July 14, 2016

Beware deck-stepped masts

IT PAYS SAILBOAT BUYERS to be suspicious about deck-stepped masts. It pays to check if the deck directly beneath the mast has sagged. And the way the canny buyer does this is by feeling the tension in the mast shrouds. A soft deck simply won’t support much tension. It will just sag further.

You can just about play a tune on a properly tensioned shroud. In fact, I’m always amazed at how much tension the experts advise you to wind in via the turnbuckles.

I have in front of me the carefully preserved pamphlet that came with a pair of Loos tension gauges I bought many years ago, and it says:

“Contrary to popular thought, a slack rig is more punishing on a hull than a properly adjusted tight rig. Insufficient tension will not reduce the loads transmitted to the hull. Slack rigging will punish the spar and rigging needlessly by allowing excessive movement, chafe, and shock loading.”

Now for a boat with 7/32-inch 1 x 19 stainless-steel shrouds, such as a 27-foot Cape Dory I once owned, the Loos people advise you to pre-load the tension to 700 pounds. The forestay should be tightened to 1,000 pounds.

I was always scared to do this. The numbers sounded too big. When I first bought my gauges I screwed up my nerve and set the shrouds at 450 pounds apiece. Years later, encouraged by the fact that the sides of the boat had not yet risen to meet each other, and the mast had not yet been driven through the deck, I raised the tension to 600 pounds. But I never got as far as 700 pounds.

The Loos pamphlet goes on to warn that “the lateral stiffness of the mast and the fore-and-aft stiffness of the spreaders is reduced by a factor of 2 when the leeward shrouds go slack. This important structural characteristic is not generally recognized.”

I presume that when they say “reduced by a factor of 2” they mean the mast stiffness is halved. That sounds quite serious. But then, one must also recognize that they are in the business of selling tension gauges. Not that I would suspect them for one moment of deliberately scaring people into buying their gauges. It’s just that I’m a born skeptic. And 600 pounds was just fine for me, thanks.

Today’s Thought
We're probably the opposite of the Osbournes. We run a very tight ship.
Hulk HoganH — Hulk Hogan

Last month a local Small Claims Court judge told a nervous woman witness to make herself at ease, and talk to him as if she were talking to her husband or friends at home.
The case is still proceeding.

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