Generating electrical power and making fresh water are critical for running a yacht offshore.

We need fresh water for drinking and cooking; for washing – Offbeat has 4 cabin showers and a deck shower by the swimming ladder; and for cleaning – we have a dishwasher, a washing machine and also a deck hose for washing salt off the boat and equipment. We’ve been plagued with red Saharan dust through the Mediterranean!

We make water with a Dessalator Duo 100 litre per hour watermaker that is situated in the starboard engine compartment. This has both 12v and 240v pumps to push the seawater through the membranes (black tubes in the photo) to make fresh water. This consumes a lot of power so we run the watermaker whenever we are running the engines (as we have excess power at this point) or we have to run the generator. It has a remote controller in the galley to make life easy.

To store electrical power, Offbeat is configured with 3 Mastervolt Lithium “house” batteries under our bed to run our systems and each of the 80hp Yanmar engines has its own starting battery (which we can cross-link if we have a problem with one of them).

We can generate power in 5/6 different ways from:

  • Either of the two engines which have powerful alternators
  • Solar panels on the cabin top
  • Our Onan Generator (a small diesel engine driving a large alternator)
  • A Watt and See Cruising 600 hydrogenerator
  • We can also charge from shore power when at a dock (but this is fairly rare as we prefer to anchor)

We have 10 x 178W solar panels on the cabin top but in practice struggle to get much more than 500W at any time. Inevitably 1/2 are in shadow from the sails and boom most of the time and they produce less power when hot (e.g. in the Med this summer). It’s more effective to have the panels over the dinghy davits at the stern but this spoils our view so we put up with the inefficiencies.

The Watt and Sea hydrogenerator is lowered into the water when we are sailing, the propellor spins to generate power which is fed into the batteries. Like Solar it’s “free” power using the movement of the boat and the drag effect is also minimal. We carry spare propellors in case they break when we inevitably hit Sargasso weed crossing the Atlantic.

This shows the port engine compartment with one of the two Yanmar 80hp diesel engines and the Onan 9.5 kVA Generator on the right of the image.

Finally the power generated is passed to these two “Combi” charger / inverters which both charge the batteries and also have inverters to run the 240V systems on board. Two Combis again give us redundancy in case of failure.