Electric drive is easy to do now the tech is all there and you can do regen when sailing by having the prop turn under water adding power back to the batteries. 5 years ago it was expensive and difficult to do. Now there is so much more on the market with a huge maker movement building electric converted cars. Good thing in a boat you don't have to go fast so the requirements are better for boat use. With some wind power or sea gen underwater prop for generating electricity.
As normal if you get sailing stuff they like to make the price higher so it is better to get stuff that is from other systems like for the electric motor a motor out of forklift will work just fine. Even an electric golf cart can be converted to use in a sailboat.
I am planning on doing the Great Loop in America from the great lakes down the Mississippi and then back up the east coast and through the canal back to the great lakes. The trip is 9,000 miles and the cost in fuel would be around $7,000 so it is way better to invest in a solar/wind electric drive system. I can do it for way WAY less than the price of fuel for that trip.
There is a ton of batteries second hand like out of salvage Tesla cars and many other places. The energy storage costs are going down each year more new tech keeps coming out that will make it cheaper lighter and more efficient.
RE: 7 years 7 seas - The boat