Both Wind Horse and the FPB 64 Avatar share the same systems logic when it comes to AC and DC power. They are engineered to minimize genset time, running mainly on traction batteries at anchor with power supplied by a pair of 150 amp/28VDC alternators under way. On Wind Horse we have just 550 hours of genset time since launching in 2005, 100 of which came during sea trials when we were breaking in the little diesel and another 50 in Alaska when we were heating the boat with the reverse cycle air. That leaves 400 hours over five cruising seasons.

How have we managed this?

To begin with, we use a huge amount of power by our sailing standards. Between cooking electrically (the past year anyway), two computers (one with dual monitors), the usual array of devices charging their batteries, quartz halogen lighting (which we prefer to LEDs and fluorescents), along with two freezers and a fridge, the amp hours are over 300 per day.

In terms of battery capacity we can sit for three to four days. However, our usual routine is to run the genset every other day, during dinner, doing a load of washing and drying while charging the batteries a bit. We may watch a movie or run the air conditioning. The genset run doesn’t come close to recharging the batteries, but it offsets some of the consumption, and covers the drain from washing and cooking the evening meal. Full charging will wait until we are moving the boat and come from the engine mounted alternators.

As high as our consumption appears to us, it is a half to a third of what most large motor yachts consume, which is why their gensets are running so much of the time (they also don’t have the huge traction battery banks and the 9kW alternator based charging system on the engine).

We’ve found that there are several keys to keeping power consumption under control to minimize genset run time at anchor:

• The inverter bank (three 2500 watt Victrons) is turned off when not required saving the idling current. On the FPB 64 there is a dedicated small appliance inverter so the big bank can stay off most of the time (this smaller unit should be turned off at night).
• We put computers to sleep, or turn them off when they are not being used.
• Hot water is generated with the Kabola boiler rather than electric heating elements.
• We don’t worry about lighting, but we do turn it off when we are not using it. Engine room lights, four big fluorescents, have to be turned off (we sometimes forget and they burn all day).
• The wash/dry cycle is done with the genset (with excess genset capacity going into battery charging.
• DC meters on the various electrical panels are left off unless we are monitoring something.
• Electronics such as GPS, wind and depth, etc. are left off unless anchorage conditions warrant otherwise.

You could argue that the effort required of us with this power management could easily be offset with an extra hour a day of genset time (roughly 100 additional hours in a normal six month cruising season). That’s around three to four liters (one US gallon) of diesel a day. The cost is certainly modest, and even if we doubled the genset hours we’ll be long past the cruising age when the genset needs a rebuild. But we like being efficient, are used to being penurious with diesel fuel, and old habits die hard.