May 30, 2013

Heavy vs Light Displacement

THERE HAS NEVER BEEN any general agreement on whether heavy-displacement sailboats are more seaworthy than light-displacement boats. It’s a subject that occupies many hours of beer-drinking time in yacht-club pubs and all too often results in harsh words and broken friendships.

Perhaps the views of K. Adlard Coles will be helpful in this respect. Coles was one of the world’s best-known long-distance racers and cruisers. He was a British publisher and one of a small band of fearless ocean racers who roamed the high seas in tiny boats just after World War II. He was unique in that he kept details of all the storms he nursed his little vessels through.

In his magnum opus, Heavy Weather Sailing, Coles agrees that the extreme shape of the modern ocean racer’s hull, which is designed to reduce drag from the underwater surface with its cut-away fin keel and spade rudder, makes a boat fast and efficient.

But, he points out, the sail area for such boats is critical and must be “exactly right” in relation to the strength of the wind, both to preserve balance and to avoid the rudder’s stalling in the event of excessive heeling or a knock-down in a squall.

 Coles feels that the motion in fin-keelers is much livelier than it is in older-style boats (no arguments from anyone about that) and thus steering a fin-keeler requires greater concentration, so even when you’re cruising, you can’t leave the helm alone for a moment.

He says steering is at its worse when the boat is running in strong winds, particularly with the wind on the quarter. Such a boat needs a constant supply of well-rested crew at the helm. But its livelier motion will put the crew under greater strain than a “conventional” boat would, and it would likely provoke more seasickness among the crew.

In exceptionally rough going, another disadvantage shows its face. The spade rudder is much more vulnerable to being damaged, whether it is attached to a skeg or not.

It’s interesting to note how enthusiastic a fan of light-displacement boats Cole used to be, and how successful he was in campaigning with them.  But, significantly, he was later converted to heavier-displacement ocean racing boats of the same length. He found these to be better sea boats with “immeasurably improved windward performance in really heavy weather” because of their ability to carry more sail and provide more drive.

Today’s Thought
He who will not be ruled by the rudder, must be ruled by the rock.
— Isaac D’Israeli, Curiosities of Literature

“Frank, please lend me $50.”
“No can do, Charlie. Here’s $25.”
“But I asked for $50.”
“Yeah, I know, Charlie. But this way you lose $25 and I lose $25.”

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

No comments: