August 23, 2011
The missing link
SOMETIMES I WONDER if there’s a small part missing from my brain. It’s the part that deals with heeling in a sailboat. Specifically, it’s the part that can understand why a boat with a low, spread-out sailplan should heel less than a boat with a tall, narrow sailplan.
I have read innumerable times that a gaff-rigged ketch with a bowsprit will heel much less in a wind of a certain velocity than will a high-aspect-ratio sloop. And for the life of me I can’t see why.
Now let me say straight away that I understand the extra leverage gained by a long tall mast of a sloop, compared with the stumpy masts of a gaff-rigged ketch. I accept, too, although with some cynicism and doubt, that the wind at the top of a mast blows harder than the wind at the bottom.
However, there can be no gainsaying the fact that it takes a certain amount of energy to move the mass of a sailboat through the water. That energy comes from the wind, and if the wind is abeam, or forward of the beam, it tends to make the boat heel to leeward.
Surely it takes the same amount of energy to make similar hulls heel over to the same number of degrees, no matter whether the sails are high or low, doesn’t it?
Obviously, the higher the center of effort, the less sail area is required to make the hull heel over. In the gaff-rigger, more sail area will be required to achieve the same amount of heel because the center of effort is lower, and the sails don’t have as much leverage.
In other words, the sails of the sloop are more efficient since they create the required amount of heeling energy with less sail area.
Thus, to say a low-lying rig will produce the same amount of energy (which translates to the same sailing speed) with a lesser amount of heel is nonsense. If the gaff rig doesn’t produce as much heel, it also lacks the ability to create energy to move the boat forward. In other words it lacks sail area. And that is surely not something to crow about as if it were the best thing since sliced bread. Whether your sail is tall and thin, or low and wide, it needs to produce the same amount of heeling energy.
If you were to take this questionable theory to its limit, a boat with sails a foot high and 100 feet long would cause no heeling at all. And very little forward motion.
Once a canard like this starts making the rounds, it gets repeated thoughtlessly by a thousand copycats eager to show off their new knowledge, and soon enough it becomes part of the accepted lore of the sea.
I really wish I, too, could accept it. I don’t like to stand out from the mob and be jeered at. But my sadly incomplete brain won’t let me. You won’t believe how I suffer.
The flying rumours gather’d as they rolled,
Scarce any tale was sooner heard than told;
And all who told it added something new,
And all who heard it made enlargements too.
—Pope, The Temple of Fame.
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