Electric Motors and Battery Size

[peter.bomberg]

Ok so this is a new by question but assuming a Privilege 51 weighing 15 Tons, it appears that two Thoosa 13000 should do the trick (http://www.asmomarine.com/2005/asmo_...OOSA_13000.pdf) they are 72Volt systems so assuming that I need the batteries wired in banks of 3 (based on 24 volt batteries), to get a 6hr motoring capacity I am assuming I need 50% of max current draw to sustain the speed (assuming dead calm as otherwise I would be sailing) so 6*100=600Amps thus I need to have a minimum of 9 batteries to give me 600Amps, they would weigh about 1,152lbs and to double the range I need to double the battery bank and so on.

Can someone who is better at electronics check this as if it's right then I am net zero for 6hrs of motoring versus the weight of 2 50hp diesel engines (of course a genset and solar panels) will extend the range but then how many hours of motoring should I be planning on is the next question as from my reading there can be a day or more on a long ocean crossing with no wind)

Advice and help needed!

Peter