SARAH AND THE INCLINOMETER

By Dr. Robert E. Plucker

Circa 2000

Those people who are not accustomed to sailboats are often amazed and alarmed when the boat leans over to one side.   This is heeling, and it is a part of being propelled by wind.  One explanation that I have heard is that every other kind of boat will tilt to one side when hit by a wave, and then will tend to tilt to the other side before coming to an equilibrium.  A sailboat heeled over will not do that; it will lean over away from the wind; its motion is dependent on the wind, and to a much lesser extent, on the wave action.  Sailboats larger than tiny day-sailers will have weight below the hull to counterbalance the sideways thrust of the mast and its sails.  This weight, whether a fixed keel or moveable centerboard, can be nearly half the entire weight of the boat, causing it to pop up after you have knocked it down like a child's toy.  Many sailboats are capable of righting themselves automatically even if they were entirely capsized.  The force of heeling has to become less as the boat leans further and further over, spilling the wind out of the top of the sail.

 

Another aspect of boat stability is the shape of the hull.  In general, a flatter bottomed hull will want to stay upright and will tend to sail poorly under extreme heeling.  A more round bottomed boat will heel more under the same strength of wind, but will sail effectively in that condition.  The Newport 30 that we enjoyed so much for sixteen years was rather flat; Greta, the Ericson 34 that we have loved so well for fourteen years is rather rounded.  I bought a cheap little inclinometer, similar to a carpenter's level to check on just how far the boat actually heeled over.  Incidentally, any boat will "list" if it is out of balance; a poorly distributed load is usually the cause.  Sailboats "heel", and their skippers tend to get upset if landlubbers keep insisting that the boat is listing. 

I enjoy taking young people out sailing, and years ago I would take my college students out on Saturday day trips.  With son John in high school, I took many of his friends out.  So on one of these expeditions with John and his high school friends I had two new-comers to sailing aboard, Sarah and Soren.  (No, they are not related to each other at all.)  Soren took to the sailboat motion with little trouble, but Sarah seemed a bit apprehensive.  She caught sight of the inclinometer, mounted right where everyone could see it.  What was that for, she wanted to know.  I told her it was to let me know how many degrees the boat was leaning over from the vertical.

We got out from the shelter of the inner harbor a bit further, and the heeling increased to about fifteen degrees.  As you get further out, in the Haines harbor, you can expect stronger winds.  We got them, and the heeling increased to perhaps twenty degrees, but varying with the small gusts of wind that one usually encounters in this mountainous country.  By the time we got to thirty degrees of heel, Sarah got nervous.  She wanted to know how far the boat would tip to one side before it would refuse to come back upright.  I explained to her approximately what you have read in the first paragraph of this essay.  Since we were now in the middle of Lynn Canal where the wind could be expected to be the strongest, I felt safe in telling her that if she wanted to get really concerned, she could start worrying at about forty degrees. 

Where there are gusts of wind, there are sometimes GUSTS.  Wouldn't you know, within seconds of having said that, one of these GUSTS came along and gave us a real “knockdown.”  I didn't take time to look at the inclinometer, but I know from experience that we heeled a good bit more than forty degrees.  We didn't have just the lee rail under water; we actually took in a few gallons over the coaming of the cockpit.  This is one of the times you listen to the screaming and rather wish you had reefed the sails a while back when you had the chance.  But even these strong gusts are only gusts, and the weighted keel did its job very well indeed, and we popped right back up to our former position.   

But Sarah must have had her eye on the inclinometer, because all four or five of us aboard could see that she was terrified.  Perhaps if I had just stuck to the explanation in the aforementioned first paragraph she would have been less scared, but no, I had to mention forty degrees. 

After this GUST, we did not experience any more, but to reduce chances of more terror, I turned downwind a bit more, slackened the main and the jib a bit, and the wind cooperated by moderating.  This experience was scary for Sarah, but not long after that she begged and pleaded to come along with me and several others to go all the way to Juneau to a Cross Country run.  Lest we forget about Soren, he was cool; I don't think I have ever seen him flustered.

Thanks to Wikipedia for this photo.