Sorry to be an ignarmous 
but the newer sails have 2 holes at clew?? where the boom is attached around 25 mm apart. for what purpose?
Also on downhauling the sail I am getting diagonal creases, radiating 45 degrees from the bottom of the sail. Battons not tight enough? Too much down haul ? not enough?
I can only go on what I read in the setup of my new Severne NCX. From memory it says the using the top of the 2 holes on the clew will allow the sail to develop a little more power and the lower hole gives a little more control.
As for the creases, maybe someone with a little more knowledge can help you with that. My sails suffer more from the indentations created when I face plant them 
The two holes are for high and low wind speed.
So it goes like this.
High wind speed then boom rope goes in bottom hole
Low wind speed, boom rope in high hole
Low hole for high wind and High hole for low wind
Hope this helps.
45deg crease in sail bottom panel, I cant answer, some Guru will come back I am sure.
Regarding creases, it sounds like you're not downhauling nearly enough.
Are you sitting down with your foot on the mast foot, with a loop tied in the downhaul, a screwdriver threaded through this loop, and pulling back on that screwdriver like an olympic rower?
New sails need so much downhaul you'll think you're about to break something.
The leech should go really floppy - this tells you it's rigged right.
What sail and mast are you using? Is the mast fibreglass or carbon?
An easy rule of thumb. Down haul the sail til the 3rd(from top) Batten is pointing towards the middle of the mast and not sitting behind it.
and I agree with NEB's. Sounds like not enough down haul
It may be best to try the sail maker's website for rigging instructions. I know for Ezzy sails this works a treat.
Use the measurements on the sail. These are pretty close, most of the time
If mast length printed on the sail is 446 cm. You need 16 cm of extension if you are rigging on a 430 mast. The only complication, if you have a vario-top (adjustable strap at top of sail), this must be tightened, so no (or very little) mast pokes out the top of the sail.
Boom measurement is there also, but sounds like a downhaul problem to me also...
thanks guys for input.
Why would 25 mm height on the boom make a difference to the sails performance?
Sail 8.5mtr Gaastra GTX
Mast - Sailworks carbon 2003
I always worry that I will downhaull the sail too much. Use a puller to tension it. Dont know what damage I would cause if I did? lol
Have not tensioned the battens since I have got it ie - factory settings.
The 25mm HEIGHT does not make a difference. The difference comes from where the outhaul is pulling. If in the higher hole it tightens the leech a little (I'm told). I can't see it works much, better to tune off downhaul according to wind I reckon.
Then again if you are very tall having a higher hole is helpful i guess... keep the boom more perpendicular to the mast
As for how much to downhaul: A good rule of thumb for many sails is to downhaul until the floppyness between the top batten and second batten extends at least halfway toward the mast. Imagine the square formed by the top batten, leech, second batten, and mast. The rear half of that should be floppy.
That would be about min for a GTX. Then after applying that much downhaul, apply about 3cm outhaul from the neutral pozzie.
I dont think your ment to use the north crank (old man tools) on wave sails only.
Because they are put under too much stress with slalom sails.
I reckon they are great! but wayyyy to expensive!
From what I've been told about the two holes, the top hole tightens the leech which gives you more power and the board will point higher and the bottom hole gives you a more controllable and softer ride if the conditions are gusty.
I also give the downhaul rope a hefty pull. Haven't broken a rope yet but sometimes think I might.
Gents,
We have been here before, I called BS then, and maintain my position. I cannot see how 50mm vertical difference makes any significant difference to leach tension at all, especially given that the only way a force can act at that location is vertically anyway. I did the maths and it does not add up.
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=24551&SearchTerms=tension
JB
One thing having 2 holes IS good for is running an adjustable outhaul without the bother of a pulley block. But you do have to thread it every time you rig.
i'm voting for the 2 clew position working.
bottom hole for overpowered
top hole for light wind
works for me.
even with my sail dry i can see the difference at the leach.
In regards to the diagonal creases this extract is from the the "Guy Cribb" website.
"These diagonal creases are known as `breaking' in the world of sail testing and R & D and are a result of twisting (next time you wring towel dry, note the diagonal creases from twisting). If breaking occurs in every panel it's a sure sign the sail is twisting off evenly, which is good news. One of the resons sails have battens is to iron out these wrinkles to cause less drag, especially important for race sails."
Sounds good to me since my sail breaks from the clew panel diagonally up - and I rule at rigging....
AB....
I think diagonal creasing in the sail when fully loaded with wind is a good sign the sail is rigged correctly. I may be reading Old Salty's post wrong but I think he means when not loaded ie. out of the water lying on the ground. I apologise if that's not the case.
i think also that diagonal creases should run down from luff to leech at around 45 degrees or so and occur between battens.
if the creases are running from the bottom of the sail and upwards (near the downhaul) then it may be a mast shape issue.
this is a photo of a sail breaking.... and as ejmack says only under load
Justin, remembering the day that pic was taken, the sail should have been folding back on itself.
With the GTX, I found for mine (6.5 and 7.5 2008 GTX) You can downhaul them heaps. Go a bit over what the printed measurements are, this always felt fastest to me. This was using a Fiberspar Reflex 7000 100% carbon mast.
I found that the GTX didn't look to go quite as loose in the leech as some other sails, but I always had it loose between the top 3 battens. I rearly changed this as it seemed to be the sweet spot no matter the wind strength. I geneally used the top hole on the outhaul, and with full downhaul on varied between +1 and +3cm depending on wind strength.
Best thing to do is play around with the settings a little, It took me a while to get the sails really dialed in, but once there they felt really good.
Are the makers specs different on the two hole thing as I'm pretty sure the severne S2 6.4 I've got is bottom hole for power/light wind and top for speed/higher wind - thats what I do and it handles a pretty good range.
Need to look at the rigging guide again
on a 70lt wave board and didn't really sail that much in the end. wish it was the 4.2
