Full Batten Pressure

[wingover]

Hi,

I have a question about how tight the battens on the full batten main should be? Do you just insert them all the way and close the pocket, or you pull the string and have a little curve in the batten (pushing against the luff)?

Thanks,

Mike

[daddle]

Generally, minimum pressure for light winds. Just enough so they hold the draft curve. Stronger winds, tighter battens.

But in practice just enough 'to get the job done'. Whatever it takes to get the sail shape you want for the conditions. (How's that for a non-answer?)

[wingover]

For a non-answer? really good :-) I didn't think you change the pressure on the battens for wind condition. you do that with outhull and backstay.

[daddle]

No, you probably won't be changing the batten pressure as the wind changes. We did when racing...between races. You'll make adjustments for a while until the shape is good then leave it. I bet most sailors have the battens too tight.

Backstay and outhaul probably loosen the battens...because they tend to stretch the sail...but I actually have no idea...I trim for shape not some numerical value, mark, or control line feel.

[barnakiel]

In our main (which has some roach) I will make the battens just tight enough so that in very light wind conditions they will induce some shape into the sail when I pull on the main sheet. I believe this is rather tight than slack - but not overly tight.

b.

[donradcliffe]

On cruising boats, tightening th battens will cause more wear and chafe on pockets and slides--keep them loose.

[Palarran]

That's a good question.

I have a large roach and have noticed that when I'm in about 20 kts of wind, it (the roach) starts to bend backwards. I had been planning on tightening up the battens. Would that be correct?

[ggray]

Originally Posted by Palarran

That's a good question.

I have a large roach and have noticed that when I'm in about 20 kts of wind, it (the roach) starts to bend backwards. I had been planning on tightening up the battens. Would that be correct?

May be that the batten is not stiff enough. I got some fiberglass rod to replace a worn batten, thinking it was less expensive that I would have thought.It fell of to leeward more than the original, just as you describe. So it seems there is a difference between fiberglass rods for battens. Or maybe your battens aren't round?

[daddle]

Originally Posted by Palarran

...I have a large roach and have noticed that when I'm in about 20 kts of wind, it (the roach) starts to bend backwards. I had been planning on tightening up the battens. Would that be correct?

Roach bending to leeward? That sounds odd. Is the luff soft at the same time? Sounds more like a sail trim problem. Or a completely blown out sail. There normally isn't much leeward wind pressure on the aft part of a sail when properly trimmed.

[David M]

Originally Posted by daddle

Generally, minimum pressure for light winds. Just enough so they hold the draft curve. Stronger winds, tighter battens.

But in practice just enough 'to get the job done'. Whatever it takes to get the sail shape you want for the conditions. (How's that for a non-answer?)

For racing small catamarans it was just the opposite. More batten tension increases draft and less tension flattens out the main.

[s/v Jedi]

Originally Posted by David M

For racing small catamarans it was just the opposite. More batten tension increases draft and less tension flattens out the main.

That is how it works for us too

ciao!
Nick.

[Palarran]

Daddle - it could be a trim problem. But if it is, I don't know what I could do to correct it as I've tried traveller and main sheet adjustments quite a bit with no real change. The roach doesn't necessarily bend to leeward but more curves back to straight. Kind of like a ? shape. It could be normal, I don't know.
As David M wrote, I'm thinking I need more pressure to create more draft and keep the roach curved with the main. My telltails generally flow aft or waiver to leeward. There also us generally a fair amount of twist to the sail.

[daddle]

Palarran: Yes, maybe you need more batten pressure. That would fall under the rule "do what it takes to get the job done. But sails with a flat run at the leech tend to be old sails, too.

[daddle]

Originally Posted by David M

For racing small catamarans it was just the opposite. More batten tension increases draft and less tension flattens out the main.

I suppose if batten pressure is effective in controlling draft you might do it this way. Perhaps cloth stretch is significant. With my full batten North 3DL sails we loosen the battens in light conditions to make sure the sail inverts quickly on tacking. In heavier air this is not a problem so batten pressure is added until the wrinkles disappear.

So it could go either way. Do whatever works for you.