Introduction

There are not many feasible techniques to supply electrical energy on board of a sailing yacht, which do not dependent on shore-bound supplies or facilities. Especially when moored in remote bays for days or even weeks, the energy supply of a sailing vessel may become a problem. The amount of electrical energy that can be stored in the on-board batteries is rather limited and will be exhausted after a few days without recharging the batteries.

The options to recharge the batteries with electrical energy are for example:

• An engine-driven generator or alternator. The engine may be the in-board engine or a special fuel aggregate. It will supply energy only when the engine is running.

• Wind generators are relative cheap wind-driven alternators capable of transforming wind energy into electrical energy.

• Solar panels are devices capable of transforming solar light directly into electrical power. The drawback is that they are expensive, bulky and susceptible to physical damage.

• Fuel cells are devices, which are capable of transforming chemical energy (e.g. stored in hydro-carbonate molecules such as methane) directly into electrical power by so called cold oxidation (in contrast to burning the fuel as is done in a fuel-driven engine).

The advantage of wind generators is that they are relatively cheap, reliable and robust and they are capable of generating electrical energy without the need of any external supplies. Also solar panels can be used to make a sailing yacht self-supporting in terms of electrical energy supplies. Although solar panels have a less favorable cost to power ratio, they are very reliable and require almost no maintenance.

The power system on small vessels is usually a low-voltage installation (typically 12V). This implies high currents in the cables used for the power distribution from the source to the different electrical loads. The efficiency and safety of such a high-current network strongly depends on properly sized cables both in length and diameter. These sizes determine the parasitic resistance of the network that may dissipate a large amount of energy if not planned and sized correctly to support the required energy flow to the connected equipment.