Hydrogeneration

What is Hydrogeneration?

Hydrogeneration involves using the movement of the multihull through the water to generate electricity, usually by turning a propeller connected to an alternator or a reversible motor. This can be a very efficient way of recharging batteries during long passages under sail. The first attempts at Hydrogeneration date back to the 1970s, but it was not until 20 years later that commercial solutions appeared, and finally in the 2000s that the boats’ engines themselves began to be used in reverse mode, i.e., when the motor isn’t actually running, it can be driven by the propeller in the opposite direction and becomes a generator.
There are several Hydrogeneration systems on the market.

Four Different Systems

Towing Propeller

This is a small propeller mounted on a swivel arm at the rear of the multihull and connected to an electric motor to generate electricity. Either a folding two-bladed propeller, a three-bladed propeller optimized for drag, or an automatic variable pitch propeller is used to maximize efficiency. The towed propeller is easy to install as it is an independent system. However, the cost ($ 1,000 to $ 3,000 remains somewhat high.

Hydrogeneration by Towed Turbine

This was one of the first systems used: it consists of a small turbine attached to a line and towed behind the multihull. The main advantage is once again its simplicity of installation and a decent return. However, it creates significant drag and there is a real risk of loss or entanglement of the line during bad weather or when tacking or gybing, for instance.

Hydrogeneration propeller integrated into the inboard engine

This is the most widely used system today, as it is often installed directly in the factory during boat production. It consists of an electric motor that can operate in reverse mode and a specific propeller. The advantages are obviously that the system is integrated and operates almost automatically or on demand, at the touch of a button. This technology ensures that the batteries are recharged regularly, and the propellers used limit drag. The downside is that the multihull must be equipped with a suitable electric motor and the entire system must be designed and installed at the factory from the outset.

Hybrid Hydrogeneration/Submersible Wind Generator

This is a system that works using a submerged wind generator or a special turbine that also operates in generator mode. This technology is found on some racing sailboats, but its use is still relatively limited.

Components and Efficiency

For the system to work, it must consist of an electric motor that can be reversed to become a generator, a special propeller that turns under the effect of the water flow while sailing, batteries to store the energy, and a controller to manage the transitions between propulsion and generation modes. As for performance, the figures vary greatly depending on the type of propeller, the motor used, and even the shape of the hull. ...