WEATHER
HELM is not much discussed in polite sailing circles. In the same way that you
don’t entertain party guests with tales of an ancestor hanged for treason, or a
maiden aunt gone mad from syphilis, you don’t go around telling everybody your
boat has weather helm, especially if you’re trying to sell it. Nevertheless,
most boats have it, and it can be a vexing thing to have.
Weather
helm is the name we give to the tendency of a sailboat to turn bow-first into
the wind. The term is actually incorrect, since weather helm is what the
helmsman applies in an effort to counteract the tendency to round up, which is
known as griping.
If your
boat has a tiller, your arm can become mighty tired fighting weather helm. It’s
an unrelenting tug that soon becomes much less than fun. Even if you have a
wheel, and don’t have to counteract griping with sheer muscle power, excessive
weather helm is a bad thing because putting the rudder over in an attempt to
keep the boat going straight slows the boat down considerably and puts a heavy
strain on the steering gear. In other words, like a leaky loo, too much weather
helm is not a good thing to have.
So what
causes it, and, more importantly, how do we cure it? Well, you might have to
face the fact that it’s not always possible to cure it entirely, depending on
the shape of your hull, the shape, size and position of your keel, and the
position of your masts and sails.
What the
designer seeks in the first place is a close balance between the center of
effort (CE) of the sails and the center of lateral resistance (CLR) of the keel
and the underwater hull and appendages.
Normally,
the CE is a little forward of the CLR, because (just to make things more
difficult) the CLR moves forward as the boat starts to move through the water.
So it’s partly a guessing game with a new design. You may have seen boats like
the Catalina 30 with little bowsprits added at a later stage. That’s an
after-market effort to move the CE forward, to counteract weather helm. But you
have to be careful. Move it a little too far forward and you get lee helm,
which is even worse than weather helm.
Some
designs will always carry more weather helm than others. Hull types like the
old IOR designs with a lot of beam carried a good way aft, and hard bilges,
will quickly gripe in a puff. Boats with high-aspect-ratio rigs carry weather
helm more quickly because the CE of the tall narrow sails is higher, so CE
moves farther outboard over the water as the boat heels, thus pushing the boat
from the side, and much farther out from the side, gaining leverage with every
degree of heel.
Boats with
blown-out, baggy sails suffer from weather helm because the CE moves aft. You
can cure a bit of that, especially in rising winds, by tightening the halyards
and flattening the sail any way you can, which will move the CE forward. The
deepest bulge in a sail, the camber, always moves toward the edge under most
strain. You can try that yourself with a handkerchief if you need convincing.
What other
cures are there? Well, you could move the whole mast and rig forward. (Well, most of us couldn’t, actually, for
obvious reasons.) You could rake the mast forward very slightly, or at
least set it completely upright if it’s leaning aft. If you have a racing mast,
a bendy mast, hauling on the backstay will induce an aft bend in the mast that
will flatten the sail and reduce weather helm. In heavy winds you should set
the mainsail traveler down to leeward as far as possible so that the sail
spills wind and lies flatter. That helps quite a lot.
One thing
often overlooked is that a large headsail can contribute to weather helm, too.
Quite a lot of the area of your 150 percent genoa lies aft of the CLR, which is
somewhere in the middle (in fore-and-aft terms) of your keel. You might as well
be adding that extra genoa area to your mainsail. Change down to a smaller
genoa or working jib, or roll it up to a similar size, and your CE will move
forward.
And let’s
not forget the best cure of all: reef the mainsail. Get rid of the sail area at
the aft end of the boat that is constantly pushing the stern away from the wind
and making the boat want to point up.
A little
weather helm is a good thing. You don’t want it to disappear completely. You
just need to be able to control it. Tank testing has shown that about 2 or 3
degrees of rudder from dead center helps lift a sailboat to windward. More than
4 degrees just acts as a brake to your progress.
In gusty
weather, most of us will try to ride out the puffs by easing the mainsheet and
putting the rudder over to leeward, but because excessive heeling is a major
cause of weather helm it’s always wiser to reef down and keep the boat more
upright if the wind is likely to continue at a greater strength.
Do what
you can to lessen weather helm. It’s a good feeling to be in decent control of
your boat in heavy wind. And I’ll tell you what — I won’t mention your weather
helm to anyone if you don’t mention my maiden aunt.
Today’s Thought
It would have been as though he were in a
boat of stone with masts of steel, sails of lead, ropes of iron, the devil at
the helm, the wrath of God for a breeze, and hell for his destination.
—Emory A.
Stones
Tailpiece
“The doctor said I’d be on my feet in two
weeks.”
“Was he right?”
“Yeah, I had to sell my car yesterday.”
(Drop by every Monday, Wednesday,
Friday for a new Mainly about Boats column.)
6 comments:
Many years ago I did a trip from NZ to the Pacific Islands in a non extreme traditonal cruising yacht. She had diabolical weather helm when she was hard pressed. When this happened it was reasonably cured by putting 6 rolls in the mains'l (moving the centre of effort forward). A local designer suggested that the trouble was the great bouyancy in her forward quarters which when immersed produced a huge force compelling the hull to round up into the wind - with the result that a lot of helm had to be applied to stop this happening - apart from the helm she was a lovely commodious cruising boat - and we had a wonderful trip.
Sorry John,
Emery A. Storrs quote:
http://www.worldofquotes.com/author/Emery+Alexander+Storrs/1/index.html
-TC
TC and Kelly:
Yes, of course it was Emory A. Storrs. Thanks for putting me straight. Sorry for the finger trouble.
Cheers,
John V.
I know you're writing English but I'm going to copy this and post it somewhere for the future. The day I can reread it and easily follow what you've said I will consider I have learned something about sailing. Until that day ....
Sorry if you're confused, Mike, but I try to cater for sailors of all kinds in these columns, and I guess some of you get lost from time to time. My advice would be to learn all you can meanwhile about the centers of effort (CE) of the sails, and the center of lateral resistance (CLR) of the hull underbody. They are they keys to weather helm, although not the entire answer, of course. Nothing in sailing is ever the entire answer to anything.
John V.
John, I wasn't complaining. You wrote a good post and I was pointing more to the long road I still have to catch up. I've enjoyed following you so far.
Post a Comment