Weather Helm

Keiron… you told me Nirvana has heavy weather helm.  I do not experience this on Santana.  Have you tried easing off the main sail as much as you can without the main’s luff lifting?If you still have heavy weather helm with that, I wonder about the sails.  How did you come by them?  Are they to the original specification?  The foresail should be a genoa whose clew should reach down to the top rail near the shrouds.  If the fore sail were smaller this would give you the weather helm you experience.

Tony

One thought on “Weather Helm

  1. Boudewijn Post author

    Hi Tony,
    must confess I find my MG30 subject to weatherhelm, especially going upwind in “windy weather”. From Beaufort 4 already. So I am talking jib rather than genoa. Also with the original North Sail sails. (Too much) weatherhelm is not good, because the required rudderangle is a drag on the boatspeed.

    Not surprisingly, because the MG30’s stability comes from ballast rather than shape. Hence much heeling at modest winds. Hence the keel resistance pulling say 0.5 m to luff of the centreline and the forward sail force component pushing 3 m to lee of the CL. Let us say a 1000 N (200 poundforce you might want to call it) each. This indeed results in weatherhelm, because the rudder has too make good on this.

    This weatherhelm is easily remedied by reefing the main, to keep normal helmforces. Check the GPS before and after reefing and you will see that speed and especially vmg usually benefit. And if the wind blows up abit more you are at least not at full sail anymore. Though reefing at force 4 seems a bit early.

    “Modern” boats (less ballast and more form stability than an MG30) have more INITIAL stability. Hence less INITIAL weather helm. Catamarans are the ultimate in this modernity. No INITIAL weatherhelm at all, the lee floater and its resistance are even underneath the sailforce, rather than our keel lateral point pulling (3 m?) to the lee of our sail lateral point pushing.
    Uuuuh…., until the cat heels just a bit too much (let me call this then the ULTIMATE “stability”) and overturns of course. Thats why they usually have an (inflatable) skippyball in the masthead.

    mvg Boudewijn

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