April 16, 2014

The chain or rope question

ONE OF THOSE QUESTIONS that never seems to be answered satisfactorily is whether you need rope or chain for your anchor line.  That’s because it all depends. It depends on the kind of boat you have and where you plan to go with it.

I always classify would-be anchorers into two groups: those who anchor frequently overnight on coastal or lake passages, and those who are busy sailing around the world.

For coastal or lake cruisers I’d advise an anchor rode consisting of a section of chain as long as the boat, connected to a main anchor line of a few hundred feet of three-strand nylon.  For world cruisers, I’d advise an all-chain rode. Both rodes need chain right next to the anchor because it won’t be scuffed or cut by dragging along the sea bed as the boat ranges around in wind shifts.

The interesting thing about nylon is how much it can stretch without losing too much strength. This elasticity is a great help when the anchorage gets choppy, and your boat starts to snatch at its cable when the bows rise to waves. As the nylon stretches, it takes the jerk out of the sudden snatch, and then gently eases back to its normal length.  It can do this over and over again without getting tired.

Galvanized steel chain also can prevent your cleats from being jerked out by the sudden strains. It does so by forming itself into a downward curve.  It’s the weight of the chain that forms the curve, and as the boat lurches backward with a wave, it pulls against the weight in an attempt to stretch the chain bar-taut. It’s very difficult to make a heavy chain that taut, and the closer it gets to that stage the harder it becomes, so there is a sort of progressive braking until the maximum strain has passed, after which the weight of the chain will form it into a catenary again, ready to absorb the force of the next wave.

In shallow water there might not be sufficient depth for a reasonable catenary to form, in which case it’s advisable to attach a suitable length of nylon line to the anchor chain, forward of the bow, and take up the strain on that.

In deeper water and very high winds, you can help prevent jerking on an all-chain anchor cable by sending a heavy weight out forward to help form a deeper curve.

Nylon is lighter than chain, length for length, and this might be a deciding factor for racing boats, although chain usually is able to stow itself in a much smaller and tidier package.  But I regard all-chain as essential for round-the-worlders because they so often have to anchor near coral, which would saw through a nylon rode in no time.

There are also times in crowded anchorages when dull-headed operators of dinghies with outboard motors frequently cut too close across your bows, unaware of how close their propellers come to your anchor line. It’s very nice then to know that you have a chain rode. If they make contact, it’s their propellers that will suffer. Serves them right.

Today’s Thought
In the stormy night it is well that anchors twain be let down from the swift ship.
— Pindar, Olympian Odes

Income tax is the fine you pay for reckless thriving.

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

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