Believe it or not, long-distance cruising by sailboat takes a lot of electrical energy. At least on our boat it does. By today’s standards, we have most of the electronic systems that you could find on a cruising sailboat, including radar, chartplotter, GPS, AIS, autopilot, wind/depth/speed instruments and VHF radio. We also have a few extra goodies such as our SSB, stereo, laptop computer, refrigerator and water pressure system. Add in the bilge pumps, lighting and a few other odds and ends, and we have a fairly high demand for 12VDC electricity.

As far as battery capacity is concerned, we like to spend as much time as possible anchored and away from marinas, which means we don’t get to ‘plug in’ for days at a time. To make this possible, we upgraded the factory DC system to give us more capacity and greater charging capability while running our engine. The downside is added weight, but we feel this compromise is OK. On long trips where we expect to be away from marinas and spending more than three consecutive days at anchor, we carry a Honda EU2000 generator in our starboard locker. These generators are quite popular with cruisers in the south and we found ours to be a valuable asset. It is easy to use and generates enough AC power to charge our house bank from 75% to 100% in less than 2 hours. This generator is fairly quiet, but we try to avoid using it in crowded anchorages. However, I am not reluctant to use it when neighbouring boats have wind generators whirring away endlessly.

A drawing of our 12DC system is in this file. Here are the details:

• The house battery bank consists of four 6-volt Lifeline AGM batteries (Type 4C). Total battery capacity is 440Ah, which is enough to keep the fridge running for a couple of days in hot weather. Originally, Strathspey was delivered with two house batteries and an engine starter battery strapped to a battery bed behind the saildrive, under the aft bunk. It’s a tight fit, and not much ventilation. After measuring, I discovered that the four 6-volt batteries would occupy almost exactly the same space, so I displaced the starter battery (a problem to be solved later), built a new battery bed and dropped in the new batteries.
• The engine starter battery is another Lifeline, but designed for cranking. It’s a model T3100 and I had to get it on special order from Polytek in Montreal. I found a space for it under the aft bunk, behind the holding tank. A perfect spot, but requiring longer cables.
• We’re on our third alternator - a 125A Hamilton Ferris. I think it’s the largest alternator you can get to work with a single 1/2″ belt. This brute replaces a 75A Balmar (model 912) that worked like a charm, but was under-sized for the new house bank. The Balmar replaced the OEM Yanmar 55A alternator that came with the boat. When I installed the Balmar alternator, I also installed a Balmar MC-612 digital regulator. This system could be programmed for AGM batteries and we didn’t experience any problems with either the AGMs or the charging system. The MC-612 works with the new Hamilton Ferris as well.
• I did a lot of re-wiring on Strathspey, as you might see in the schematics. The objective was to have two separate battery banks that could be combined for charging and emergency starting. Both the alternator and the shore-power charger feed the house bank, which passes current to the engine bank through a Xantrex Pathmaker battery combiner. Temperature sensors on the house bank and the alternator case protect the system from overheating.
• Strathspey has a Freedom 20 charger/inverter, which provides 100DCA charging capacity and 2000 Watts of AC for whatever you can use it for. We have a few small appliances that require AC. We upgraded the battery monitor to a Link 2000, which allows us to monitor energy consumption more closely.
• I spent a lot of time evaluating alternate energy sources, like wind generators, solar panels and portable generators. In the end, I decided to go with a Honda EU2000i despite the obvious limitation of being dependent on gasoline. I’ve got nothing against wind and solar, but neither of those approaches will generate hot water when we need it.