C converters & battery for house loads at 24V. 
Nice, wish I had the space to build..
Since your building, hydrofoils would double your cruising speed and lower your amp draw, not to mention a smooth ride. ( Just a thought, since your in the building process ( it outs the saildrives but cheap way to extend the range).
You should cool your motors. If you can sleeve it and fill it with coolant or mineral oil then coil stainless tubing, place into pipe. Then run seawater through the pipe and out the hull to keep it cool without the corrosion to your motors. ( simple heat exchanger )
I would double the size of motors you think you need.. Most only run @ 50% before they start sucking the amps and the benefits are worthless speed vs amp draw at 100%.. Get something you can run @ 30-50%. Look at your motor specs and compare them. Treat it like a gas engine you can putt around at cruise speed or WOT. Fuel or Electric, she's gonna suck some juice.
As for rpms don't rely too much with rpms. ie. A10k motor might freewheel at 10k @ 0% load, but only using 50% and adding a load to it will bring it down further ( based on Amp Load ) you would need to gear final drive. With the sail drives you don't really have that option to control your amp/rpm, so your looking at a prop swap to match your motor.
Just pay attention to the motors spec sheets.
If your just sailing around the caribbean, I would try to gain as much power from solar with a smaller battery bank. If you can match motor output single or double, your going everywhere for free. Use your battery bank as a buffer between the system and a dc genset for backup power.
Anyway I know this post is a bit old, just wanted to throw in a few pennies.. Would really like to see the progress on your build.. I hope to be doing the same thing in tens years, assuming my mast is still standing !
