My friend tried a .25 on his Senorita and couldn't get off the water in a dozen attempts. He tried everything, changing prop pitch, wing incidence, CG, Step to CG relationship, the works. We kept telling him he needed more power. He kept insisting it was a 20 size airplane. He finally switched out the engine to a 40 and made a nice flier out of it. Some people insist that you don't need more power with floats. Maybe not, but if you want to make your take off run less than a 1/4 mile I would suggest more power than you would use on wheels. Float planes are "dirty" both in the air and in the water, if you manage to get in the air you will really notice the tendency to stall in turns and it takes extra horses to pull through a loop. Good luck.