That means a big boat.

Thanks to all posters for feedback.
I have the luxury of a big cat and big battery bank.

I'm not worried about the fridge , it's maybe 300W/24 hrs average in tropics
and half of this in the north.

As for the cooker- two hot plates at 1KW each seems a lot but given you use it
for 1 hour/day it translates to something like 2kW/24 = 83 Watts average @ 24
hrs and I think it's well worth it given the safety,cost, convenience and
simplicity advantages.

Same goes for coffee maker etc.

I did do my math before posting here and I understand how amps/watts etc add up.
I agree higher voltage would be nice but we are stack with 24V and don't expect
to be running generator at all times. Also we have luxury of designing
everything from scratch as the boat is being built and can acommodate locations.
In other words instead of long thick wires we can make them short for equipment
which consumes a lot of ampers. I'm trying to be smart but not always
conventional with this.

I agree electric heater might be the most energy hungry element, especially if
the water has to be retained and temperature maintained in the tank for 10
people onboard.

This is something that I'm considering to built around hybrid solution.

I came accross this Webasto heater:

http://www.navstore.com/pdf/webasto/Webasto%20TSL17.pdf

What do you think?

Another thing is - I'm wondering if we need a water tank at all? It takes lost
of gallons to shower 10 people- it cost money and space. I remember seeing in
some country (not US) showers with built in electric heater element which will
simply just warm up water passing through a piece of the size of grapefruit.

Regards M