Mainsail Creases

[MidLandOne]

Originally Posted by MidLandOne

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.

Should, of course, read - "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 THAT will NOT eliminate it."

[Bash]

bias distortion can only be caused by a load on the sails. That load has to be coming from somewhere. Given the description of the conditions/situation when the photo was shot, it either has to be from luff tension or batten tension.

This is not, by the way, an unusual problem for a woven tri-radial, especially if it's built to stretch properly.

Talk to the sailmaker, he'll help you sort this out.

[s/v Jedi]

I agree with MidlandOne: talk to another sailmaker too....

ciao!
Nick.

[privileged]

Thank you all for the imput. A few answers so far, the sail cloth is definitely not on the light side in fact it was one weight heavier than the recomended cloth and ended up fifteen kgs heavier than its predessor. The battens are new, The sail shapes up very well when sailing and does not look too full in the head, especially as the wind increases.I have had someone up the rig while sailing to do batten adjustments and the sailmaker was on board, It did appear to make a very slight decrease in the creases. I now wait for his next thoughts this week end. Thanks

[s/v Jedi]

Yes I was thinking the head might open up somewhat when sailing. Also, we have a hydraulic boom vang which will keep the boom up in the situation where you took the photo so the sail doesn't have the weight of the boom which will make the head look different. I think the creases might go away when you lift the boom or sail with more wind.

I still wonder how the leech will behave in higher winds, like 25 knots true. If it opens up too much even after increasing luff tension, you know you can have stiffer battens. A trick often done in that case is to make the back-end stiffer by taping a piece of batten onto it (like the aft 2/3 of the batten). This is like simulating a tapered batten.

But overall, I think is shape is good, it looks a lot like mine (from Elvstrom-Sobstad). Also, if you had laminate before you will love this as we don't have a single spot of mildew on it after 4 years. The laminates we had before looked black like carbon sails because of the mildew between the layers....

cheers,
Nick.

[Tempest245]

Is that aft line...a topping lift? it looks pretty taut to me. I have no other opinions regarding the sail construction.

[Sail Warehouse]

I think MidlandOne is probably correct at least in theory. The cloth used was probably not the best choice for the application. This could be caused by using a fill oriented cloth in a radial application when it is intended for a cross cut application as I think Midland may have been referring to, (the cloth is being loaded in a direction that it is not very stretch resistant). It could also be from using a cloth that was a bit too light or just too stretchy for the application. That said, it really isn't that bad looking. A lot of OEM sails on production boats look much worse than that.

Jim

[Rafale]

Yep , creases are from biasstretch . What's the cause ?? There is more than 1 possible answer I think .

The sailmaker used horizontal hydranet in a triradial application instead of the radial product . ( how does the cloth feel , soft of hard ?? )
It is radial hydranet ..... but a bad roll . .
The battens are overtensioned in trying to overcome the problem... zones of deformation from leech to luff at the next following batten .
Upper 2 battens are too soft , or sail too full in upper quarter .
To much build in shape (in the seaming ) with battens tapered at 30% instead of 45 to 50 %
Or to much luffcurve at the top . (is simple to remove ) .

The good news .... creases will dissapear once you are sailing .

[s/v Jedi]

Ahhh.... I never realized that there are different types of HydraNet. My sails are very stiff, almost as stiff as the laminates I had before. But my sails are build bullet proof too, they are 3/8" thick between the plates of the headboard!

I see Spectra fibers both horizontal and vertical at about 3/4" distance, like a net. In addition to that I think there's also more spectra fibers for the "fill" of the weave which run vertical. I need to check panels in the middle to see how they are cut... maybe the fibers are still horizontal & vertical but I think the idea is that they run in the same direction as the panel because that is what tri-radial construction is about.

When I first saw the photo I thought that the tension on the sewing machine might have been wrong but the creases stop before reaching the seams.

ciao!
Nick.

[Steve_C]

If you tighten the topping lift do the creases get worse? or better? Changing the downward pressure on the the sail and noting the changes would tell a lot. I looks like the panels are not properly oriented to match your Mast/Boom geometry.

Just a thought...

[gav reloaded]

As a sailmaker I have encountered the problem you are having with this sail. Hydra net is a fantastic cloth although it does have a problem.
Basically when it is being seamed together the needle gets deflected when going through the parts of spectra in the cloth causing distortion, which is what we are seeing in the photos. The good news is that what your sail really needs is some decent breeze through it this should settle everything down. So go sailing in about 18+ knots upwind and you will have a good shaped sail.

[privileged]

thanks Gav . I have sailed in plenty of wind over the last twelve months with no change to the sail . So the sail maker decided to make a new sail for me thinking the cloth was faulty. And guess what after one week same creases appear.. so where to now. I dont know He now tells me that the cloth is not the right choice for the sail design with that amount of roach and that the performance of the sail will not be affected . we will see