Hybrid Diesel Electric Propulsion

If you haven’t heard yet, several cruising catamaran sailboat manufacturers are selling or are researching alternative propulsion techniques that minimize the use of gas and diesel. For example, the Lagoon 420 features a hybrid diesel-electric system. The African Cats FastCat 455 Green Motion is similar.

Wouldn’t it be nice to travel without using fuel? Lagoon claims you can run on batteries at full speed (10kW per motor) for about 1 hour. If you add solar and wind generated power I am sure you could go farther without running the generator. How often do you need to travel for one hour or more in general? If you are in the doldrums you may need to motor more then an hour, but at least you will be doing it more efficiently.

With the combination of Solar, Wind and Water driven power generation it may be possible to go from A to B without using a single ounce of fuel. With today’s gas prices this makes so much sense. Who wants to hear or smell and noisy diesel running. There is no motor to start. You just turn a key and go. I wonder if you can run the microwave without starting the generator?

The Lagoon 420 Hybrid system uses two electric motors, a generator and a bank of batteries. Under sail, the propellers are driven by the speed of the boat and recharge the batteries. Add Solar and wind generation, and you may never need to start the generator unless you need to run your AC or washing machine. Very little maintenance is required compared to most cats which come with two engines and a generator.

What if the generator failed? You would have to rely on sun, wind and the water to power to charge the batteries. What if the Electrical system failed and you had no power to the motors? If one motor fails you still have the other. Lagoon stores energy in 2 separate banks of 6 batteries each which can be isolated, dedicated entirely to driving the electric motors. (Safety measure: in case of battery failure, one single bank can supply power to one or both motors). I am still not entirely convinced that there is enough redundancy so that you always have propulsion, however I suppose similar problems can potentially happen on any propulsion system. The question is which is more reliable.

How much does this system cost you long term in comparison to the traditional twin diesel’s and a generator? Lagoon claims the only maintenance on the electric motors is to replace the motor bearings at 20,000 hours or more. Batteries don’t last for ever and will need to be replaced. Diesel engines don’t last for ever either, but which will cost you more long term? With todays fuel prices these hybrid technologies should pay for themselves. Lagoon says they are working on the possibility of using Lithium Ion batteries which looks promising : 1/3 the weight, 1/3 the size, and an expected life of 8 to 15 years, with a capacity loss of 20%. The Cat is slowed less then 1 MPH by the spinning propellers, however once the batteries reach a full charge they will free spin. The African cat offers retractable propellers which will improve sailing performance while not charging batteries.

Is the power plant in you cat aging? Is it time to replace old engines? Perhaps you should consider switching to Electric motors. In that case you might want to contact OSSA POWERLITE. You can check out two of their projects, the Moorings (Robertson & Caine) - 43' eLeopard . View video footage at of the boat here. They are also working on a Alwoplast - 47' Crowther Catamaran.

I will seriously consider diesel electric and hybrid technologies in my 1^st Cat.