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Go Back   SailNet Community > Skills and Seamanship > Learning to Sail
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  • 2 Post By Sailormon6
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Old 11-26-2012
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Too much lee helm

Hi, I'm wondering if someone can please help me understand what I experienced today and how to fix it in the future. The wind conditions were very erratic - blowing hard then dying off (at one gust, I heeled to the point where I burried the rails and the end of the boom touched the water while sailing close reach before I could ease the main sheet) - so I decided to reduce the jib by about a third just to reduce sail area. I didnt think about reefing the main since half the time I wasn't getting enough wind.

I was expecting this will result in more weather helm but at one point, I got too much lee helm, I had to push the tiller as far as it goes to leeward just to maintain my course between beam reaching and close reaching. I got concerned that it will spin me around and/or cause an accidental gybe. I had the backstay, boomvang, and outhaul at slight tension and the jib track at middle position, which I thought were appropriate for the conditions.

Can anyone please advise?

Thanks!
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Old 11-26-2012
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Re: Too much lee helm

Generally, excessive lee helm happens when the Center of Effort of the sailplan is too far forward in relation to the boat's Center of Lateral Resistance. When sailing with both a jib and mainsail, reducing the sail area of only the jib moves the Center of Effort aft, so, it should reduce lee helm.

From your description, I can only speculate, but if you were luffing the mainsail severely while sailing on a 1/3 furled jib, that could have moved the CE far enough forward to cause lee helm. In the winds that you described, which were gusting hard enough to put the boom end in the water, it seems likely that you were luffing the mainsail to keep the boat on it's feet. Luffing the mainsail moves the CE forward, which reduces weather helm, and, in the extreme, causes lee helm.
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Old 11-26-2012
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Re: Too much lee helm

Its tough to sail in those conditions, and I don't know what kind of boat you have, so it is hard to give specific advice. You need to adjust your sailplan so that you can handle the maximum wind you are likely to experience, and suffer through the lulls. If you had reefed the main you might have been able to keep it trimmed properly and eliminated the lee helm.
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Re: Too much lee helm

With reference to my previous post, the remedy I would recommend is that, instead of luffing the mainsail, you bring in the mainsheet just enough so that only about 1 1/2 or 2 feet of the leech of the mainsail lays down smoothly. The mainsail will be backwinded, and a big bubble will appear along the luff of the mainsail. That small amount of pressure along the leech of the mainsail will help push the boat's transom to leeward, and to drive the boat closer to windward. The objective is to balance the pressures on the mainsail and jib, both forward and aft of the CLR.
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Old 11-26-2012
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Re: Too much lee helm

It's like Sailormon6 said. Let's break it down:

Quote:
Originally Posted by Lukewarm View Post
I heeled to the point where ... the end of the boom touched the water while sailing close reach before I could ease the main sheet)
Assuming this is accurate, either you were knocked down or your main was out way too far for a close reach.

If you were knocked down, you had enough wind to justify a reef.

If your main was out too far, I'm guessing you were doing this because sheeting in also made you too uncomfortable, which implies there was enough wind to justify a reef.

Also, having your jib sheeted in and your main luffing is a recipe for lee helm, so I'm guessing that's the culprit.

Reef your main and sheet it in.
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Re: Too much lee helm

Quote:
Originally Posted by Lukewarm View Post
... - so I decided to reduce the jib by about a third just to reduce sail area. ...and the jib track at middle position, which I thought were appropriate for the conditions.

Thanks!
An additional factor could be excessive pressure from an over-trimmed jib, IF the jib sheet block is too far aft. As you furl the jib, you need to move the block forward to maintain the proper sheet angle. The "middle position" may or may not be fine, you need to judge the jib and set the sheet accordingly. if the jib sheet is too far aft, while the top of the jib may be luffing, the bottom will be over-trimmed, the net result most likely being little drive and more lee helm.
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Old 11-26-2012
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Re: Too much lee helm

Quote:
Originally Posted by Lukewarm View Post
I had the backstay, boomvang, and outhaul at slight tension and the jib track at middle position, which I thought were appropriate for the conditions.

Can anyone please advise?

Thanks!
What probably/possibly happened during the gusts was that you became 'cross controlled' --- the forestay became slackened due to the elasticity of the wire and became curved WELL off to the lee side (because of the slack slight backstay tension) ... this causes severe degradation in the ability to 'point' (even during a close reach). Your boat was now probably skidding to leeward (which shows up as excess heel). You attempted to correct by releasing the mainsheet which caused a 'power-up' in the mid or top panels (due to increased curvature and deepening of the amount draft which 'relocated' more forward than normal). all 'cross controlled'.

Most 'cruising sails' are designed for usage in 12-15 its of wind strength, and the shape of the sails, especially jibs/genoas 'depend' on the tension of the forestay .... the sailmaker will ASSUME that you forestay is nominally at about 15% tension. At higher wind strengths the forestay stretches and the luff is now operating well to the lee side of the boat (apparent lee helm), when you correct by mainsail or rudder cross control .... the boat now begins to skid to leeward.
I think in this case and from the descriptions given, the MAIN problem was the forestay wasnt tight enough for the conditions at the time, and the center of the jib luff was wellllllll off to leeward (luff to leeward, draft great increased and the jibs leech section was 'hooked up to weather'. Since you apparently 'reefed' the jib (sail area reduction) did you ALSO move the jib fairlead car FORWARD so that the sail didn't become overly twisted (an aver twisted sail can suddenly power up, especially in 'gusts').

In especially gusty conditions and well above that 12-15kts design point what was 'cut' in your jib, you really need to increase backstay tension to match the 'worst' windstrengths at that time to avoid 'jib shape and trim problems'.
Heres a hint on how much backstay tension needed ... simply by watching how much 'curve' that forestay takes at max. wind strength (gusts). Once you get that amount of forestay curve under control, then all the CLR/CE stuff then can be assayed/applied.

How to detect a leeward skid: watch the stern wake, look for the zone of turbulence coming off the rudder at the stern .... if its not coming fairly straight off the boats stern (4-5° maximum 'off angle') the boat is either skidding to leeward (felt as 'weather helm' but isnt) or your 'weather helm' is actual (a 'sail shape and trim, etc. problem).

Heres how to assay the correct amount of backstay tension to have a sailboat have a fairly 'neutral' helm even in 'blammo' conditions. Just dont much above 30% backstay tension as thats where the stainless wire/rigging components starts to 'yield' and accumulates a LOT of fatigue. Once you go above 30% wire tension, you MUST reduce sail area/reef, etc.
A sailboat with a too loose forestay/backstay simply will not 'point', even on a close or even a beam reach.
Setting correct backstay tension -http://www.ftp.tognews.com/GoogleFiles/Matching%20Luff%20Hollow.pdf
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Re: Too much lee helm

Thanks to everyone for the advices. Really very helpful. Now that I look back based on your feedback, I think this is what happened. I had the traveler all the way to leeward to control heeling whenever a gust would come. Then I started to point higher so I sheeted in the jib and that was when the "knockdown" (is it a knockdown when only the tip of the boom touched water while traveler is way out?) happened so I sheeted out the main. I did sheet in the main again a little bit afterwards but that probably describes the condition I was sailing on when I had the excessive lee helm. I eventually managed to tack to go back from that area (the narrower mouth seem to cause a funneling effect from wind coming from the other side of that).

I didnt reef since I looked around and everyone had full mains up although I did see one boat bring down their sails in the general area I was having problems on but later saw their mains all the way up again. I looked up the a buoy's historical record near the area and it said mostly around 4 knts with occasional 12 knts gusts. It was how it felt to me too at the time too - even lulls of almost no wind - so I thought that was within the capabilities of a 22 footer without needing a reef.

Reefing aside, is it right to say that I should have sheeted out the jib a little bit and sheeted in the main some more in order to gain back more rudder control right away?

I've gone out before in 8-12 knts conditions but the big gaps in lulls and puffs in this case seemed to have made controlling the boat more difficult compared to the stronger but more steady conditions. Or is this just based on inexperience? I've only gone out 25 times since I started learning so it feels like being a raw beginner again in these conditions.
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