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

Tailpiece

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.

Tension in the rigging

OLD WOTSISNAME, who never believes anything I say, just can't accept the fact that when he's sailing that concrete barge of his, the mast is pushing downward with a force of about 13 tons.

"If that was true, the mast would push the bottom out of the boat," he said.

Well, it IS true, whether OW believes it or not.  Few sailors realize it, but the compression load that the mast step must withstand is generally between 1.5 and 2.5 times the displacement weight of the boat.

That's the word straight from the mouth of an expert. David Potter ran Kemp Masts Ltd., in England, one of the largest spar manufacturers in the world, and in his book, The Care of Alloy Spars and Rigging (Granada Publishing) he offers several other tips that OW probably won't agree with.

Among them is the recommendation that you set up your upper shrouds and backstay with a tension of 10 percent of the boat's displacement.  Most people I've talked to say this is too much, but it's the rule I've always followed and I've never had any trouble on that score. It means that your forestay will automatically be given a higher tension than the backstay because the forestay makes a narrower angle with the mast, but that's exactly what you want, to keep your jib luff nice and straight.

On OW's boat, which probably displaces 15,000 pounds or so, he'd need to pre-load his upper shrouds and backstay with a tension of 1,500 pounds, something he can't bring himself to do, even if he managed to borrow someone's Loos tension gauges.

"At that rate, and under constant tension, day and night, the chainplates would probably pull out," he claims.  "Either that, or the bow would rise up to meet the stern."

Well, there are believers and unbelievers in the world of yachting, and OW is a confirmed atheist when it comes to rigging.  But I think he may have to learn to say some prayers nicely when he next gets caught out in a decent blow.

Today's Thought

Ignorance is preferable to error; and he is less remote from truth who believes nothing than he who believes what is wrong.
— Thomas Jefferson, Writings

Tailpiece

The last time they had trouble with the head on the Royal Yacht, Prince Phillip called in a plumber. "Before you begin," said the prince, "I'd like to acquaint you with the cause of the trouble."
"I'm very pleased to meet you, Ma'am," said the plumber, bowing to the Queen.

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

Taming the mast

THERE HAVE BEEN TIMES when the behavior of my boat’s mast has puzzled and even alarmed me. While lying quietly in a sheltered marina slip, with a gentle breeze from abeam, my mast has started to shake back and forth, as if the shrouds and stays had all completely abdicated their dedicated duty.

It took me quite a while to learn that any mast may vibrate in winds of moderate speeds (5 to 14 miles an hour), and the vibrations may become severe when the natural frequency of the mast coincides with the frequency of vibration.

Alternate sideways movement occurs when wind eddies shed from one side then the other. In theory, it’s possible for the mast to vibrate back and forth in any direction perpendicular to the wind direction. Almost always, however, the movement is fore-and-aft, with the wind coming from abeam, or nearly so.

Here are ways to cure, or at least lessen, vibration:

1. First tighten the stays; then tighten the shrouds if necessary.

2. Add a wire or rod inner forestay.

3. For mast with luff-grooves, hoist a stiff narrow strip of heavy sailcloth in the groove to separate wind eddies. The strip needs to be at least 4 inches wide.

4. Turn the boat so the wind is striking the bare mast less from the side, and more from fore or aft.

5. For temporary relief on smaller boats, lead a non-stretch line from a strong point forward, such as a Samson post or an anchor cleat, clove-hitch it securely around the mast as high as you can reach, take it to a winch aft, and tighten as much as you can.

Today’s Thought
The way of the Wind is a strange, wild way.
— Ingram Crockett, The Wind

Boaters’ Rules of Thumb, #198
If you boat has the kind of stern gland that drips water to lubricate the packing, the rule of thumb is to err on the side of too many drips rather than too few. The water flow is needed not only to lubricate the gland, but also to prevent an excessive build-up of heat. About one of two drops a minute is about right when the shaft is not turning. When you’re under power, the rate will naturally be somewhat greater. A flow of water containing oxygen is also needed to protect a stainless-steel propeller shaft from pitting corrosion in the stern gland.

Tailpiece
“Tell me, Vicar, do you believe in sex before marriage?”
“Not if it delays the ceremony.”

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

It’s for good uck

I ONCE ASKED my wife what kind of coin we should place under the mast of an old sailboat we were refitting. “Don’t ask me,” she said, “I don’t believe in it.”

She maintains that placing coins under masts perpetuates a despicable ancient tradition of payola and subservience to petty tyrants—the gods of the wind and sea. She accuses me of being hopelessly superstitious.

Superstitious? Hah! Not me. At least, not compared with some. I once knew a sailor so superstitious that he wouldn’t even pronounce a four-letter word ending in “uck.” In a Rotary Club speech about his ocean crossings, Dr. Earle Reynolds listed the essential requirements for safe passages as: 1. A well-found ship; 2. A good crew; 3. Adequate preparation and maintenance; 4. Seamanship; 5. the Fifth Essential.

He never disclosed what the fifth essential was. He just gave examples of how, er, fortunate some famous round-the-worlders had been. Harry Pidgeon, for example, fell asleep and grounded his boat on the only soft sandy beach in miles of rock-strewn shoreline. Joshua Slocum escaped from pirates when their mast fell down in a squall. And so on.

The smarter Rotarians soon figured out that the fifth essential was the “uck” word, which you never say out loud for fear it will desert you.

Quite right. That’s why, despite scoffing from the vice-admiral, we always have a coin under our mast. It’s for good uck. And so far, knock on wood, we’ve been very ucky.

Today’s Thought
We must believe in luck. For how else can we explain the success of those we don’t like?
—Jean Cocteau

Tailpiece
“Don’t you think George dresses nattily?”
“Natalie who?”