Hi all, I refurbished a Model Boat plans Dreadnought a while back and that had 2 off 5 pole 385's running on 6 volts. This boat, at about 30 inches loa, would be about half the displacement of your one. Performance of my one was fine and it went forever on a 6 volt SLA battery and one 10 amp esc.
When buying an esc to run on 12 volts make sure it is suitable. Most of the cheap esc's top out at 8 cells.
I recently bought a new to me type esc recommended on another thread that was for 12 volts. It is only meant for lightish work (10 amps) but it does not have a heat sink and weighs just a few grams and works well for me. (I think I found it on Bang good .com)
The only diiference to the usual esc is the power connector, it is not a Tamiya white connector but uses the same connectors as the red 4.8 volt leads that are i/p power to receivers. I bought some red leads very cheaply and made up a conversion plug / socket. You could easily cut the leads and connect the smaller red leads.
One point to think about is the prop tubes, the usual brass ones are rather large in diameter, I have been using smaller diameter prop tubes but still with an M4 thread shaft (or 4BA).
The advice on prop versus motor diameter usually works, but I would go for 25 -30 mm pros with a big pitch. Some of the plastic ones are very fine pitch and will get you nowhere.
Do not use the very small U/J connectors as they easily fracture at the spline part of the unit.
The larger ones are much stronger and you can buy the 2 brass parts to customise to your requirements. I think the 385 shaft is 2.3 mm diameter and M4 is readily available or if the drive end of the prop shaft is plain then that will be 4mm dia.
Hope this helps, sorry can't remember the exact ESC type but it was mentioned in a thread about 6 weeks ago and I went on the web site and bought the 12 volt version. £6 or so I think.
regards Roy