Has my luff rope shrunk?

[Ruffles]

Someone posted on another forum about about a main sail with a shrunk luff rope. The suggestion is that the rope is carrying all the tension of the halyard so that the sail will not flatten and you cannot get the draught to move forward.

I've thought for a while that our main looks baggy. Though the cloth is in good condition it always seems too 'deep' if you see what I mean. And the luff itself sags between the sliders no matter how hard I pull on the halyard.

So can I adjust the luff rope myself? How and where is it attached to the sail? I don't mind getting a sail maker to do it but it is a lot of hassle taking it off the boom, delivering it etc.

 

[Scarboroughsloop]

Maybe ask Lucas or Flew Sails for advise. It may just be that the sail is a bit tired and needs to be re-cut or replaced.

 

[Gin]

[ QUOTE ]
And the luff itself sags between the sliders no matter how hard I pull on the halyard.


[/ QUOTE ]

never heard of a luff rope shrinking, especially as they are synthetic but the quote above indicates, I reckon, that your mainsail luff may be too long for the mast and although the halyard is up tight that's probably because the halyard shackle is jammed into the masthead sheave.

If you have a Cunningham then heaving that down as tight as possible before hoisting the main will then give you enough 'shortening' to see if that supposition is correct.

Alternatively, without a Cunningham, try progressive small amounts of downhaul on the first reef tack cringle and see what you think when you reapply tension to the main halyard

 

[Ruffles]

I don't think I'm running out of halyard. I replaced it last year and checked this.
Might try a cunningham though. Haven't tried one for years. It will certainly prove the issue.
I guess it's not so much that the rope shrinks so much as the sail stretching more than the rope.

How much draught is usual in a mainsail? And how much should you be able to flatten it to?

 

[Ruffles]

[ QUOTE ]
Maybe ask Lucas or Flew Sails for advise. It may just be that the sail is a bit tired and needs to be re-cut or replaced.

[/ QUOTE ]
It's a pain though since I'm only down there at weekends...
Might ring them for advice.

 

[lw395]

Luff ropes often shrink. Some sailmakers provide for this and make them easy to sort, others you tend to end up getting the reinforcement near the tack changed. Not expensive and worth doing. I second the recommendation of Flew Sails, but you might find a loft near home to do it. The Noble insurance website has a good facility to find your nearest loft or repairer.
Of course you may find that a decent cunningham tackle will sort it?

 

[Ruffles]

I keep the boat at Wicormarine where Flew sails are based. It's just such a hassle taking the sail round when they're open. I assume the ends of the rope are hand stitched in anyway? So I guess it's just a case of how much rope is available and how much it needs to be slackened. I take it if you over slacken it you can damage the cloth by stretching.

Has anyone got a copy of the book "Sailmaker's Apprentice" by Emiliano Marino? From the excerpt it seems to cover this topic.

 

[Gin]

[ QUOTE ]
How much draught is usual in a mainsail? And how much should you be able to flatten it to

[/ QUOTE ]

You really need one more expert than I but if you picture the shape of a modern aeroplane wing held vertically, then you would expect the deepest part of a similarly filled sail to be no more than about the first 25% of the chord of that wing when the halyard's tensioned, (outhaul too), at about 1/3rd luff height. If your mainsail has camber lines this is relatively easy to assess but if not probably the best way is to lay on your back on the coachroof, hard on the wind and view up the sail.

Slackening the halyard/ outhaul but still with a tension on the luff should not result in that 'belly' moving aft more than say 40%.

Anything over that and the sail is stretched beyond a controllable amount and needs replacing, a symptom of that condition would be a lot of weather helm, probably a flapping leech which can't be stopped from doing so, and a need to reef earlier than desired as so much power has moved aft making the boat gripe up to windward all the time

 

[Ruffles]

25% is probable what we get. But looking at other boats they seem to have less than that when sailing to windward. Very hard to tell from a distance though. We certainly get some weather helm. I guess if the rope has stretched the depth will increase in the gusts just when you don't need it.

I started sailing in sigmas. They always had wire luffs. I've never really got used to mainsails with sliders and the way they show the slack.

 

[KeithH]

I had a main luff rope shrink. It caused the main to be a bit baggy at the bottom, as the sail was pulled up the luff groove in the mast. Eventually, the excess sail cloth caught at the gate, causing a small tear in the sail cloth next to the luff rope.

It was sorted out by Arun sails, at Bosham (excellent firm , thoroughly recommended.) They undid the stitching at the foot end, and pulled the sail tight on the rope. Then restitched the rope in the right place. Done in 5 minutes.

Apparently, it is not uncommon, but the sail was fairly new. Rope shrinks more than sail cloth.

 

[smeaks]

this is exactly what happened to mine. I could not power up wind because of the sag. The sail maker unstitched it and added 6" then stitched it all in. This season it is much better.

He says it happens alot.

worth the effort to get it fixed and surprisingly cheap.

 

[smeaks]

the sail is sown around the rope thats why the sag appears along the length of the sail between the slides.

 

[William_H]

I would second the suggestion that you try a cunningham. Or even put a reef in. Both of these will quickly show if the luff rope has shrunk. I suspect not.

When a sail gets old it does tend to have too much camber. OK in light winds difficult when the wind comes up. Fixes are outhaul tension. halyard tension (cunningham) mast bend and sheet /vang tension.
If you can't get the camber (belly) out then ypou need a new sail.
Or put a good reef in that will/may remove the camber and the weather helm problems. olewill

 

[Lakesailor]

I don't understand why people are saying it won't have shrunk when others are saying the sailmakers tell them it's a common occurance. I've had it on a dinghy and my Foxcub.
In this piccy of the heron you can see the puckered luff sleeve of the sail over the tight (take my word for it) bolt rope. I freed off the ends, the foot was shrunk as well, and released it which made for much better set.

 

[smeaks]

will,
the reef does not help or the cunningham bescause the problem as demonstrated by Lakesailor is along the length of the luff, in my case a reef shortened the sail but still left the problem in the remainder of the sail. The bag appears along the length between the sliders, so a cunningham will just tension the luff... not the sail which remains bagged on the tensioned rope.

 

[dulcibella]

It is certainly common and I'd advise geting a good sailmaker's opinion on whether replacement will be effective or whether you really need a new main. Lucas will give you and honest and expert assessment - if the news is not good they also make excellent sails for sensible money.