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PostPosted: Fri Jun 21, 2019 3:21 pm 
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Location: Sydney, Australia
jere2x wrote:
I was under the impression that battens should be tight all the way up in light air to keep as much wind in the sails. The general consensus is don’t over sheet. I was definitely sheeted in way to tight.


I don’t change my batten tension ever. They are always in gently, just enough to take the wrinkles out. Never tie the battens in too tight. That is a mistake that will over curve the sail when it is under load.

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Hobie 18 Reimagined
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PostPosted: Fri Jun 21, 2019 3:30 pm 
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Location: Sydney, Australia
tedcool wrote:
I'll try:

A very soft but tight batten will be very curved. This will keep the leech in better all the way up, and make more of a pocket.

You might have to give the boom a shake to 'pop' the batten over when tacking / jibing.

Does this sound about right?

My second theory:

Soft batten allows the top panel to twist off more without taking the panels below it along for the ride.


First theory response: a soft batten will provide slightly more depth, which is what you want in very light wind but not in medium to strong wind. I don’t use a batten simply because it is soft or hard, it still also needs to have the right shape. A soft batten with the wrong shape can be more detrimental than a stiff batten with the correct shape.

The very top batten and 2nd batten should have 50% camber.
Batten 3 should have 45% camber
Battens 4 to 9 should all be 35-40% camber.
I don’t use a bottom (foot) batten. It does nothing and is a waste of time and money, although it does make a good spare in your sailbox. There is no other loose footed catamaran of the modern era that uses a bottom batten.

Second theory response: a flat or stiff batten allows the sail to twist off. A soft top batten keeps the depth in all conditions and makes the leech sit up with less mainsheet tension. Thus the reason why I don’t use a soft top batten in medium to strong wind. I use a standard or stiff batten for medium to strong wind to help the head twist off naturally under luff tension load.

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John Forbes
Hobie 18 Reimagined
Sail # 490
Boat name: 18@heart
http://www.hobie18.fun
https://www.facebook.com/Hobie18catamaran/


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PostPosted: Mon Jun 24, 2019 5:16 am 
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Location: Rockland Maine
Thanks John!

My theories were -carp- , but I learned good stuff from you - again!


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PostPosted: Tue Jun 25, 2019 2:42 pm 
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Joined: Thu Nov 03, 2011 9:33 pm
Posts: 30
Over sheeting, over batten tension and jerky helm.

I sail my 18 balance with waterline halfway up the bow up to 2" from the lip of the bow. If there are waves... move back till average is a couple inches down, and/or never breaking over the top of the hull.

I have been sailing with slightly looser diamonds that before, about 24" up the mast... event at 350lbs.

Batten tension, should be just enough to hold shape, but easy to pop over. I do this in light or heavy air, since learning this at a clinic, it has been very effective.

don't crank on the outhaul... you want some sail shape for power... don't crank on mast rotation... same thing, you need power.

last bit, is that I used to force the boat into a straight line... riding the puffs and working the apparent wind often means you don't get to sail in a straight line. Heavy air lets you get away with a lot of mistakes... when air is light, it's easy to screw up flow over your foils and sails, and much harder to get it to re-attach. A subtle but firm turn down when going to weather, or turn up when reaching to re-attach flow can help you get moving and ultimately better VMG.

Good luck.


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PostPosted: Fri Jun 28, 2019 11:12 am 
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Location: Buffalo, NY
moncasta08 wrote:
don't crank on the outhaul... you want some sail shape for power... don't crank on mast rotation... same thing, you need power.


I agree about the outhaul in light air, but the mast rotation... there's two schools of thought. The first, by keeping the mast rotation tight (less rotation), you're forcing the mast to bend on its major axis, which it doesn't like to do, so it remains stiffer/straighter, and forces the sail to develop more of a shape, giving you more liftin lesser wind speeds. However, you also create an "indentation" in the leeward side of the sail, where it meets the mast, causing potentially some disturbed flow/separation right at the leading edge, as the air transitions from the mast to the sail.

Conversely, letting the mast rotate more and keeping it loose will result in more mast bend and a flatter sail, but a more streamlined surface that will encourage the wind to stay attached better. If you don't oversheet, your mast won't bend TOO much, so you shouldn't end up with a terribly flat sail, but it's certainly a compromise. In light wind, I usually experiment with it. Sometimes I try less mast rotation, sometimes I try more, and see how it behaves. I haven't developed a hard and fast rule, but I generally prefer the streamlined entry point/leading edge. I think that particularly in light wind, that is more critical.

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PostPosted: Fri Jun 28, 2019 12:47 pm 
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Joined: Mon May 09, 2005 10:25 am
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Location: Jersey Shore
We run the same upwind rotation in all conditions. It has little effect on mainsail power - more important to have a smooth entry into the leading edge of the sail. You can tune power through mainsheet and downhaul settings, especially with the comptip.

sm


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PostPosted: Sun Jun 30, 2019 10:36 pm 
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Location: Sydney, Australia
srm wrote:
We run the same upwind rotation in all conditions. It has little effect on mainsail power - more important to have a smooth entry into the leading edge of the sail. You can tune power through mainsheet and downhaul settings, especially with the comptip.

sm


Me too. I only have three mast rotation settings. One for upwind (see my thousand photos on Facebook page) and one for reaching and overlaid marks (90 degrees) and one for downwind (100 degrees).

My mast rotation control is actually set up so when we pull it all the way in at the bottom mark, it can only go to one spot. That being, it blocks out at the correct spot, so the crew doesn’t have to look or think about it. They just pull it in and that’s it. I have a red ball as the stopper. (Mine is set up on the trampoline and the red ball hits the hole and that’s it. Set and forget).

Enjoy.

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John Forbes
Hobie 18 Reimagined
Sail # 490
Boat name: 18@heart
http://www.hobie18.fun
https://www.facebook.com/Hobie18catamaran/


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