Study Hall: Correcting weather helm

[Alan Wheeler]

An excellent note on Weather helm authored by GordMay

Poor balance (Weather Helm) increases as the “Centre of Effort” moves aft of the “Centre of Lateral Resistance”, and can also be caused by warped rudders, skegs, and keels/centerboards, or even by baggy sails.

Sail trim to move the C of E forward, and reduce weather helm:

Remove mast rake (or even rake slightly forward).

Reduce wind pressure on the main, or increase the pressure on the head sail. This can be done by shaping (trimming) the sails, and dropping the main to leeward. As the wind increases, shape/position become more critical (should be flatter). If you can, tighten the backstay. This helps to pull the fullness out of the main and will flatten the head sail. The idea is to flatten the sails and keep the draft forward.

Tighten the outhaul to flatten the bottom part of the main. At the same time tighten the Main and Genoa halyard to keep the draft(s) forward. Bottom batten should line up with boom, top batten with masthead. Twist at the top of the mainsail will allow wind to spill.

Move the Genoa lead aft to flatten the lower section and twist off the leech.

Dropping the boom to leeward after shaping will reduce weather helm.

Add a boom vang (helps maintain shape when easing out).

More weight aft and windward, less weight in the bow (move anchor, empty the water tank in bow)

Reef (the main more than the jib).

[Viking Sailor]

Other ways to reduce weather helm include:

1) Have main recut to a battenless and hollow leech shape.

2) Add a fixed outboard keel extension to the stern.

[AVSkipper]

Thanks for the great information. My first charter was last September and our local SoCal weather threw a few twists at me. The wind was about 10 knots when I departed and blew up to about 22 knots. I was not familiar with the reefing lines on the mainsail of this particular Catalina 30 and I wasn't excited about having crew up on the foredeck with the boat heeling quite a bit, the wind, and some moderate swell. My crew was one able bodied, knowledgable sailor and a newbie with a hangover.

The experienced sailor suggested rolling the jib in about 20% and I agreed. He did that and it solved our weather helm problem. My redicence at having crew on the foredeck under the circumstances is an indication that the decision to reef was made a little late. Still, our weather helm was corrected and it was a valuable learning experience, but aren't they all?