Thursday, August 30, 2007

Dumb Question

The following question arrived by email today with the subject Dumb Question..

If you have a large sailboat that has battery powered equipment, and you keep it on a mooring out in the water, how does your battery stayed charged? Is the only way to re-charge the battery is to keep the boat on a dock with power? Thanks.

First of all there are no dumb questions. There is so much to know about sailing that all of us have gaps in our knowledge. In fact there are so many different types of sailboat and ways of going sailing that most of us have huge gaps in our knowledge. For example I know quite a lot about small single-handed racing dinghies and racing strategy, tactics and rules... but next to nothing about ocean cruising or navigation or how to maintain the equipment on a large yacht.

Which makes me wonder why this question was addressed to me. But I think I know the answer: large sailboats keep their batteries charged when on the moorings with wind generators or solar panels. I've often seen the generators spinning away when I've been ducking and weaving in my Laser through mooring fields.


And on the subject of dumb questions I just came across this quote in the signature of a regular contributor to Sailing Anarchy, the incomparable Gouvernail...

Sailors who are fascinated by the volume of what they don't understand and who are eager to announce their ignorance tend to have a realistic assessment of their knowledge, a solid grasp of what they claim to understand, and are the very best sources of information.

Sailors who act like they know everything are idiots and should be avoided.

Do any of my readers who actually have some experience with charging yacht batteries want to add anything for my friend with the not-so-dumb question?

12 comments:

Litoralis said...

I don't know anything about it, but I do know that one of my friends from the MIT sailing team has a company called Genasun that makes "advanced energy products for sailboats and alternative energy applications." His name is Alex MeVay and he also sails Mini class boats.

Anonymous said...

from Steve Hendry in Baltimore

Main advice would be to obtain a copy of Nigel Calder's book on boat electrical & mechanical systems (third edition is the current one). Every owner of a boat big enough to raise that type of question should have a copy (I have two, one at home and one aboard).

J.P. Clowes said...

Your questioner didn't say if he had an inboard or outboard engine. If it is an inboard, I can offer this. My Parents old C&C 29 had an inboard engine with an alternator that recharged the batteries (it had 2) whenever it ran, much like your car does. We didn't have another source of power, and never had a problem. We kept it on a mooring, and didn't even have a shore power plug. If we were doing something that required power, without the engine running, we were sure to only run one of the batteries down. We then started the engine with the main power switch on "both" to get juice from both batteries and recharge both when the engine started again. We were also kind of old fashioned, and didn't have a microwave, refrigerator, or any of the other modern conveniences many boats have now, so, that cut our power draw too. (Alcohol stove/oven and Ice Box were just fine with us.)

Litoralis said...

So, if you have a boat with an engine (and you don't mind running it to charge batteries), do you still need some kind of wind or solar powered charger/generator to keep the battery that starts the engine topped up?

Anonymous said...

Steve in Baltimore again

Not necessarily. My previous boat had only engine charging (no shore power connection). It's important to have the starting battery isolated, f'rintance by the voltage sensing relay battery combiners available at West Marine.

Christy ~ Central Air said...

My Capri 18's outboard motor doesn't have an alternator to charge the battery, so I use a rigid solar panel that I bought on sale at Harbor Freight for $30. As an added layer of weather protection, I sealed all the seams and edges with silicone caulk, and I switched out the jumper-cable-type connectors on the panel to a 12v lighter plug that I bought at Radio Shack. This allows me to simply plug it into my 12v receptable on the boat. When I'm sailing, the panel is out of the way on the quarterberth. While docked, it's on the cockpit seat. It keeps my battery nicely charged and was very simple and inexpensive to "install."

turinas said...

I love the quote from Gouvernail. It's one of the many reasons why I sail. You never stop learning. And what I dont know about sailing could fill the Library of Congress

Anonymous said...

I have a 5 hp mercury outboard with an alternator that works beautifully, and then also use a solar panel to trickle charge

Zen said...

trickle charging at the dock or mooring with solar or wind power, covers it... or a hamster in a cage hooked up to your battery.

Carol Anne said...

If you're not leaving the boat alone on its mooring for more than a couple of weeks, you may not need any other power source -- assuming your batteries are in reasonably good condition.

During the summer, our boats are in a marina that doesn't have electricity, and Pat and I have discovered that a very simple solar panel (the one we got was designed for use with an RV, and as far as I can tell, it's identical to the ones in the marine stores, but the price tag was much lower) keeps the battery in our cruising boat nicely charged.

JP said...

Gouvernail is spot on. There shouldn't be any shame in asking questions if even Ellen Macarthur says she's still learning new things.

Thats one problem I have with sites like sailing anarchy which have members that IMHO jump too quickly on the perceived failings of others.

Fred said...

If you like the constant noise and vibrations, put such a thing on your boat. Otherwise go for solar power.

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