Excessive weather helm? - SailNet Community
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post #1 of 17 Old 07-22-2002 Thread Starter
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Excessive weather helm?

I have an AMF 21 which only has about 850lbs of ballast and I only day sail on local oklahoma lakes. On a typical windy day the winds here range from about 15mph gusting to 30mph. Even flattening the sails the best I can I will still heel about 35degrees on a close reach and will still suffer extreme weather helm. Should I get a larger boat (recommendations?) or just resign myself to reefing. Thanks all you salty dogs!
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post #2 of 17 Old 07-22-2002
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Excessive weather helm?

think of the boat pivoting at the mast and the wind coming from lets say port.
if both sails had the same force on them the boat would go straight.
if the boat wants to go to port ( weather) you have too much main.
if the boat wants to go too lee you have too much genoa. that is as simply as i can explain it.
eric
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post #3 of 17 Old 07-22-2002
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Excessive weather helm?

The previous answer is correct, but only part of the picture. To ''balance'' the weather helm, you need to either lessen the sail area on your main, or increase it on your head sail. Obviously, if you''re heeling 35 degrees and in 30mph gusts, you really don''t need any MORE sail up.

The other part of the picture is what''s happening under the boat, once you''re heeled over. Your keel (centerboard?) and rudder are no longer pointing straight down, making them less able to steer you out of the wind. In addition to that, the lee hull now has more drag on it, as much more of it is in contact with the water. All of these things will contribute to turning you up into the wind (which is not that bad a thing -- consider it a saftey net of sorts)

The best thing to do is reef the mainsail. It will reduce your heel -- give the boat more control, and you''ll actually sail faster. Remember, when your close reaching, the apparent wind is even greater than the 30mph gust, as your traveling into the wind.

Of course, a bigger boat is also part of a working solution... <grin>
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post #4 of 17 Old 07-22-2002
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Excessive weather helm?

Easing the mainsheet a little until the main just starts to luff will usually reduce weather helm. Of course reefing is always a good idea in that kind of wind.

Jim
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post #5 of 17 Old 07-23-2002
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Excessive weather helm?

These are very high wind ranges for a lightly ballasted 21 footer. You do have a number of options short of reefing. First of all in that kind of wind you should only be using a working jib (rather than a genoa as heeling is a part of the problem.) Next it is impostant to blade out your sails. That means on the mainsail, lots of outhaul, halyard and vang tension. It means a relatively tight mainsheet with the traveller eased to leeward. It means lots of backstay tension. At some point approaching 20 knots of wind, it will make sense to reef the mainsail. On a boat that size it becomes very important to be able to reef quickly and reliably on the fly. I strongly recommend that you have a two line reef system lead to the cockpit and that you keep a first reef ready to throw in.

On the jib it means moving the sheet lead aft a little, really tightening the halyard and lots of forestay tension.

On a centerboard boat you can raise the board a little to move the center of lateral resistance aft and further reduce weather helm (But this is not the best idea if your 800 lbs of ballast is in the form of a swing keel.)

Obviously getting weight up on the rail helps as well. Keeping the boat as flat as you can is important because on older boat designs as you heel the boat''s waterline becomes more assymetrical and morphs into a shape that tries to spin the boat into the wind.

Jeff
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post #6 of 17 Old 07-23-2002
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Excessive weather helm?

Jerry,

The time when you should reef is a judgment call. If the wind is blowing 15 mph with occasional gusts to 30, then you might not reef. If it is frequently gusting to 30, you should reef. When it gusts to 30, the boat is overpowered, but as long as the gusts are infrequent and brief in duration, you can ease the traveller and use the other sail trim techniques that Jeff H. and others describe. When the gusts are of longer duration and more frequent, it is time to reef.

This assumes that you are either racing or that you want to make the best possible speed for some reason. If you are cruising, or if you have non-sailing guests aboard, it is better to reef sooner. It''s a lot harder to reef the sail when the boat is already overpowered and heeling excessively.

You don''t say what size headsail you are flying, but a 150% is usable when the wind is at 15, but the boat is way overpowered when it is at 30. If you carry sails that are appropriate in size for the overall conditions, the boat will sail more upright, and it will go faster on average. From what I have seen, club racing sailors have a strong tendency to carry too much sail for the wind conditions. If you carry the correct amount of sail area, you''ll sail faster and point higher and beat them.
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post #7 of 17 Old 07-31-2002
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Excessive weather helm?

A couple of thoughts on weather helm.

#1 I agree with all of above. If you have weather excessive weather helm there is more force aft of pivot point than fore of it. Flatten, reef, ease main. All will help. In a gust esp ease the main and sacrifice the leading edge. This will help to orevent rounding uop.

#2 A friend had a 25 with some weather helm. He tuned the rig such that the mast was raked a little more aft. This reduced weatehr helm.

#3 A lot of discussion in Tanzer 22 circles is that the Spade type rudder standard with the boat produces weather helm. It has become a standard practice to replace the rudder with a more fin shaped rudder to help this.

Regards,

Mike
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post #8 of 17 Old 07-31-2002
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Excessive weather helm?

Jerry, the only thing I could add to the suggestions given is to adjust your traveller to weather side, to centre your boom down the axis of the hull. when you get overpowered, the jib will pinch and the main will still pull. This reduces rounding up: I do this on my Catalina 22 when I want to hold a course. when I want to claw to wind, I luff the main and let the hardened headsail take me upwind.
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post #9 of 17 Old 07-31-2002
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Excessive weather helm?

With all due respect, Mike, I suspect that your friend drecreased rake to reduce weather helm. Increasing rake moves the center of effort aft and increases weather helm.

On the follow-up post, I think that you mean that you drop the traveller to leeward which blades out the mainsail and reduces weather helm.

Jeff
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post #10 of 17 Old 08-01-2002
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Excessive weather helm?

Jeff H,
I move the traveller to weather and centre the boom when closehauled in overpowering wind on my C-22. Everything is in hard. When an overpowering gust hits and the boat begins to round up, it is the headsail that luffs and the main that stays loaded. This reduces the weatherhelm effects and leaves the mainsheetman with the option of still luffing the main, with the jib pinched and depowered, if the boat is still overpowered. I think it works because the jib and main are the same SA and the CR is balanced for that.
However I will try out your suggestion of taking the traveller to leeside too.
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