December 9, 2012

A salt and battery

 AN OLD SALT IN FLORIDA says he wants to go cruising in The Keys with his 20-foot daysailer, which he had used so far only as a round-the-buoys racer. “I want to add a tiller autopilot,” he says, “and of course that will mean putting a battery somewhere. Where, do you think?”

Well, on a small boat like yours a battery weighing 50 pounds or more is probably best amidships where it won’t put the boat down by the bow or the stern. But batteries are always a problem to place on a boat. The trouble is, they need to kept as low as possible to maintain stability, but they also need to be kept as high as possible to avoid bilge water and engine heat (if you have an inboard) and to be accessible.

Batteries need some babying, too. They need to be protected from extreme cold, salt spray, and hot sunshine. They need to be in an area that is well ventilated so if any explosive hydrogen gas is generated during charging, it will dissipate quickly.

Because batteries like to make sparks, they should be kept well away from areas where cooking gas or gasoline fumes can collect. And, naturally, you must be able to fasten them securely so they don’t shift when your boat heels or (gawd’elpus) turns turtle.  They must also be kept in a container that is proof against acid spills, otherwise you might find unwanted holes in your hull.

A battery used to start an engine is another problem. Because of the high current draw of the starter motor, the feed cable should be short and fat. In other words, the battery should be as close to the starter motor as possible.

It should also be as close as possible to its charging source, so that constant small charges from solar panels, for instance, don’t get absorbed as heat in long runs of thin wiring.

On top of all the other requirements, a battery needs to be available for easy inspection, testing, and (if needed) topping up with distilled water. As you will have gathered, it’s impossible to fulfill each and every one of these requirements, so you have to fall back on the age-old sailors’ solution:  compromise and common sense. I wish you good luck.

Today’s Thought
You shall have joy, or you shall have power, said God; you shall not have both.
— Emerson, Journals

Two oldtimers met in the yacht club bar.
“Saw a school friend of yours the other day,” remarked one. “Asked to be remembered.”
“Who was it?” asked the other.
“Can’t recall his name. Doddery feller, grey hair and long beard.”
“He’s an imposter! I never went to school with anyone with grey hair and a beard.”

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

1 comment:

Anonymous said...

Of course you could just use AGM batteries and put them anywhere in any orientation....