light wind rigging quandary

ittiandro · Joined: 22 Nov 2009 Posts: 294

I am mostly subplaning because of the prevailing conditions here and my aim is to maximise the lightwind capability of my gear , by compensating, if at all feasible, the inherent bias of modern equipment towards strong winds sailing, speed and, ultimately, planing.

Regarding the sail, I had always thought that, for maximum power, it should have a fuller profile ( a deeper pocket) in its the lower part and forward of it, towards the mast. . Here is supposedly where the center of effort of the sail should be located for optimal (light wind) performance and this fuller profile would be attained by increasing the DH tension, in combination, of course, with the OUTHAUL adjustment. .

I am however a bit puzzled, because http://www.boardseekermag.com/news/awt-day-2-light-wind-rigging-josh-stone/6/#0oBRULi7HTVScPDt.97 gives a different story. It is said there that in order to give a fulller ( deeper shape ) to the sail, the DH should be slightly DECREASED, not increased!

I also read in one of the forums that one way to deepen the profile in the lower sail (and to shift the center of effort even more forward, closer to the mast ) would be to stiffen the batten above the boom) by inserting a 2nd shorter half batten in the pocket, at the leech end. The flattening of the sail on the leech side would amplify and shift even more forward the full profile of the sail.

I wonder if you or anybody can comment on all this.

Thanks

Ittiandro

gvogelsang · Joined: 09 Nov 1988 Posts: 435

The boardseeker article is correct.

Ease up on the downhaul, perhaps until there are "almost" wrinkles on the luff of the sail.

Ease up on the outhaul to put more pocket in the sail.

I sure wouldn't put a stiffer batten in the sail. The battens are stiff enough, and you want everything softer for light wind.

ittiandro · Joined: 22 Nov 2009 Posts: 294

PeconicPuffin · Joined: 07 Jun 2004 Posts: 1830

Note that if your intention is to plane, your sail must still have a floppy leach in order to plane in the lightest winds. The full pocket is great, but the wind still needs to be able to slip off the sail easily to develop lift. It's a common mistake to kill the floppy leach (your exhaust, if you will) in pursuit of power. If you're not looking to plane but instead are simply nonplaning sailing (ie longboard on a lake for fun) then don't worry about the leach.

Without the leach venting you'll feel a lot of tug from the sail, but it will take much more wind to shove you onto a plane.

U2U2U2 · Posted: Sat Jan 24, 2015 9:59 am Post subject:

100% agrree with those who posted above. I would not try to improve performance with a batten change, on any sail that is modern and try to outengineer the maker/shaper

There will be a point where down/outhaul adjustments will have diminished return, the sail will not perform.

isobars · Joined: 12 Dec 1999 Posts: 20935

I use the DH to tune foil stability, my sail size to macrotune sail power, and my OH to microtune sail power. Long before I'd start changing battens to overcome the sail designer's expertise, I'd just buy a bigger sail, buy more neoprene if my wind were better in the winter, buy a Jetski, and/or move to a windier location. There are plenty of sails out there designed by experts for maximum low end power.

ittiandro · Joined: 22 Nov 2009 Posts: 294

adywind · Joined: 08 Jan 2012 Posts: 665

Hi Ittiandro , take a look if you want at the last 4 comments in this discussion and tell me if your case is similar.
http://www.iwindsurf.com/forums/viewtopic.php?t=29450&start=10

coachg · Joined: 10 Sep 2000 Posts: 3550

isobars · Joined: 12 Dec 1999 Posts: 20935

Amen.

How about rather than cruising, fit your goals to your conditions and go instead for light air freestyle with a big platform and smaller sails?