I think this needs clearing up. To make 180hp for even 15 minutes takes a massive complement of batteries. Lithium Ion or Lithium Polymer have the best capacity/ weight density's. 746 watts equals 1 horsepower less motor efficiency which on todays brushless motors can be as high as 90%. About 150,ooo watts for 180hp. Volts x amps=watts.
I found some Lithium Ion 12 volt batteries on the net which are 300ah. They cost $3500 each. To get anywhere near the power needed without running major amps voltage needs to be upped, say to 360. At 360 volts we will need 420 amps. 360 x 420 / 746 x 0.9 = 182 hp.
30 x 12v batteries will be required. I theory this will give 360 volt 300ah pack, notice I said theory, in practice you won't get an hours capacity pulling 300 amps.
We are now at a cost of $105,000. We have the power to pull 180 hp now but not the capacity for an hour. About 43 minutes.
I am sure there are custom battery packs available at a more reasonable cost but you are still looking at a shedload to run for any sensible amount of time.
To put a further emphasis on this point a gallon of Petrol (US) has 124,000 BTU's
A Kilowatt Hour of electricity has 3,412 BTU's
Been a long day so I hope the math is correct, but you get the idea.
No electric powerboats in the near future!