Yep, you need to shim up the front float legs by about 3/8" to 1/2". Oh, and get a plastic prop. Water spray will destroy a wood one if it has not already chewed the tips off of yours. Check balance, and make sure that it still balances on the same point that it did before floats. If necessary, add weight to the floats to balance. That way if you put it back on wheels it will still balance in THAT configuration.