The hybrid seen up close

The hybrid seen up close: hybrid systems for the nautical world.

In recent years we hear a lot about hybrid systems also for boating but what are they really?

This article comes from the nice statement made by a visitor to the Genoa Boat Show in 2016 when I heard while visiting a hybrid system set on a Sorrentino gozzo to exhale “because you advertise this boat as hybrid if it has an engine electric and one diesel?”

L'ibrido visto da vicino: sistemi ibridi per il mondo della nautica
Orca by Gbtec Hybrid System

Seriously the hybrid, mainly thanks to the efforts of several companies, is increasingly a reality, but the information about the benefits and feasibility of the same are very sparse.

In general, two or more different energy sources are used in a hybrid system to do a job; for our boats the work to be done is precisely the propulsion.

At this point we have to distinguish between Hybrid in Series and Hybrid in Parallel.

In the Hybrid Series, in fact, there is a simple conversion of energy, the diesel engine produces electricity that goes to charge a battery pack or comes directly to the electric motor that is the only organism dedicated to propulsion, in this mode you can also navigate with only electric motor as long as there is an adequate battery pack.

L'ibrido visto da vicino: sistemi ibridi per il mondo della nautica

Such a system is used on modern cruise ships, submarines, nuclear ships and of course pleasure in case the autonomy that the vessel must have are elevated and not reachable with a simply electric system.

It is often led to think that this is not a hybrid system that is advantageous for pleasure, while there is no doubt ingose the benefits for the Merchant Navy.

In fact the system becomes convenient especially for sailboats that manage to make ordinary exits with the sole charge of batteries made in the dock, by means of photovoltaic panels or while sailing being most of these Reversible systems: when sailing the electric motor acts as a hydrogenerator!

At this point, as mentioned above, the use of an endothermic engine for electricity generation only (diesel or gasoline generator) serves to make up for the lack of electricity in case of long motor crossings or need for more edge energy.

Studies on this application have shown that on average fuel consumption is reduced, but if this reduction is irrelevant for a sailboat that already normally consumes little, the maintenance savings that take place over the years become interesting.

An endothermal engine used as a generator, in fact, does a much more “simple” job than one of equal displacement and power used as a powertrain: it does not make any kind of acceleration, it does not need additional mechanical parts such as inverter and gearbox.

All this turns into a much lower ordinary and extraordinary maintenance cost.

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For those who have on-board engines and generators with very similar displacements and endothermic engine powers, they know what we are talking about.

This hybrid is feasible both on vessels under construction and on existing vessels as long as there are reasons for the new distribution of weights.

In parallel hybrid, however, both systems work on the same transmission line, in most cases an axle line; With this system you can only navigate with the electric motor, only with the endothermal one or with both systems.

L'ibrido visto da vicino: sistemi ibridi per il mondo della nautica

The electric motor can then act as a powertrain-generator and recharge the batteries of the propulsion system during navigation with the endothermal engine; It can also act as a booster of the main engine by increasing the total power delivered by the propeller.

This concept is very much based on the technology used in hybrid cars where the electric motor is entrusted with the propulsion of the car in the city or at low speed, the diesel one is instead entrusted with propulsion at speeds of more than 40 km/h; During the endothermic motor scheme or braking, the electric motor acts as a generator.

This type of system is having more attention in the nautical world for both disland and gliding hulls; In those dislosions the electric motor manages to bring the boat to cruising speed while the endothermic engine is used only for the extension of the autonomous, for the gliding hulls instead the electric is used for navigation in dislocations and endothermal one for gliding bras.

The advantages of this system are:

  • Fuel and maintenance savings from 10 to 60 (they depend a lot on the type of use and hull).
  • Navigation in Marine Protected Areas.
  • Maintaining the autonomy and the main performance of the vessel.
  • Silent navigation and no exhaust fumes for the electrical system.
  • Presence of an auxiliary engine.
  • Fishing in complete silence and at any speed you want.
  • Replacing trolling valves.

For the implementation of this system at the moment there are two different schools of thought.

The first European school of thought has designed very complex and heavy systems that intertwine between the main engine and the inverter/reducer: the greatest advantage is that being equipped with an electromagnetic clutch capable of releasing the connection of the electric motor from the engine shaft, they can also be used to produce energies when the boat is stationary with the help of the endothermal engine; They can also be installed with any type of thruster (propeller axis, V-Drive, Sail-Drive, Outboard, Hydrogetto, IPS, etc.)

On the other, they are very expensive systems even for all the mechanics necessary to make them work and the perforated battery packs they need; having a lot of mechanics are more easily prone to breakages, inefficient because they disperse from 10 to 30 of their power due to the efficiency of the transmission and thruster, the mechanics is subject to significant stress due to having to work on direct contact with the engine shaft.

L'ibrido visto da vicino: sistemi ibridi per il mondo della nautica

The second school of thought is the American wire that has designed very simple systems that base the transmission of motion on belt transmissions connected directly to the propeller axis: these are systems subject to very low maintenance, robust because they lack almost entirely of mechanics, light, efficient because they can transmit directly to the centerline all the power, cheap because they lack friction or complex mechanics and can be installed with any type of battery.

On the other hand, they do not allow the generation of energy with boat at the bottom and for the moment they are not installable with complex transmissions such as Within-Outboard, Hydrogetto and IPS.

L'ibrido visto da vicino: sistemi ibridi per il mondo della nautica

The last aspect is the Mixed Hybrid, which consists of integrating the concepts of the Hybrid in Series and the Parallel Hybrid.

A modern boat has the ability to recharge the batteries of the electrical system even in the dock, with photovoltaic panels, wind turbine, hydrogenerator etc.

In the mixed hybrid the engines are coupled in a parallel hybrid with regard to propulsion, while external energy sources such as a photovoltaic panel, are configured to recharge the propulsion batteries and therefore with the concept hybrid in series.

The hybrid seen up close: hybrid systems for the nautical world

Below is the example of integration on board for a newly built boat where you can make the most of all the technologies present in a Mixed Hybrid plant.

I hope you have come up with your own idea at this point but if you still have any doubts write in the comments