Usually, on sails designed for shortboarding there is a limit to how much leech tension you can give: if you give them less DH ( = tighter leech) than what they are designed for, the batten will stick around/behind the mast and the sail will not rotate.

I was thinking that I could perhaps modify my sails for a tighter leech ( and less DH) without compromising the rotation, if I cut he central battens by 1 or 2 cm, so that they move 1-2 cm forward and away from the mast, before DH, instead of hugging it too much. Right now, these batten, before DH, are almost half way along the mast circumference, towards the back. For proper rotation, I have to give a strong DH. Then the sail rotates perfectly, but the leech becomes too loose and the sail loses power in light winds...

My aim is to improve the light-winds performance of my Bic Core 293, by making do with the sails I have . I have an Ezzy Freeride 7.5, definitely too small for a shortboard in light winds..I also have a Severne Focus 8.5 , a bit better, but still not off the hook for subplaning.. Probably a 9.5 or larger will do, but I don’t want to go into such large sails because they become too heavy and hard to handle. Can the batten be shortened as outlined before? Maybe this will affect the shape of the sail, but in the Ezzy sails the shape is already built in the central panels, so modifying the length of 2 batten by only 1-2 cm should not be a problem. Any comments on this?

Thanks

Francone

I'm no expert but I don't think modifying a sail design is a great idea.. I had a sail that the designer had shortened the battens on to presumably give better low down power but I was never happy with its upwind performance ( don't know if the 2 factors were related though).

Francone, do you live in wa, Australia? And you need that size gear. Wait for some wind, downhaul the suckers and get that leech flopping.

Before you alter the sail you might try it on a hard top mast, assuming the sail you want to use is the Ezzy.
It's designed for a 12% (true constant curve) bend, but with tolerance for a more hard top.
A hard top mast will be softer in the bottom and stiffer in the top, so the sail will set with more bend in the bottom for batten rotation and a tighter upper leach. This is essentially what Ezzy recommends when he recommends using the bottom of a short mast and the top of a longer mast.

If you really want to shorten the battens what you have to do is shorten the batten pockets at the luff end. That involves unpicking the stitching and restitching it with the pocket end moved say 20mm. It sounds simple but it's fiddly. You'll need a sewing awl, or a few hours of a sailmaker's time. I've done it in the past with no appreciable difference in performance. Once the sail is full of wind the entry is smooth.

IF you really MUST do this experiment ...
a) try the hard top mast suggested
b) get some old battens from auventfou and play with their lengths
please do NOT cut the original battens !!
keep them as your fall-back ...
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in REALLY light wind it does NOT matter if battens flip to other side
you still get a good pocket of wind with the tight leech

raceboard sails are available in small sizes and can be set with tight or loose leach by downhalling and still have good rotation.
Try Starboard Phantomsails, Bic Techno, Neil Pryde RS One.

Shortening the battens w/o shortening the batten pockets as well, will result in vertical wrinkles in your sail, ruining it's efficiency.

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Francone said..
Usually, on sails designed for shortboarding there is a limit to how much leech tension you can give: if you give them less DH ( = tighter leech) than what they are designed for, the batten will stick around/behind the mast and the sail will not rotate.

I was thinking that I could perhaps modify my sails for a tighter leech ( and less DH) without compromising the rotation, if I cut he central battens by 1 or 2 cm, so that they move 1-2 cm forward and away from the mast, before DH, instead of hugging it too much. Right now, these batten, before DH, are almost half way along the mast circumference, towards the back. For proper rotation, I have to give a strong DH. Then the sail rotates perfectly, but the leech becomes too loose and the sail loses power in light winds...

My aim is to improve the light-winds performance of my Bic Core 293, by making do with the sails I have . I have an Ezzy Freeride 7.5, definitely too small for a shortboard in light winds..I also have a Severne Focus 8.5 , a bit better, but still not off the hook for subplaning.. Probably a 9.5 or larger will do, but I don’t want to go into such large sails because they become too heavy and hard to handle. Can the batten be shortened as outlined before? Maybe this will affect the shape of the sail, but in the Ezzy sails the shape is already built in the central panels, so modifying the length of 2 batten by only 1-2 cm should not be a problem. Any comments on this?

Thanks

Francone

You do realise that when a sail without cams is rigged "properly" that the batterns are supposed to sit somewhere around half way behind the mast. Right?

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qldnacra said..
You do realise that when a sail without cams is rigged "properly" that the batterns are supposed to sit somewhere around half way behind the mast. Right?

That depends on the brand.

ie: the KA Kult's require enough downhaul so that the batten is just free of the trailing edge of the mast.... without this much downhaul, the leach is tight, the sail feels dead and unresponsive.

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NotWal said..
Before you alter the sail you might try it on a hard top mast, assuming the sail you want to use is the Ezzy.
It's designed for a 12% (true constant curve) bend, but with tolerance for a more hard top.
A hard top mast will be softer in the bottom and stiffer in the top, so the sail will set with more bend in the bottom for batten rotation and a tighter upper leach. This is essentially what Ezzy recommends when he recommends using the bottom of a short mast and the top of a longer mast.

If you really want to shorten the battens what you have to do is shorten the batten pockets at the luff end. That involves unpicking the stitching and restitching it with the pocket end moved say 20mm. It sounds simple but it's fiddly. You'll need a sewing awl, or a few hours of a sailmaker's time. I've done it in the past with no appreciable difference in performance. Once the sail is full of wind the entry is smooth.

I took the bull by the horns and I did the modification with an old sail somebody gave me but I hardly ever used because it is too small for my usual wind range. It is an old cammed Sailworks Race 5.6. It is a Flextop 22-27 IMCS. First, I removed the cams because they didn’t work properly.( They slid off the mast inside the sleeve all the time and they were sluggish to rotate). Then I shortened the 3 main cammed batten to bring them forward and away from the mast by 6” so that they now intersect the seam of the mast sleeve which runs from the top to the bottom tack of the sail. I then restitched the batten’s pockets for the new shorter length.
This should allow me to give an even tighter leech, if required, while still allowing the sail to rotate. In the end, I hope to extend the light wind range of the sail..
I’ll see the results next summer because now we are in the dead of the winter here. If it doesn’t work, I’ll have nothing to lose. If it works, I’ll’ do the same with my Gaastra Pilot 6.5. If I can extend the light wind range of both these smaller sails, then may be I won’t need to use or modify the larger sails any longerin order to subplane comfortably.I'll post the results when available.

Francone.