| |
You are here: Experts > Recreation/Outdoors > Surfing/Bodyboarding > Surfing & Windsurfing > Rotational sail
Expert: Windlover
Date: 8/28/2008
Subject: Rotational sail
Question
Hi !
I have just bought a a 7.6 Mistral RAF sail ( 2nd hand),on consignment at a dealer. It is probably a few years old, but for some reasons looks like it has been seldom used.
Yesterday I tried it out on my Starboard Rio board , but I noticed it rotates with difficulty. True, the wind was light, but even by " pumping "it against the wind ,it sticks . At first I thought it was because the batten were hugging the mast too much around it and I tried to give more out-haul tension, but things didn't change too much. Besides, I think I should be able to use the sail with less out-haul than that,for more power. I even tried to pumnp the sail on land by holding the rig vertical on the ground, but still it wouldn't rotate properly. Actually, it seems that the luff is sort of twisted around the mast, so that some of the batten have swung to the other side, but some stick. I also notice that the tip of the batten seems to exert a lot of pressure on the luff at the end of the sleeve, as if they were ready to tear through the fabric..
Are they perhaps too long ? I am sure that the sail would rotate with a very strong winds, but shouldn't it rotate with normal light-moderate winds as well?
Any comments or suggestions ?
Thank you
Franco
Answer
Hey Franco,
There are at least two specific reasons for your sail not rotating.
The first would be not enough downhaul. If you don't downhaul the sail to at least the recommended luff length, then the battens will overlap the mast. With enough downhaul the luff of the sail will tighten up and pull the battens away from the mast.
The second reason would be too soft or too stiff of a mast for the sail. With too soft of a mast and the right amount of downhaul, the battens won't pull away properly. If the mast is too stiff, you may not be able get enough downhaul to pull the battens away.
So, check the luff length printed on the sail. Verify your mast is long enough with the added length of your mast base extension (ie; recommended length is say 485 and you have a 460 mast, then your base extension should be set ~ 15cm.).
Next, check the stiffness recommended on the sail. It should say something like 25 or 28 MCS. If your mast is one number above or below the recommended MCS, then you should be okay. If it is two or more different, then your mast might not work properly.
If your length and MCS are close, then add more downhaul and see how that works. Watch the top two battens while downhauling to see if they pull away. Keep downhauling until this happens and you should be okay.
Adding outhaul will help some but try setting your outhaul at the recommended setting first. Then add a notch or two to see what it does to the battens. But, the main thing that will affect battens will be the downhaul.
As a last note, the battens are designed to be a specific length for the sail. Unless someone has changed all the battens (fairly unlikely), they should be what was designed for that sail. You should also keep the batten tension tight enough to remove any wrinkles in the batten pockets and the sail itself.
Also, RAF sails historically require a bit more downhaul than the recommeded settings to get proper rotation. Not always, but quite often this is the case with RAF sails.
Hope this helps.
Keep on sailing,
Windlover
Add to this Answer
Ask a Question
|
|
