The 10 inch will work awesome for the Cub. On a C pack you will have plenty of power to pull yourself out of any stall situations you get into. It also has the advantage of increased air flow to have more control surface authority then a smaller prop, helps make reactions more instant. And just a heads up, you will need more props then just the 2 that come in the pack, as a beginner you will be breaking lots of props. The floats might help some but there are always the unknowns