Sail Trim & Rig Tuning
Since other factors affect weather helm, think about the wind speed at which the problem starts, what size headsail you have, what type of keel, and/or the condition of the sails. Start out flatening and de-powering the main by tightening the outhaul to the max with just enough main halyard tension to keep the luff straight but not pull the draft forward. If you have a backstay adjuster tighten it next to flaten the main further. Trim the jib flat with all teltales breaking at the same time. The flatened main combined with a 135% or smaller Genoa should be a good combination up to 15-18 knots windspeed close hauled, after that tie in the first reef to balance the boat and reduce weather helm. Drop the traveler down to leward in the puffs, and change down to a 110 jib as the wind increases. Hopefully you can flaten and trim the sails to have one 'spoke' of weather helm on the wheel. If not, try to tighten the headstay and loosen the backstay(s) to bring the mast more vertical but with the same prebend in the mast. If that still does not do the trick, you might try a little more bend in the mast by tightening the upper stays. This will take some of the depth out of the main the same way a backstay adjuster works. If your boat was produced with both a shoal draft and deep draft version, the shoal draft may promote weather helm earlier because it's center of lateral resistance is further aft, therefore the mast should be almost vertical with very little or no rake. If you've tried a this and still have too much weather helm, you may need a new mainsail or at least a re-cut main.
