Full Batten Main Sail.

Nov 4, 2018
155
Hunter 28.5 Catawba Island, OH
Just to make sure we’re talking the same language - Twist is the difference in angle of attack between the top of the sail and the bottom. More twist means that the top of the Sail is at a lower angle of attack (more “twisted off”) than the bottom. Too much twist means the top of the Sail luffs first. Is that what you’re seeing? It is generally desirable to have at least a little twist, because the true wind speed is higher at the top of the mast. It’s only really a problem if it’s excessive. If it is make sure you can get the boom down and that it’s not being held up by the topping lift. Also make sure you have the main hoisted completely. Assuming both of those are true then you should be able to pull the boom down with either the vang or the sheet to reduce twist.

Are there any wrinkles in the sail that could indicate funny shape?
Yes we are speaking the same language.

I have also contacted Cliff Rucksurahl, a PO of my boat (Four owners ago.) He also suggested I contact Ryan my sail maker. He is also suggested, willing to sail with me to witness my issue first hand. Of course, due to his coaching, I'm going to find out how bad a sailor I am.

As to what I'm seeing is this: An open twist with the top tail tale fluttering curving around to the downwind side of the sail.

I've tentioned the outhaul to eliminate wrinkles. I've also used the leach hem line to stiffen the leach. The result of all knowledge I have of sail trim leaves me with only an open twist (no twist) at the top of the sail.

Cliff asked me if the the sail was new. Yes, the sail is brand new; bend on the 6th of July. I do have issues with the batten slug hanging up when lowering the sail, and have sopken to Ryan about this. he has a slug that should eliminate this issue.
 
May 17, 2004
5,028
Beneteau Oceanis 37 Havre de Grace
n open twist with the top tail tale fluttering curving around to the downwind side of the sail.
A leach tell tale curling around the back of the sail means the sail is stalled. That means it’s too tight. If that’s happening at the top of the sail it means you don’t have enough twist. Ease the sheet or vang to increase twist and get that telltale flying out like the others. What you want is all the leach telltales flying straight back, without luffing at the front of the sail. Luffing means that part of the sail is out too far. Curling leach telltale means it’s too tight.
only an open twist (no twist) at the top of the sail
Stop saying that. No twist is the opposite of open twist. No twist means you’ll have a stall at the top of the sail, with leach telltales up high curling as you describe. Open twist means the top of the sail will luff, with upper telltales streaming back but a big backwinded bubble at the luff.

If the top of the sail is stalled you need to ease the sheet and/or vang to get that telltale streaming again.


I've also used the leach hem line to stiffen the leach
Try undoing that first. The leach line tends to put a curl in the leach which will cause flow separation there and could cause the telltale to curl forward like you describe. The leach line isn’t really a sail trim control; it should only be tight enough to keep the leach from fluttering. Any tighter and it distorts the back of the sail.
 
Nov 4, 2018
155
Hunter 28.5 Catawba Island, OH
A leach tell tale curling around the back of the sail means the sail is stalled. That means it’s too tight. If that’s happening at the top of the sail it means you don’t have enough twist. Ease the sheet or vang to increase twist and get that telltale flying out like the others. What you want is all the leach telltales flying straight back, without luffing at the front of the sail. Luffing means that part of the sail is out too far. Curling leach telltale means it’s too tight.

Stop saying that. No twist is the opposite of open twist. No twist means you’ll have a stall at the top of the sail, with leach telltales up high curling as you describe. Open twist means the top of the sail will luff, with upper telltales streaming back but a big backwinded bubble at the luff.

If the top of the sail is stalled you need to ease the sheet and/or vang to get that telltale streaming again.



Try undoing that first. The leach line tends to put a curl in the leach which will cause flow separation there and could cause the telltale to curl forward like you describe. The leach line isn’t really a sail trim control; it should only be tight enough to keep the leach from fluttering. Any tighter and it distorts the back of the sail.
Okay David, I'll stop using no twist. I do mean an open twist that I cannot close or induce any other twist into the top of the sail.

As, I've mentioned earlier, I've tried tensioning/easing the sheet and/or the vang, running the car high and low, tensioning and easing the backstay. The leach line was one of these, "What have I got to lose." deals. The same goes for the topping lift. Right now it is eased so the boom rides at it's lowest point (A bugger on the head if I'm not careful.).

That's what I can't understand. All main sail controls I've played with and I look up to find that when I should have a closed or partially open twist it's not there. I always have an open twist.

I should mention that the curling taletell to the lee happen only when I'm in a close reach to broad reach. To the wind all telltale flow straight as they should.
 
Nov 4, 2018
155
Hunter 28.5 Catawba Island, OH
I apologize for resurrecting this thread. However, it need a clean ending. Being landlocked also gives all of time to contemplate your navel.

I had been misinterpreting the pictures incorrectly. I should have looking at the parallelism of the top batten to the boom.

Call me stupid, but I found the error of my ways and will be correcting to look at rightly

Thanks all for responding,

Alec
 
May 17, 2004
5,028
Beneteau Oceanis 37 Havre de Grace
I had been misinterpreting the pictures incorrectly. I should have looking at the parallelism of the top batten to the boom.
Correct - the angle of the top batten relative to the boom is a measure of twist. Back of the top batten falling to leeward is lots of twist. Back of the batten up to Windward is less twist.