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Old 30-03-2009, 00:24   #1
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Mainsail Creases

Do any sailmakers have any idea what is causing these creases in a brand new mainsail ??
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Old 30-03-2009, 05:17   #2
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I'm neither a sailmaker, nor a qulaified Cat' sailor; but I'd attribute the creses to Sail Trim.

Generally, horizontal creases, in the mainsail mean that the luff should be tighter; vertical creases (what you appear to have) indicate that the luff is too tight, and you probably need to ease the halyard and/or Cunningham.

Alternatively, you may have too much mast bend (more than the mainsail’s luff curve). A sign of too much mast bend is creasing running from the clew toward the middle of the spar.
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Old 30-03-2009, 05:50   #3
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Looks like the sailmaker did not assemble the panels well. Call your sailamker and take them for a ride.
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Old 30-03-2009, 06:51   #4
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The "creases" and excessive bend in the top batten tell me the leach is over tightened. Try easing the vang and mainsheet a bit, tighten the outhaul and ease the traveler to leeward.

FWIW...
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Old 30-03-2009, 22:58   #5
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Thanks for your thoughts. I have tried every thing that you have said, the photo shown is in no wind with the weight of the boom holding the leech. it makes no difference when sailing even with a lot of twist and sheet eased. The creases start to appear when the main is at about a third of the way up and continue down as it reaches full hoist , so halyard tension has nothing to do with it . The sailmaker is blaming the hydronet cloth , but no one has come up with a solution ??
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Old 31-03-2009, 15:21   #6
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Privileged,
If you made the sail and rigging adjustments suggested by others and the creases are still there, then I may be stating the obvious...either the sailocloths is poor or the sailmaker installed the panels incorrectly. I am not familiar with "hydronet cloth". Please let us know what you find out.

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Old 31-03-2009, 15:27   #7
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I agree with that. Either assembly or cost, after looking closer I would tend to agree the material is probably at fault. The sailmaker should build you a new main gratis.

Let us know how it goes.

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Originally Posted by jimking100 View Post
Privileged,
If you made the sail and rigging adjustments suggested by others and the creases are still there, then I may be stating the obvious...either the sailocloths is poor or the sailmaker installed the panels incorrectly. I am not familiar with "hydronet cloth". Please let us know what you find out.

jim
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Old 01-04-2009, 06:42   #8
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Originally Posted by privileged View Post
... The sailmaker is blaming the hydronet (sic Hydra Net) cloth , but no one has come up with a solution ??
Dimension-Polyant's “Hydra Net”, is a standard woven Polyester-Dacron with threads of “Dyneema” (UHMWPE, or Ultra high molecular weight polyethylene) woven through it, in a grid pattern, to give the cloth greater stretch resistance and improved tear strength. Hydra Net is approximately 50% more expensive than ordinary Dacron

http://www.dimension-polyant.com/en/..._Hydra_Net.pdf
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Old 01-04-2009, 10:10   #9
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looks like the weight of the full battens is deforming the main and causing the wrinkles.
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Old 02-04-2009, 08:10   #10
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Vertical creases are the result of unequal load lines through the fabric whether the fabric is lightly or heavily loaded. You can prove this to yourself by laying a hand towel out on a countertop and pulling on opposite edges—creases will appear between the points at which you load the towel. And, the lighter the fabric, the more quickly the creases will appear.

Upon further examination, I notice that while the tell-tales are drooping, indicating little/no wind load, you have quite substantial draft in the sail (take the photo and draw a straight line between the luff and leach ends of one of the battens). That tells me that even with only the weight of the boom hanging on the sail, the leach is, relatively, loaded up and trying to straighten between the boom end and the mast head, pulling the roach inward, creating draft and conincidentally, adding to the creases. The simplest solution may be to simply increase the stiffness of the battens somewhat. I don’t know how costly battens are in your area but it might be worth buying a stiffer replacement for one of the ones you have now to see how that improves matters. You can also increase the stiffness of the existing battens by adding a thin layer of glass fiber to either side.

FWIW...

s/v HyLyte
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Old 02-04-2009, 08:26   #11
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I disagree with svHyLite

I think the problem here may be a combination of too much luff tension combined with too much batten tension.

That sail is trying to tell you something. All you've got to do is listen.
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Old 02-04-2009, 09:00   #12
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Looks like too much tension on the battens!! The draft is full for no to lite winds.

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Old 02-04-2009, 09:29   #13
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I think it's the string of Christmas lights that's causing the problem ;-()

Okay, back to serious: it's not too much batten tension as that would create diagonal creases, not the vertical as in the photo. I agree with the posters that your battens are not stiff enough... or too old. Take one to the shop and compare stiffness. If new ones are much stiffer replace. If the difference isn't that big, buy two stiffer ones and see if the creases disappear between these two. Also, watch batten tension as you could increase tension a bit with stiffer battens without putting more draft into the sail.

It's also not the HydraNet material per se. We have Hydranet without these creases. But.... some sailmakers decrease the weight of the cloth when going to Hydranet (because it's stronger) and that might lead to creases. Some still need to get used to the idea that Hydranet is for bullet proof cruising sails, not racing sails (use laminate or molded for that). In short: cloth too light leads to instability with creases as the result.
Our sails use two different weights of cloth for different panels (can only be done with tri-radial cut!). This saves weight where possible.
I think there's a bit of blame for the sailmaker in this case or inexperience with Hydranet. In his view the Hydranet might be at fault but it really is his error and he's just trying to cover his *ss finding excuses etc. He should not build and sell sails with Hydranet if he can't do it without creases like this.

Also: we replaced our (round) battens with new ones and they were twice as stiff as the 12 year old ones. We had to decrease batten tension with the new battens.

So I think you can correct this with stiffer battens but you should kick the sailmaker a bit too.

cheers,
Nick.
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Old 02-04-2009, 09:55   #14
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Ah, the draft: I think it looks good except the upper two battens. These should have less tension or be shortened or replaced with stiffer. But the rest of the sail looks like every bat-wing I've owned or seen. There's a degree of draft built into the sails at the luff end, more than for more traditional shaped sails and closer to the perfect air foil..
Basically the tell tales on the aft end of the battens should have the same angle with the sail for every batten. This shows if the sail has the right twist. The tell tales at the luff and middle show if you have the right draft or if the sail is stalling. The perfect trim is when 3 conditions are met: draft, twist and angle to the wind.

Also, as materials go high tech, trimming for different conditions becomes more important and that includes batten tension. In very light conditions like in the photo, a little less tension would be better and might decrease the creases somewhat... but it's not the cause for a cruising sail.

HyLight's example with the towel is a good one and shows that these creases can be dealt with by tensioning the cloth between luff and leech more (with the battens). Another good example is the plastic wrap on a dish.

Last detail I see is that there should be more tell-tails closer to the luff.

All this is very well explained in the book "Sail & Rig Tuning" by Ivar Dedekam. I checked it for the creases you have and they aren't listed, confirming that they aren't caused by the standard trims like leachline, halyard, outhaul.

cheers,
Nick.
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Old 02-04-2009, 15:33   #15
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You are generally being led up the garden path here - Joli, etc stating it is a sail cut problem are putting you on the right track though. The creases are almost certainly due to bias distortion in the sail cloth used for a radial cut sail and no matter what sail trimming or playing around with battens you do will eliminate it. This is a completely different issue to creases found in cross cut sails made of dacron and which are generally due to poor sail trim.

To avoid lengthy discussions and argument here I suggest you go to an independant well regarded sailmaker and ask him to describe what bias means with respect to cloths used for radial cut sails - if you are having difficulties with your own sail maker you will have to visit another sail maker in any event. Get his advice as to whether it should be fixed (if it can be) or whether it is no more than cosmetic.

Tri-radial cut sails are normally built using laminates due to bias problems if the likes of dacron is used. Hydra-Net is dacron reinforced with high modulus threads (as GordMay has pointed out) and can, but not always be suitable for radial cut sails - some Hydra-Nets (earlier ones only I think) were fill biased and are not generally suitable. Also, from the photo it appears from the transparancy of the sail that it might be built from quite light weight cloth - if that is so and the cloth is too light for the structure then that may also be part of the bias problem. Given the cost of Hydr-Net that may have come about as a cost saving measure on your own or the sail maker's part.
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