11.1 volts x 990 kv at 90% efficient gives you approx a max rpm of 10989 on an 11x6 providing you are within specs of the motor and ESC and can achieve the rpm on that prop your maximum thrust is about 3.67 lb @ 337 watts, if it's the cub I think it is (blue and white) then it should weigh 5.5lbs less floats so that gives you about 60 watts per lb so I would imagine it would work but your power train will be working very hard at least on take off . . . (and this is less float weight and trying to get of the water)

I think the above is correct, anybody else?

If it were me I would see if could use 4S on your motor and ESC or go up a prop size?

Check out this web site . . . [link=http://personal.osi.hu/fuzesisz/strc_eng/index.htm]http://personal.osi.hu/fuzesisz/strc_eng/index.htm[/link]

Scott