How to correct weather Helm - SailNet Community
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post #1 of 32 Old 01-03-2009 Thread Starter
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How to correct weather Helm

I have had my 32' ketch for 4 years now and am still trying to get it tuned right. It has a non adjustable Furler with a 150% Genoa on it for the front stay (can't be tightened.) When I got it the Stays were all very loose. It had good weather helm like that but was very sloppy because of the Stays. I tightened the stays all up which helped a lot but now it has way to much weather helm, almost unmanageable. My assumption is I need to tighten the front stay and loosen of the Back stays but how to best do this. Since there is no adjustment on the front stay I assume I have to either shorten it, which would be tough to do as it means messing with the Furler, or moving the mounting plate (whatever it's proper name is) at the Bottom of the front stay forward and putting a turnbuckle in for adjusting. Would doing that cause me other problems? Hope I explained this well enough.
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post #2 of 32 Old 01-03-2009
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You should probably do the other way around! ie tighten the back stay, which would also tighten the forstay, putting the mast slightly raked aft, which would put the CE of the sails back a bit, which should lesson the weather helm some.

You may also have to work with the actual tuning of the sails to figure out how to lower the weather helm too.

Have you looked at the rig tuning at the top of this area? While aimed at single mast boat, some of the how to may make making sure your tune is correct.

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I drives me dinghy!
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post #3 of 32 Old 01-03-2009 Thread Starter
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I think I am confused on this in the Rig tuning thread (and everything else I've read on this) he says "Aft Rake increases weather helm, improving pointing, forward rake does the opposite.My problem is that I have to decrease weather helm which would suggest to me that I need more forward rake. Before I tightened the Back stays The weather helm was good. I tightened them and got way to much. The more I tighten them the worse it gets.
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post #4 of 32 Old 01-03-2009
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Originally Posted by blt2ski View Post
You should probably do the other way around! ie tighten the back stay, which would also tighten the forstay, putting the mast slightly raked aft, ...
You'd think so, but it doesn't work that way, oddly enough. I had read that rake is solely a function of forestay adjustment/length, and that tightening/loosening the backstay doesn't affect it. "That doesn't make any sense," I thought. But then I tested it while adjusting our rig last spring. Sure enough: Tightening/loosening the backstay did not affect mast rake! Weird, but true.

superiorvoyager: Check Alex' (Giulietta's) rig tuning guide, Adjusting Your Rig, listed as a sticky at the top of the Gear and Maintenance sub-forum. (I'd just stick the URL in here, but Sailnet's stupid automatic link-a-word-to-crap-they-sell software destroys URLs that link to their own forum posts) and/or Ivar Dedekam's Sail and Rig Tuning. If you've too much weather helm, you do indeed want to reduce mast rake. Then again: You have a ketch, and everything I've studied is for sloop-rigged boats. I don't know how much of the above applies to a ketch-rigged boat.

How you can adjust mast rake with a non-adjustable furler is something I've no clue about. It sounds like "surgery" is in order, perhaps?

Jim

Last edited by SEMIJim; 01-03-2009 at 09:33 PM.
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post #5 of 32 Old 01-03-2009
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How about an adjustable "Chainplate" on the front stay? My front chainplate has multiple holes (fore and aft) to loosen or tighten the forestay. I'm not sure this would work, My experience is just on my little sloop.

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post #6 of 32 Old 01-03-2009
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It has a non adjustable Furler with a 150% Genoa on it for the front stay (can't be tightened.)
This may not be the case actually. Most furlers allow for forestay adjustment. It is usually a convoluted process requiring a certain amount of disassembly of the unit, but it should be possible. Google the manufacturer's website. If there are no manuals online there for your particular unit, email the manufacturer and ask for directions.

Weather helm increases with rake. As the center of effort moves back the boat will have a greater tendency to head into the wind.

When the forestay is loose, tightening the backstay will move the head of the mast back, thereby inducing rake. BUT as soon as the forestay is tight, shortening the backstay has the effect of bending the mast forward which flattens the belly of your mainsail.

If, after tightening the forestay, there is still excessive weather helm, try getting new sails, or having your current ones recut. A blown sail makes a big difference. If there is still a problem, then you could think about adding a short bowsprit to the boat.

Good Luck !

Last edited by Sailormann; 01-03-2009 at 10:16 PM.
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post #7 of 32 Old 01-03-2009 Thread Starter
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An adjustable chain plate is kind of what I was thinking. That would move the point where the stay ataches forward a bit but I supose that wouldn't hurt.
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post #8 of 32 Old 01-03-2009
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Quote:
Originally Posted by superiorvoyager View Post
I think I am confused on this in the Rig tuning thread (and everything else I've read on this) he says "Aft Rake increases weather helm, improving pointing, forward rake does the opposite.My problem is that I have to decrease weather helm which would suggest to me that I need more forward rake. Before I tightened the Back stays The weather helm was good. I tightened them and got way to much. The more I tighten them the worse it gets.
Superiorvoyager, you were correct to start--increasing rake, moving sail draft aft on the boat, would increase weather helm, as I think SEMIJim clarifies above.

I'm no rig tuner, by any stretch, but I would think you'd need to tighten the forestay to decrease rake noticably.

All that said, rake might not actually be the source of your weather helm problem. Weather helm means the draft of the sails is too far aft. Mast rake could cause this, but it could also be that the sails are too stretched out or not properly adjusted, resulting in mainsail draft that's moved after of where it should be. The solution if that's the case would be to have the main recut, if possible--replacement would be great too, but obviously much more $.

I would at least try sail adjustments (outhaul, leech, etc.) before pulling off the rolling furling unit to tighten the forestay. Just my two cents...

Good luck!
-J

P.S...added later -- Looks like others before me have posted pretty much what I did--I took to long to submit my post!

Last edited by josrulz; 01-03-2009 at 10:35 PM.
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post #9 of 32 Old 01-03-2009
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Weather helm can be caused by many factors or a combination of many. Too much forward rake and your boat won't perform well, too much aft and you'll increase weather helm. Sails, sail trim & sail condition are generally the biggest contributors to weather helm.

Perhaps if you can describe your rig, sail plan, stay configuration, brand of furler etc. etc. perhaps we can help you better...

I've sailed on a few boats that were just poorly designed and there was not much you could do to eliminate it other than expensive mods like a new rudder..

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post #10 of 32 Old 01-03-2009 Thread Starter
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I was assuming that the problem is in the rake since it started when I tightened the Back Stays. Problem is not in the sail adjustment (if it was adjusting would have helped. If I loosen the Back stays and let front and back stays just flop the weather helm improves but of course, the noise caused by stays tightning and loosing in the wind and waves, not to mention the stress put on the rig from all the jarring makes me think I shouldn't leave the stays slack. So I know I can get rid of the weather helm by having loose stays but obviously that isn't desirable. The front stay isn't adjustable so I need another solution. I don't have the manual here with me (It's on the boat under 4' of snow) but It says it was designed for use on a chainplate with a number of holes for fine adjustment. Otherwise it sugested sending back to the supplier and having it shortened. Right now it is on the farthest forward hole so I can't adjust it more. I can move the chain plate forward or make a new chain plate. I was planning on making an anchor roller for the bow of the boat so could possibly make a new chainplate/roller combination. My thought if doing this was to move the point of attachment forward and put a tunbuckle of some sort in so I can adjust it. This would move the point at which the bottom of the stay attaches 4-6" forward though and I have no idea if that would just cause more problems.
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