LIfe aboard a one-fuel boat

 Katy and I have been living aboard Idril, our Garcia Exploration 45 sailboat, for about 6 months now. Our boat is unusual for a sailboat in that the only fuel we carry is the diesel oil for our propulsion engine.

 

Idril at night

Most boats also carry propane, butane or alcohol for cooking, and many also carry gasoline for the outboard motor on their tender. Idril, though, has an induction cooktop and combined microwave/convection oven for cooking, and an electric outboard for the tender.

Jerry at the induction cooktop, with the immersion
blender close a hand. Lots of gadgets!

 

This means that we need a lot of electrical power, which we have to both generate and store. 

Storage is handled by 4 distinct battery banks:

• Primary storage is a bank of 4 24-volt lithium iron phosphate (LiFePO4) batteries from Victron, with a capacity of about 20KW hours.
  
  
• Secondary storage is three separate banks of more conventional lead acid batteries:
• a pair of 12V, deep discharge batteries for all the 12V equipment on board: lighting, navigation and radio systems, fans, refrigerator and freezer, pumps, etc.
• a single 12V starter battery for starting the diesel engine
• a 24V bank composed of 4 12V starter batteries near the front of the boat to drive the windlass, capstan and bow thruster

The primary 48V bank charges the other three banks through a set of DC-to-DC chargers. 

A wonderful side effect of this arrangement is that each type of battery is used in the manner best suited to its particular chemistry:

• The lead acid batteries are kept essentially fully charged at all times, which is how they last the longest.
• The lithium batteries are rarely fully charged, generally fluctuating between 60% and 95% charged. This is how they last the longest.
  

Power generation comes from three sources:

• A 1KW array of solar panels, mounted on the arch at the stern of the boat.
• A conventional alternator on the diesel engine
• A special, high-output AC generator, also mounted on the propulsion engine, and controlled by a smart system controller called Integrel.

The Integrel controller comes into play any time we are running our diesel propulsion engine, such as departing from or arriving at an anchorage, mooring or dock, or motoring due to lack of favorable winds. It is capable of adjusting the amount of power produced by the AC generator, and therefore the load placed by the generator on the engine. When the engine is running at low speeds, the generator produces a lot of power; as we advance the throttle, the generator backs off, allowing more of the engine's power to go to the propeller.

the Integrel system monitor

 By having the Integrel generator on the propulsion engine, we are able to do without the completely separate auxiliary generator common on large sailboats, saving space and complexity. 

The final piece of the system is a 5KW inverter that produces 220VAC power for appliances (the induction stove, microwave oven, hot water kettle, water maker, electric toothbrushes, etc.) from the power stored in the 48V lithium batteries.

Until we started cruising, we were a bit anxious as to whether the system would work out as well as intended in the real world. The past months of cruising have confirmed our expectations: the system works beautifully. 

During the summer and early fall, the solar panels produced a lot of power even on overcast days, and on sunny days could easily keep up with our daily consumption. Now that we're into winter, of course, not so much. 

The Integrel generator produces power as we motor for the usual reasons, and we have only rarely had to run the engine specifically for the purpose of recharging the batteries. For short stays in a marina, we don't even bother connecting to shore power; we just don't need it. 

We wanted our boat to be highly independent from shore and comfortable enough that we can live aboard it indefinitely and not feel entirely like we are camping out. So far, we seem to have succeeded.