Lee helm in light airs

[surekandoo]

My boat, a 24' fractionally rigged Feeling 720, exhibits slight Lee helm in light airs, say 7 knots of wind or less.

Whilst not in itself a problem, I'm puzzled as to why this occurs.

As the wind increases, the helm goes neutral, and at 12 knots there is some manageable weather helm which is as it should be.

Any Suggestions?

 

[pampas]

lay the mast slightly aft this should decrease the lee helm, trial and error I`m afraid.

 

[mrming]

What sail trim adjustments are you making? Light weather trim (slack halyards, straight mast, car forward etc will move the draft forward in the sail and as a result move the boat's centre of effort forward in relation to the centre of lateral resistance.

Could just be enough to cause it? I wouldn't touch the rake if you already have weather helm in heavier winds.

Incidentally what angle of heel are you sailing at in each case? Leeward heel causes weather helm, windward causes lee helm.

 

[Seajet]

My Anderson 22 is just the same, in very light airs with the No.1 Genoa she has slight lee helm; it's a simple function of the slight wind on the large sails having more effect than the ' foils ', the keel and rudder, as there's insufficient water flow over them.

I find the trick is not to sheet in too tightly, set her up for a fine reach and be gentle with sheets and tiller; then as speed is gathered, the helm balance recovers to neutral then slight weather helm and one is sailing again.

If you still have lee helm even when the boat has got going at over say 2 knots, maybe the rig needs raking aft a touch, as said trial and error but best in small increments.

 

[mrming]

Interesting Seajet - my boat points lower and makes leeway rather than displaying lee helm in very light winds, but definitely displays the low flow over the foils effect. Once the wind comes up slightly and the skinny keel starts generating lift then she starts to point and stops falling to leeward. I always heel to leeward upwind in light weather so it's possible that is counteracting any lee helm I might otherwise feel.

 

[Seajet]

mrming,

I heel my boat to leeward a little; notably she also has a fairly skinny keel, though she's quite directionally stable once she gets going - relatively large spade rudder with a smallish but still significant skeg.

 

[Javelin]

I assume you are talking about lee helm when close hauled ?

If so my bet is you have either not got the boom on or slightly above centreline or you have too much twist in the main.

The pandora has a similar tendancy due to the small main and relatively huge genoa.
The cure here is to power up the main as above and ease in the genoa as you get up to full boat speed after a tack.
i.e. don't get the genoa in all at once after a manoeuvre, progressively bring it in as you get up to speed.

 

[fishermantwo]

I had a similar problem with my quarter tonner. Raking the mast aft had little effect and I ended up making a new boom about 18 inches longer. Cut down mainsail off eBay. The boat was transformed. Light weather helm at all times and much faster, especially reaching and downwind. The larger mainsail while not fashionable in the era of IOR influenced vessels is more practical.

 

[mrming]

I noticed the Feeling 720 has a slightly unusual rig with fore and aft lowers:

Presumably this means inline spreaders so you can get the main out further downwind?

Anyone care to comment on what the downsides to this rig are?

Seems sensible to me in theory but I haven't actually seen it a lot in practice.

 

[William_H]

I would think this rig as depicted would essentially act like a mast head rig. This because as you crank on the backstay tension the mast is not going to bend very much because forestay is attached relatively close to the mast top. Of course any mast bend in stronger winds will be beneficial but don't expect too much. The fore and aft lower shrouds wou;ld also tend to locate the middle of the mast quite rigidly as in a mast head rig. Good points are no inner forestay to foul jib tacking and robust rig.Bad points compared to a flexible fractional rig are same as mast head rig. ie not so much flattening ability and no ability to allow top to fall away on the mainsail with mast bend in gusts. olewill

 

[Hypocacculus]

Interesting article here:

http://www.goodoldboat.com/reader_services/articles/Helm_balance.php

 

[jwilson]

I find the trick is not to sheet in too tightly, set her up for a fine reach and be gentle with sheets and tiller; then as speed is gathered, the helm balance recovers to neutral then slight weather helm and one is sailing again.

+1 - this is the key to getting any boat moving nicely in light airs, every tack you have to sail well free to start with and slowly slowly sheet in and point up as the speed builds. Add in a bit of bow-down trim and leeward heel if you can in really light wind. Bow down trim lifts the stern and quarter and reduces wetted surface drag, the leeward heel helps take out the lee helm and holds the sails in a nice curved shape instead of flapping. And move around slowly on board, don't shake the airflow out of the sails with sudden movements.

Lee helm in very light wind is common, better that than excessive weather helm in moderate winds.