Electric final drive

Do you have the room in a 44 ft sailboat to store 10,000lbs of batteries without having an adverse effect on the vessel?

Lead weighs ~700 lbs per cubic foot, lead acid batteries weigh ~100-150 lbs per cubic foot. On top of that they are inconveniently shaped to be poured into a keel. In lead acid that equates to something like 150 kWh if you are willing to run them down all the way. Other batteries will do a lot more for you, but cost more and have higher bulk to mass ratios (lower density) which is cool if you've got a lot of room but less so on a cramped sailboat.

Diesel electric is a better choice perhaps for a sailboat that doesn't have a nuclear reactor but does have constant access to combustable air. Diesel electric allows you to tuck your diesel engine where it is least inconvenient for you and route heavy copper cables down to the drive instead of letting shaft alignment dictate where you put your iron topsail.

Unfortunately the electric motor itself is going to have some bulk to it, so if you get a unit that it outside of the boat in a pod (saving yourself the difficulty of working with fragile shaft seals) you pay the penalty in extra drag while you are using the boat for its intended purpose (sailing).

I don't know if there are any large enough for his application but there are electric drives and thrusters that don't have any kind of seal on any moving part. If you pot all the electrical components in epoxy water getting in between the field windings and a permanent magnet or potted induction rotor doesn't actually do anything.

That said I was thinking more about the fiddly work involved in installation than the rare failure. An electrical unit bolted onto the hull is a lot more forgiving of a few milimeters worth of mistake than a prop shaft is.

Both configurations have their advantages and disadvantages.

Not to mention, do you know what 10,000 lbs of batteries would cost every 3 years to replace? A diesel inboard sailboat is pretty darn cheap to operate when it comes to fuel...... Besides, you're supposed to be using the wind anyways!!!!!!!!!!!!!!

Since that 10k pounds of ballast already exists in a form and location that works very well, any attempt to relocate it higher and distribute it around the water plane will likely create more problems than benefits.

With regard to converting a very small recreational sailboat to electrical propulsion, it is difficult to justify the added complexity, reduced reliability, and increased costs for so little (if any) operational benefit. It is a tinkerer's dream though and would be lots of fun but that is about the extent of how it might be justified.

I guess if one is interested in having a 44 foot deep draft equivalent of a Duffy then replacing the diesel auxiliary with batteries, controls, and a motor would be interesting but given that most sailboats that size probably spend as much or more time motoring than sailing it wouldn't add much utility. Without some means of onboard charging or more batteries than the boat could float or anyone would care to live with, motoring time (especially against any kind of wind or seas) might be extremely limited. This takes you back to hybrid diesel electric along with its cost and complexity. As anything but a hobby or recreational experiment what's the benefit? If the novelty of having an electric sailboat or modifying one as a learning exercise is the objective then it would be a fun way to spend spare time and money.