Just finished and flew a Heinkel 31 on floats. Before I relocated the floats forward so that the steps are about 1/4" in front of the CG, it would not come up on plane. Now, it pops up in about 10 feet. (2.5 pound model with a Magnum 15) There's more to it than just step vs CG, but having the CG slightly aft of the steps is one way to easily avoid problems.