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post #76 of Old 05-01-2014
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Re: Repowering with an electric engine?

The only electric I would ever have is a pure one - no generator. I wouldn't want to carry gas for a Honda gen and certainly wouldn't pay for a diesel gen and electric drive as that is much more expensive than a new diesel by itself. A hybrid system is not worth the investment in any case as the gains are very small on a sailboat. Pure electric drive works for someone that will plug in to shore power after a daysail or weekend trip. It does not work for a longer range cruiser. Here's why:

Range - with my small diesel and a 12 gallon tank I have a 300+ mile range. 2 five gallon jugs of diesel almost doubles that range. Electric cannot come close. In the area I cruise a 2 week holiday in Desolation Sound is an impossibility without going marina to marina - one problem is there are few to be found, one of its great attractions. Our summers are known for light winds and there are narrow passes with strong currents in abundance.

Weight - one gallon of diesel = about 1000 lbs of batteries. My engine weighs under 200 lbs and even with the full fuel tank weight added in I would be grossly overweight compared to what I weigh currently and that would have a short range - see above.

Recharge - Everybody talks about regen charging but nobody will post numbers - it may work to a certain extent on a larger faster monohull or better yet multihull but it is ineffective on a smaller monohull. I would think it would be like bailing a boat with a teacup - a very small gain.

Solar - There isn't enough room on a monohull sailboat for the number of panels required for even reasonable charging of a 48 volt bank. Most cruisers struggle to charge the house bank fully with solar to meet demand. Remember because it is a 48 volt bank take the output you receive from panels at 12 volts and divide by 4.

Expense - The upkeep of a small diesel is considerable less expensive than that of an electric drive. Battery replacement about every 4 or 5 years if things go well. Equate this with normal house bank replacement at 8 years or better which rarely happens. Small diesels are both reliable and inexpensive to run for many years if maintained properly. Impellers and oil changes are not expensive.


Your post is worthless without solid numbers - bank size, range, and charging times/method.

The batteries we are beginning to see - LiFePO4 - hold a good promise for the future of electric drives. The cost with any appreciable range is currently about the same as a new car. But the ability to charge on a sailboat away from shorepower is still not there.

Living aboard in Victoria Harbour

Last edited by mitiempo; 05-01-2014 at 10:06 PM.
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