August 28, 2011

Kinds of chain

OLD WOTSISNAME was thanking his lucky stars that his boat is on the west coast, and not in the path of Hurricane Irene, when we got around to talking about all-chain anchor rodes.
“I get confused,” he said. “What’s the best kind of anchor chain?”

Well, he’s not the only one who’s confused. An all-chain rode is very comforting when you’re at anchor in a strong blow, and it has so many advantages over a rope rode that most long-distance cruisers use nothing but chain. Anchor line gets dragged across the sea floor a lot. Chain is resistant to chafe on rocks and coral, and chain can’t be cut by the propellers of those idiots in outboard dinghies who pass too close to your bow in the middle of the night.

There are basically three types of chain, proof-coil, BBB, and high-test.

Proof-coil is made of low-carbon steel and has relatively long links. Its breaking strength is between three and four times its working load limit.

BBB chain is made of the same stuff, but has shorter links. It fits better in windlasses and stows more neatly. It has the same breaking strength as proof coil.

High-test chain is stronger than the first two types. It has a higher carbon content, which makes it more prone to rust. Whereas the first two kinds of chain will stretch and deform before they break, the more brittle high-test is more likely to part without warning when its limits are reached.

All three types are sold with a coating of zinc, of course, which should keep rust at bay for a good few years.

Today’s Thought
A subtle chain of countless rings
The next unto the farthest brings;
The eye reads omens where it goes,
And speaks all languages the rose;
And, striving to be Man, the worm
Mounts through all the spires of form.
--Emerson, May-Day

“I see poor old Flossie is getting divorced.”
Yeah, she was the victim of an air disaster.”
“An air disaster?”
“Yeah — last time her husband went to San Francisco he came back by plane instead of by train.”

(Drop by Monday, Wednesday, Friday, for more Mainly about Boats.)

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