I have been interested in electric propulsion for many years, and when I bought my new Manta catamaran 2 1/2 years ago, I considered an electric version. They had already supplied one using Solomon Technologies electric wheel system. It had not been a success!
The problem is, to maintain, say, 5knots for a substantial distance, you need to run the generator. That generator will consume substantially more fuel to achieve this than a conventional diesel propulsion engine. Don't believe me? Ask the propulsion manufacturers. Its hard to get figures, but it can be done.
The cost of the installation is substantially higher than an equivalent diesel installation.
The drag of the regenerative propeller charging is substantial. No problem if wind is strong, but it is otherwise.
The whole question of charging is important. Typically suppliers use high voltage DC motors as they are more efficient. However, this limits charging to the props or the special generator. Solar panels and wind generators are no use. Frankly it seems to me that it would be beneficial to sacrifice some of the benefits of 144VDC motors and use 24 volt, which can be charged from multiple sources.
I don't know why these systems are most commonly seen on catamarans (Lagoon 429 for example) where the weight of the battery bank is an issue. A monohull's ballast could be modified to compensate for the heavy batteries.
These boats also depend on one engine for everything. If that generator engine fails you are in trouble.
Where they undoubtedly work well is on a boat that lives in a marina with a shore charger, and only uses engine power to manoever in and out of the dock before and after a day sail. Perfect, you don't even need the generator. Very restrictive though.
There is not nearly enough information out there. Somebody should compare a Lagoon 410 and a Lagoon 420 on a side-by-side voyage in the same weather. Then we'd get an idea of costs and efficiency. I suspect Lagoon know, as they sail them across the Atlantic, but they don't publish any figures, only 'sales' talk.
Originally Posted by Nausikaa
Many of the regulars will recall that we discussed electric propullsion a while back. Well, this evening I found a company which offers electrical propullsion for yahts at a reasonable price. I am certainly going to asj for more information because when NAUSIKAA eventually needs a new enging (a long time from now I hope) then electric propullsion may be just the thing.
Check the site out. If nothing else, it is interesting technology which should only get better as fuel becomes more expensive and we become more environmentally concious.
Aye // Stephen