June 14, 2012

That lopsided feeling

HAVE YOU EVER HAD THE FEELING that your boat sails better on one tack than the other? Does she always point better on port than on starboard?  Or are you just imagining it? Maybe not.  Boats do vary from side to side  because of differences in temperature, humidity, and general exposure to the elements when they’re being built.

This affliction affects even the best and most careful boatbuilders.  One man who used to work for a prestigious California boatbuilder commented: “Sometimes the variance is minimal and sometimes it is quite noticeable. When I worked for Sam Morse building the Lyle Hess-designed BCCs (Bristol Channel Cutters)  it was quite obvious that the hull mold was asymmetrical. One had only to stand behind the boat and look forward along the garboards (where the lower part of the hull joins the keel) to see the difference between the port and starboard side of the boat. I noticed this difference quite readily when installing the ballast. The lead castings for the ballast reflected the hull’s asymmetry.”  

It’s not only hulls that suffer asymmetry, either. Decks are often different from side to side on fiberglass production boats and it’s not unknown for owners to discover that the mast(s) are not exactly centered, or that the rudder head does not come up through the exact center of the cockpit.  It’s because the deck tooling is usually built on the first hull to come from the hull mold. Slight differences in expansion and contraction of all materials involved during the tooling phase are there forever once the molds are laid up on the tooling.

The differences in sailing performance, from tack to tack, are likely to be absolutely minimal, however, and there’s no suggestion that the ordinary asymmetry resulting from normal boatbuilding practice could cause any danger under way.  Nevertheless, if you do consistently get the feeling that she performs better on one tack than the other, or if your helm always pulls one way more than the other, it wouldn’t hurt, next time she’s out of the water, to take a good long look, or even photographs, from ahead and astern, to see if you can spot any substantial differences. Then you can look forward to lots of sleepless nights figuring out what to do about it.

Today’s Thought
Error is a hardy plant; it flourisheth in every soil.
— Martin F. Tupper, Proverbial Philosophy: Of Truth in Things False.

“Doc, is it true that if you don’t drink, smoke, or chase after women, you’ll live longer?”
“Well frankly that’s the theory — but we’ll never know until somebody actually tries it.”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)

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