail that will help you understand what's happening. Taking a slab of sail out of the foot of my mainsail has three effects: it reduces the area (less important than you might think); it flattens the sail (more important than you might think, for reasons given above), and; it lowers the centre of effort of the rig which is very important in relation to bringing the boat more upright.

Imagine that instead of rolling your headsail you had a set of 'reefing points in the foot and the leech, parallell to the forestay (and some means of tensioning towards the head and tack). By tensioning these you would reduce the area and flatten the sail, the foam luff does the same. You will also see some furling genoas with cut away sections in the head and tack areas of the luff, so that when you roll it up the first couple of turns just flatten the sail before starting to reduce the area.

 

[Spyro]

The furlex roller reefing sytems have some sort of mechanism that give what they call a couple of free turns. I think what happens is that the body of the sail starts to furl before the foot does this taking away some of the slack in the belly of the sail.

 

[KenMcCulloch]

[ QUOTE ]
The furlex roller reefing sytems have some sort of mechanism that give what they call a couple of free turns. I think what happens is that the body of the sail starts to furl before the foot does this taking away some of the slack in the belly of the sail.

[/ QUOTE ]Yes that's what I was describing.

 

[dickh]

My previous boat, a Jaguar 27 had a padded foam luff which took the fulness out of the sail when reefed. On a new sail I would always specify it - I think it's well worth the extra cost. Mine was a very firm foam which did not seem to get compressed at all when reefed. My current boat doesn't have a foam luff and when reefed is very baggy.
You should also consider NOT having a sacrificial UV strips as this will also help with reefing(less thickness at the foot & leech) but you would need a pull up anti-UV sleeve which you fit when leaving the boat. Not so handy but will make the sail set better when reefed.

 

[oldestgit]

Hi Spyro:

Which Furlex is that then?

I have a furlex B MK2 and am considering changing it this winter to a 200S or possibly an E, but every one I have seen has the drum solidly fixed to the foil which is uniform in section and they both rotate simultaneously in a fixed circle.

Peter

 

[KenMcCulloch]

[ QUOTE ]
Hi Spyro:

Which Furlex is that then?

I have a furlex B MK2 and am considering changing it this winter to a 200S or possibly an E, but every one I have seen has the drum solidly fixed to the foil which is uniform in section and they both rotate simultaneously in a fixed circle.

Peter

[/ QUOTE ]
Hi Peter
The tack of the sail is attached to a ring above the fuling line drum and the 'free turn' rolls the middle of the sail without rolling the foot or the leech at all. You can read the Furlex manuals here:
http://www.spars.co.uk/hints.htm

 

[oldestgit]

Thanks Ken:

When I read Spiro’s post I incorrectlyassumed there was a mid section such as geared foil that gave the couple of turns he refers to, I maybe read it too literally and didn’t relate it to the turn or part turn that the tack ring gives. On re reading his post I am sure you are right and that is what he is referring to.

Many thanks…………. Peter

 

[kds]

The foam really does the business - if you have a good sailmaker.
I am very pleased with the Genoa I had made from Arun sails in Bosham. 3 seasons now and it still reefs and sets well enough to win races.
Ken

 

[Spyro]

Thanks for replying I haven't been back at this post for a while.