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Power for Windless

1143 Views 3 Replies 4 Participants Last post by MikeOReilly, Jul 10, 2014

Maine_bill

Discussion Starter · Jul 9, 2014

On our 1981 Pearson 35 we live strictly in a 12volt world. We have two 12 volt batteries .... Not sure of the "size" ....
We draw very few amp hours from the batteries....
We use them to start engines, VHF radio and a few 12 volt cabin lights..
We have no inverters

What will I have to consider (regarding more batteries, alternator etc??) if I want to power an electric capstan that draws, say 30 amps...

What will I need to add to my current system.... Two twelve volt batteries, battery switch (no separate house/starter battery)...that's it....very simple

More batteries,,, bigger alternator...????

Thanks
Bill

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mitiempo

· #2 · Jul 10, 2014

A windlass that draws 30 amps is not large enough for a 35' boat. Figure closer to 70 amps.

I have always felt that running wires suitable for the load from aft to the windlass makes the most sense. A larger battery bank is a plus. The engine will ideally always be running when the windlass is.

Bigger alternator? - depends what size you have now.

Decide on a windlass and the specifics will be easier to figure out.

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chucklesR

· #3 · Jul 10, 2014

You will need to run wire to the windlass (note proper spelling) that is of suitable size to carry the load (probably #2 gauge). Keep in mind that when figuring the length of the line you have to include both to the windlass in back.
Put a suitably sized fuse on the positive side of the wiring within 6-8 inches of the battery.
Seriously, if you don't know what you are doing be safe and get some qualified help. The #1 cause of boat fires is electrical shorts and I suspect they are caused by bad wiring.

If you have room add an extra battery, either way look at the ones you have and figure out what you have, maybe add a monitor so you can determine the condition and state of charge.
Speaking of charging, you likely have the standard original alternator, putting out 35 amps at peak (i.e. somewhat less at idle). Not to worry too much because your windlass usage is in likely in the couple of minute range unless you have to reset several times.

BTW, Mtiempo/Brian up above is likely correct, a windlass drawing 30 amps (360 watt) is not going to be enough for a suitable anchor and rode weight on your 35 foot Pearson, even with a lunch hook of 35 pound anchor, 10 feet of chain and the rest rope you are looking at at LEAST a 1000w windlass (Maxwell rc8 for example).

Even at 1000w pulling your anchor up for 2-3 solid minutes won't kill your batteries - assuming you are motoring for a bit to get sailing room.
Here's a good 'how to choose' link - Choosing a Windlass - Lewmar

You can maybe get by with an underpowered windlass, but only if you are willing to run below decks and reset the breaker several times when it trips. Not fun.

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MikeOReilly

· #4 · Jul 10, 2014

Maine_bill said:
More batteries,,, bigger alternator...????

This is probably not a useful answer, but have you considered a manual windlass? I've had one for years on a bigger boat that yours. Works great. In the years we've had our Plath bronze windlass the only problem I've had was breaking the handle (metal fatigue). Easy to fashion a new one.

Yes, there are downsides to a manual, but balanced against the challenges of an electric (which I'm not philosophically opposed to), I'd suggest you at least seriously consider it as an option. Seatigers are fairly easy to find in the used market.

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