Gentlemen,
In determining the suitability of a hybrid drive for a sailboat one must consider the duty cycle of the diesel generator.
If the boat consumes small amounts of power, and the batteries are used as a buffer to the large output of a diesel generator, then it makes sense.
If the duty cycle is 10 to 1, then hybrid is an obvious advantage, the batteries won't get cycled that often so they won't wear out early, and the diesel generator will be charging the batteries at the diesel's optimum efficiency.
If the duty cycle is 1 to 1, then the hybrid is not advantageous at all.
It all depends on how you use your boat. It is my observation that the way boats are used in the Santa Barbara Harbor, that Hybrid Propulsion would be a great advantage. Most boats use their diesels very infrequently, some getting a tank of gas once per year at most.
One also has to consider the percentage of energy used by the house, and the percentage used for propulsion. With boats that use more energy for their house than for propulsion, once again hybrid wins because a DC generator is upwards of 3 times as efficient as a belt driven alternator.
The final remaining factor to determine if hybrid technology is appropriate for someones vessel is how pleasant life on board can be. Diesel Generators can be mounted in a lazarette - outside the living spaces of the boat. And an electric motor is far nicer to live with than a diesel - anyday.
My firm belief is that diesels make for a better motor boat, and electrics, be it battery electric, solar electric or diesel electric, make for better sailboats.
Now if I can only figure out how to automate the tracker for my 450 watt solar array......
Pictures coming soon
James
On Jul 22, 2011, at 10:27 PM, Eric wrote:
Hi Kerry,
So what you're saying is that installing a diesel-electric hybrid for purpose of gaining efficiency is a non starter becuase diesel alone is more efficient. I'm on board with that. I've never been a supporter of hybrids in our size boats, except in very specific use cases that aren't focused on efficiency.
I have heard that the most efficient internal combustion engines are giant (bigger than my 30' ketch) turbocharged 2 stroke diesels like this one.
http://www.gizmag.com/go/3263/
This type of engine exceeds 50% thermal efficiency, but I can't see putting one in a sailboat... :)
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Kerry Thomas" <kjthomas@...> wrote:
>
> Hi
>
> Not really correct. For a given constant speed application diesel alone is
> more efficient.
>
> Diesel electric drives are used for controllability in electric locomotives
> and ships that do a lot of port calls. On passenger ships and submarines
> they are used because generating capacity is just as important as
> propulsion. In the past they were also used as a gearbox because the gearing
> for really large ships engines did not exist.
>
> Now, the most efficient ships propulsion are very large direct drive
> diesels.
>
> In yacht sized power plants it would be very rare to gain efficiency by
> adding an electric motor between the diesel and the propeller. Of course you
> can have other valid reasons for doing so. Silent running. Weight
> distribution, Regen etc.
>
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