Genny luff tension ?

[Bleemus]

The sailmaker will tension the luff tape when attaching it. They use a block and tackle and once tensioned they staple it to hold it in place while they sew.

As a former sailmaker it is easy for a new sailmaker to overtension it. Bring it to the sailmaker and they will remove it and retension it with a bit less tension. Easy fix. I used to do these while people waited in about 20 minutes.

[jrbogie]

Originally Posted by Jd1

Got a new 135 genoa last year. Didn't use it much until recently. Here is a picture:
Going under the assumption that my halyard is about as hard as I dare to crank it, is it reasonable to say that the sail will stretch to take out the wrinkles?
The halyard is really bar tight although it is a rather stretch halyard. Still, tension is tension ...
I had the sail to the sail maker to shorten the strap on the tack a bit assuming I was topped out for sail lift but it seems I have plenty of room left between the mast head and the top of the furling swivel.

The sail was recently exposed to some 25 knot winds and that seems to have possibly reduced the issue a bit but it is hard to say.
I tend to run the sheet to the front of the genoa track in order to prevent twist and spilling the top of the sail - could that be an issue causing the wrinkles or at least increase the issue ?

Do people usually attach the tack to the furler in order to avoid the sail coming away from the sail track between where it leaves the sail track and the furling drum? You can see a slight crease radiating out from where the sail leaves the track. I sure hope that this description makes at least a bit of sense .....

genoa car all the way to the front of the track with a 135??? looking at your sail i see too little luff tension and genoa car waaaaaaaaaay to far forward. there's a term in sailing that is common to flying. tlar. that looks about right. some get it, many don't, but your sail trim looks far from right.

[Cheechako]

Originally Posted by Dockhead

Pay attention to this! Don't scrimp on the halyards. Otherwise the money you've spent on new sails won't do you any good.

What happens is this -- "tension is tension, right" -- NOT! This confuses static tension with dynamic tension. You may get 300kg of static tension on the halyard (say) with the winch, but when you start sailing, the forces imparted by the wind may add a ton to that. If the halyard is stretchy, then the static tension you put on disappears and the shape blows out.

One of the best places you can spend money is on decent halyards. Use racing dyneema. It won't cost you $1k.


Having struggled with stretchy halyards on a previous boat, I knew not to make this mistake when I had my mast out 3 years ago for rerigging, and did all new dyneema halyards. What I did NOT know was that stretchy sheets also cause similar problems. When I had new sails made last year, I made a big mistake by ignoring Uncivilized's advice to use dyneema sheets. It happens that I chafed the sheets last year and had to replace them this year. This time I went with dyneema and -- wow, what a difference! I think I was confusing dynamic and static tension in my mind, when I formed the mistaken idea that stretch in the sheets doesn't matter much. I was wrong!

I doubt the halyard suggestion. We all used Dacron halyards for decades racing and didnt have to live with wrinkled luffs.

[alback]

Hi,
Definitely not sitting right according to your photo. Get the sailmaker on board to help you determine the real problem. If you asked for the extension, it may be the cause, but the sailmaker should know your boat and quickly arrive at the correct solution.

As to lead position, most sails will have a piece of tape/material sewn at the clew that points directly at the mid point of the sail luff. Adjust your jib car such that your jib sheet is colinear when taut with this tape.

Another way to set your car is using your telltales. They will all fly at the same time if your car is set correctly. If top telltales do not fly at similar time to lower telltales, move your car forward, small adjustments at each tack.

Another point, 25 knots is a lot of wind for this sail and may cause overstretch. You could use your furling to reduce the pressure on the sail, and stand the boat more on its feet.

Hope this helps,

[Jd1]

Update from this mornings fact finding trip:
Stretch in just the halyard was about 4"
The sail moves smoothly up and down
The tack strap is 4" long
The sail has about 6" of extra hoist room when the tack strap is not fastened down
Just hanging without the tack strap the sail looks just fine (now)
The most interesting part, with roughly the same tension as originally applied to the halyard just before my recent trip, the halyard now is 3" tighter/shorter. In other words that is the creep/stretch the sail and halyard experienced over about 3 weeks of sailing with a lot of heavy (30 knt apparent) wind exposure.

I had previously mentioned that the problem seemed to be less pronounced after the wind exposure. With that extra 3" of halyard movement I am thinking that the issue might have actually resolved itself. Some test sailing will be in order.

[Jd1]

Originally Posted by Ambler

Your furler manufacturer should have a sketch detailing the sails knockback measurements which details the set back measurements of the head and tack attachment points from the bolt rope, also the two recomended measurements from the end of bolt rope to the head and tack.
Get that from the furler manufacturer and drop your sail and compare what it is to what it should be, then have your sailmaker fix it.
Your sailmaker could even have the dimensions on file for your furler.

I never knew that there were 'setbacks' - I will have to look into that. Thanks!

[Jd1]

Originally Posted by Dockhead

Pay attention to this! Don't scrimp on the halyards. Otherwise the money you've spent on new sails won't do you any good.

What happens is this -- "tension is tension, right" -- NOT! This confuses static tension with dynamic tension. You may get 300kg of static tension on the halyard (say) with the winch, but when you start sailing, the forces imparted by the wind may add a ton to that. If the halyard is stretchy, then the static tension you put on disappears and the shape blows out.

One of the best places you can spend money is on decent halyards. Use racing dyneema. It won't cost you $1k.


Having struggled with stretchy halyards on a previous boat, I knew not to make this mistake when I had my mast out 3 years ago for rerigging, and did all new dyneema halyards. What I did NOT know was that stretchy sheets also cause similar problems. When I had new sails made last year, I made a big mistake by ignoring Uncivilized's advice to use dyneema sheets. It happens that I chafed the sheets last year and had to replace them this year. This time I went with dyneema and -- wow, what a difference! I think I was confusing dynamic and static tension in my mind, when I formed the mistaken idea that stretch in the sheets doesn't matter much. I was wrong!

This is very interesting .... Halyard replacement had been on my mind for a while but I would not have used high tech line without the comments you just made. I have a roll of 3/8 Samson XLS that I used for some other lines and that was going to be used for halyards in the future. I will use that for replacement.

[Jd1]

I just looked up the specs of Sampson XLS and it appears to be a substantial step down from the suggested Sampson MLX. Is XLS usable or is it too much of a compromise ?

[UNCIVILIZED]

Your halyard is "shorter" now because when you released the tension that had been on it, it returned to it's original length. But once it gets loaded up again for a little while, it's going to stretch again, just as before, & likely about the same amount.

3/8" Dacron, be it XLS, or something else, is really too small on a boat that size. And XLS is going to stretch as much or more than almost anything except perhaps Nylon. Plus, you probably have XLS or it's equivalent up there now.

Look up how much a halyard material stretches at X% of it's breaking strength, via the cordage maker's website. And see how much 50' of line stretches when the load on it doubles, due to a wind increase, or your boat falling off of a wave (every 10sec). It's not insignificant in the poorer materials.

Any more, using Dacron for halyards is rather silly, due to it's relatively poor stretch & wear characteristics vs. other cordage types.
It'd be like buying a CQR instead of a Rocna, when purchasing a new anchor.

If I were advocating your buying halyards that cost $5-$10/ft or more, then they'd be unneeded, due to overperformance for the intended application. But Warpspeed or it's equivalent is pretty much the benchmark any more.
You can go one step lower, to a blended Spectra core, though you'll run into more of the issues that you're having now, with Dacron. So I can't see going such a route. Especially if you want good performance out of your new sail that cost you 4-figures.

Not to put him on the spot, but Dockhead has replaced virtually all of his lines in the last year or two, with Dyneema cored ones. Meaning pure Dyneema cores such as in Warpspeed, Maxi-Braid Plus, or in his case, due to location & cordage availability, Marlow racing line cored with SK75 or SK78.
As his Dacron (Polyester ones) weren't up for the task, both in terms of stretch, & longevity. Some of the latter was due to sizing & braiding characteristics. But his new lines should give him much longer service, assuming they're correctly sized. As in a decade or more. Without any of the stretch issues of the previous lines.

Edit: Less stretch in a line greatly contributes to it's lifespan. As with each stretch cycle, the line is wearing against itself internally, & that friction adds up. It's what destroys moderate to highly loaded mooring & dock lines, even when they're not touching anything which can cause abrasion on them.

[Jd1]

Originally Posted by UNCIVILIZED

3/8" Dacron, be it XLS, or something else, is really too small on a boat that size. And XLS is going to stretch as much or more than almost anything except perhaps Nylon. Plus, you probably have XLS or it's equivalent up there now.

Just so I get this right, if I go for some Dyneema (Warpspeed) kind of line you still think that 3/8 is too small even though the load rating on the line doubled or tripled ?

[UNCIVILIZED]

If you go with something Dyneema cored, 3/8" is plenty big enough. Especially as it's breaking strength is 10,000lbs. But if you stick with XLS, go to 11mm or 12mm, as much for stretch resistance, as well as strength.

[Jd1]

Cough wheeze .... Just got some pricing and this is definitively not a 'casual' purchase
3/8 Warpspeed is 3.28/ft
3/8 MLX is 1.98/ft
If I am doing the genoah halyard I might as well do the main sail halyard and I figure I probably need 140 ft for each so say 300 ft to be on the safe side. That is $984 for Warpspeed and $594 for MLX. Not the end of the world as such but certainly something that needs budgeting for.

The obvious question - if I get new halyards, do I get $400 more of enjoyment out of Warpspeed over MLX ? I know it's subjective but a little guidance would be appreciated (keeping in mind I am not racing)

[B-Baysailer]

Defender's has3/8 wrapped on sale for 2.47 ft

[B-Baysailer]

Thats warpspeed

[Jd1]

Originally Posted by B-Baysailer

Defender's has3/8 wrapped on sale for 2.47 ft

Thanks but I am up in Canada and freight makes purchasing from Defender difficult.
The prices I mentioned were Canadian $ and it's close to 25% for conversion. By the time you add freight it's cheaper to buy locally.