Wiring Windlasses - SailNet Community
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Wiring Windlasses

I am about to purchase a windlass for my 34-foot sailboat and I'd like to know your recommendations regarding a choice of installations. Should I wire the windlass to the house batteries, which will entail a fairly long run of heavy guage (and expensive) cable; or should I install a battery dedicated to the windlass that is mounted rather close to it, such as under the V-berth?

Sue & Larry respond:
In a 34-foot, aft-cockpit sailboat, your cable run from the house bank forward to an electric windlass could easily equal 25 feet in one direction. If you choose a windlass that is capable of drawing 100 amps from your battery bank, then your cable size should equal No. 2 wire (at a minimum) given an acceptable voltage drop of 10 percent for this application. For even better performance, you'd be smart to opt for even a larger size. If it were our personal boat, we'd choose either 1/0 or 2/0 battery cable.

So, where do you go from here? As you mentioned, you can either mount a battery forward near the windlass, or run 50 feet of heavy cable from your house bank through the lockers & under the floorboards until you finally make it to the bow. Quite a few people recommend mounting a battery forward, and it does seem tempting, but we feel that there are a couple of downsides to this approach. 

Firstly, you need to buy a heavy-duty battery and secure it in a location that provides easy access for maintenance. Then, you have to charge the battery, and here's where we see a potential problem. If your windlass draws 100 amps during operation, the battery can be quite discharged after raising and stowing your anchor. A highly discharged battery is often able to accept the full output current from your alternator. If like many sailors today, you have a high-output alternator on your engine, its output could easily be 100 amps or even more. So, now you need the heavy cables running from your engine to the forward battery just to handle the charging current from your alternator. Voila, you're back to installing the heavy cables anyway, plus you now have a battery mounted forward. 

If your alternator output is paltry, you could get by with smaller wires for charging your windlass battery, but you'll still have to make the run through lockers and under floorboards. 

We've heard of some sailors mounting a dedicated windlass battery forward, and installing a dedicated solar panel on the foredeck to charge just that battery. We're don't believe, however, that this arrangement would allow for
multiple anchoring attempts without fully exhausting your battery, plus it's not cheap either. 

We feel that if you bite the bullet now and install adequately sized tinned cable from your house bank forward to your windlass, you should enjoy many years of easy anchor raising with minimal future maintenance.

Sue & Larry is offline  
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