Bob Perry's take on Wolfenzee's dream boat - Page 68 - SailNet Community
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post #671 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

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Brent:
Really?
"Many clients have eliminated a heavy weather helm by eliminating the roach."

That's too bad that so many of your clients have had to deal with "heavy weather helm".
Some where I read that a battenless/roachless sail helps to reduce weather helm.....the theory being a less efficient sail gave less lift so there was less effort behind the center of lateral resistance. There are better ways to balance a rig.

There has been alot of knowledgeable data input on this thread, the best is from learned individuals having alot of knowledge in high tech coastal or semi-coastal racing sailing....this is great....though the sailing I am interested in is as an offshore cruising live aboard. I have been able to glean alot of bits and pieces that do apply to my boat though....thanks again.
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post #672 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

Wolfer:
Yeah, you probably read that in something Brent wrote.
I once read about a pig nosed baby in National Enquirer. It was BS. But it was printed.

I think that having battens in a sail lets the sailmaker control the max draft and foil of the sail. Without out battens you just get a "bag o'wind" The key is to move the center of pressure forward in the mainsail and keep the last 30% of the chord running almost straight. (Come on Jeff, draw a picture for me please) This has nothing to do with a simplistic 2 dimensional represention of your sail plan. This is a 3D real world situation. If you can control max draft and move the center of pressure forward you will do more than fooling around with a catcher's mitt main shape. Of course if you are struggling with a battenless main any effort to move the center of pressure forward will help. But that is a bandage on a wounded design.

There is no sailor in the world interested in good performance that uses a battenless mainsail. I know that ids a bold statement and risky but I belive it to be correct until proven wrong. Now we can argue the definition of performance but if you mean VMG over a wide range of conditions than I am correct.

If you want to talk about cruising the world with a 30 year old mainsail then I am not your guy. Talk to Brent he's very big on cheap.

You are welcome. It is your never ending quest for knowledge that drives this thread.
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post #673 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

I don't have time for this silly "your theories" and what's "trendy". What a crock.

I have been busy downloading recipes for coleslaw sauce.
I do have my priorities.

Here Brent , just for you.
You might call it a slow cooker. I call it a crock.
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post #674 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

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Reinforced leach tape really would not help at all. Its not the leech tape that wears out. What happens is that the leech is unsupported by battens and so the fabric itself is under higher loading and stretches. That results in extra material in fabric at the leech, which makes the leech want to flap. So, to keep the leech from flapping, the leech line is over-tightened, creating a hook in the leech. That hooking results in greater loads on the adjacent fabric forward of the hook, making the hook progressively bigger. The resulting hooked leech means more drag, weather helm, less projected sail area, and more heeling. To avoid that you need to somehow reduce the loads in that area and that is what battens do. They spread the loads into a larger portion of the sail....


In fact, when a sail gets old and tired, with bad flying shape, its ususally because the leech has stretched moving camber aft. The typical trick to get more life out of an stretched sail is to add full length battens.

Jeff
Then why doesnt that happen to your battenless headsail?

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post #675 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

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Some where I read that a battenless/roachless sail helps to reduce weather helm.....the theory being a less efficient sail gave less lift so there was less effort behind the center of lateral resistance. There are better ways to balance a rig.

There has been alot of knowledgeable data input on this thread, the best is from learned individuals having alot of knowledge in high tech coastal or semi-coastal racing sailing....this is great....though the sailing I am interested in is as an offshore cruising live aboard. I have been able to glean alot of bits and pieces that do apply to my boat though....thanks again.
You are right!
Everyone I know who has eliminated his roach has drastically reduced his weather helm. Theorizing on how the sun rises in the west and sets in the east, wont make it true, no matter how much math and theory you use to prove it. I prefer experience over such theory.

Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"
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post #676 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

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Originally Posted by Jeff_H View Post
Reinforced leach tape really would not help at all. Its not the leech tape that wears out. What happens is that the leech is unsupported by battens and so the fabric itself is under higher loading and stretches. That results in extra material in fabric at the leech, which makes the leech want to flap. So, to keep the leech from flapping, the leech line is over-tightened, creating a hook in the leech. That hooking results in greater loads on the adjacent fabric forward of the hook, making the hook progressively bigger. The resulting hooked leech means more drag, weather helm, less projected sail area, and more heeling. To avoid that you need to somehow reduce the loads in that area and that is what battens do. They spread the loads into a larger portion of the sail....


In fact, when a sail gets old and tired, with bad flying shape, its ususally because the leech has stretched moving camber aft. The typical trick to get more life out of an stretched sail is to add full length battens.

Jeff
What I found out wears the quickest is the stitching on the seam ends, which leach tape spans, eliminating a sudden horizontal rip along the seam. That is why a leach tape got me an extra 3,000 miles out of a 12 year old mainsail, in squally, strong, trade wind conditions.

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post #677 of 1155 Old 06-20-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

To me, if one needs to reduce the sail area, or leach, something was probably not designed correctly in someway shape or form!

I'll take my 2 full/2 partial batten main over my smaller 4 partial main any day of the week....

If in Wolfs shoes, I would not look for a used main, I would buy a new one. A jib, yes one can find really newish ones that are not blown out. Most racers can legally only replace 2-3 sails a year, so it is usually the jibs, spin then main. So a race main is toast many times comparatively speaking.

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Re: Bob Perry's take on Wolfenzee's dream boat

That's the whole point. Sheesh!
The leech tape stays hard and the rest of the sail bags out. The more you reinforce the leech the worse it gets without battens to tak3e that curl out.

It's like some of you have never looked at a sail uner load before. This is not "theory". Any sailmaker can tell you this.

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Re: Bob Perry's take on Wolfenzee's dream boat

Given that Wolfie wants to go offshore and be SAILING for a number of years I think it is false economy to try and re work a used sail. By the time he runs around finding a decent one, recuts, stitches, adds, subtracts battens, I'll bet the cost is pretty close to a new main sail. Try looking at an off shore sail maker with a good reputation, Tasker, Lee etc.

Understand the budget considerations, however, your mainsail is at the heart of what you are undertaking, sailing offshore!


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Re: Bob Perry's take on Wolfenzee's dream boat

I design all my rigs for a roachless main. It's only when they get disinformation from others that they screw up. One sailmaker I knew had an old couple come in with a bagged out main, and couldnt afford a new one. So he sewed a warp oriented , full width panel, the full length of the leech on. He said it set beautifully after that, and they got many years of good sailing out of it.

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