Efficiency of Baglietto Ischia 80 or similar Vee hulls at low speeds

[yabert]

I'm planning on using Nissan Leaf drive units for the propulsion motors.

Interesting. Me too, but at 60V, not 360V: Electric inboard motor, my journey to find proper motor https://www.boatdesign.net/threads/electric-inboard-motor-my-journey-to-find-proper-motor.69574/

There's a lot I still don't know but I'll be taking the plunge in the next couple of years

Solar, battery and motor technology go so fast, things available in the next couple of years will be different than today.

 

[gonzo]

You should try to maneuver a cabin cruiser like the OP mentions in a cross wind and/or current. They need to come at fairly high speed into a dock and get slammed into reverse or they will be no control. If it has the minimum power to move at 5 knots in a calm day the boat will be underpowered when there is wind or current. In other words, not safe or even convenient.

 

[fredrosse]

The boat would be retrofitted with about 240–320 kW of batteries

Your units stated are incorrect, you should get this type of thing properly sorted, and understand the engineering concepts before proceeding.

As far as using a planing hull for displacement speeds, as a rough estimate about one horsepower per ton of total displacement will get you to :
Knots = (0.9) x Squareroot (waterline length,feet). For a good displacement type hull, (saiboat hull with a big propeller) you would get about 1.2 x SQRT(waterline length, feet).

That level of power is low, and any hull would be easily challenged by wind and weather.

These are crude numbers, but reasonable.