Renewable energy

While we are out at sea, a few thoughts on a subject dear to my heart – how we use renewable energy on a sailing boat.

The sails are of course the main way to harness renewable energy on a boat – the power of the wind is sufficient to transport you great distances without the need for an engine (you just need the engine for manoeuvring at the start and end of the trip). We have a mainsail, headsail (genoa) and staysail which when all in use can propel the boat through the water at speeds of over 8 knots in the right wind conditions.

The power of the wind can also be used to steer the boat, using the hydrovane (the red device in the picture below). You set this on the desired course and its rudder will steer according to the angle of the wind, removing the need for a person to steer the boat by hand, or to use the autohelm, which runs using the ship’s batteries.

Next on to electricity generation. The white device with the propeller next to the hydrovane is the Watt&Sea hydrogenerator. As Valent moves through the water the propeller on the Watt&Sea turns creating electricity. This can generate around 300W if we are sailing around 6 knots. The electricity goes through a controller and is fed into the ships batteries. To set it running while underway you do need to lean over the stern of the boat in a dangerous fashion to insert the pin, so it is advisable to set it in motion before you set off.

We also have flexible solar panels on top of our bimini (the blue cover over our cockpit), which continue generating electricity even on hazy days. On a sunny day the 2 x 200W solar panels generate approximately 1 kW of power per day, enough electricity to keep the fridge and freezer running. Again this energy goes through a converter and into the batteries.

Talking of batteries, Valent has 3 x 280Amp Hour Lithium batteries. These in conjunction with a 3KW inverter can provide enough electricity on board for all normal living, though it is not a good idea to use the electric kettle, toaster and microwave as these are all heavy consumers of electricity and the batteries become quickly depleted.

There are many other ways in which you can use renewable energy on a sailing boat. Some boats have a small wind-powered electricity generator, and many boats now have electric motors for their dinghies, which are charged through the sailing boat’s batteries. Although they don’t have as much horsepower as a petrol engine, they still have sufficient range to cover most local dinghy trips.

When away from a marina and therefore not connected to shore power, we need to use our ship’s batteries for all our power requirements, including running the boiler to make hot water, lighting, powering the Remoska electric cooker in the galley, running our watermaker which converts sea water into drinkable water, and running Starlink. (Our oven and stove top run on gas). Although our solar panels and the wave-powered hydrogenerator will partly charge the ship’s batteries, they aren’t sufficient to cover all this, so to charge the batteries further we use the engine or the generator, both of which require petrol or diesel. So our boat is still a long way from reaching Net Zero, but we are significantly greener and more self-sufficient than we would be if we were at home.