Definition of Loads Gross Total Weight (Hull/Persons/Equipment) Light 0 - 500 lb. range Moderate 500 - 1500 lb. range Heavy 1500 - 3000+ lb. range   The selection of the correct propeller will allow the engine to obtain it's full RPM as well as the designated horsepower. Engine horsepower is very closely related to the RPM that the outboard can obtain. In other words, if the outboard can not reach its specified RPM range, it cannot reach its specified horsepower. Once you have selected a propeller size that is right for your application, you may purchase a propeller from our aluminum props or stainless steel props on-line shopping section of this site. Please make a note of the part numbers listed below before visiting the shopping section as you will need to recall it. NEW OUTBOARD CUSTOMERS: New outboards under 40hp come standard with a factory pre-installed propeller - see chart for standard propeller size included with your model. Tohatsu does not offer a propeller exchange program.