Presuming that you are a certified and proficient single-engine land pilot, the Single Engine Sea add-on rating requires only a few hours of training and, in the United States, a checkride with an FAA examiner. In the process, you'll learn to handle an airplane on the water, read the environment for wind speed and direction information, verify the suitability of a landing area, and secure the airplane at a beach, ramp, dock, or mooring buoy.