Why change propellers?
A. The stock propeller with which most outboards are equipped is a compromise. Since it has fixed diameter and pitch, it is really limited in its use and it does not provide satisfactory performance for all the combinations of hulls and loads that will be encountered once it is installed. One important fact to note is that the propeller moves the boat through the water at a specific engine rpm, and h.p. is directly related to the developed rpm. The engine cover is marked with a certain h.p. rating but in most instances the full benefit of the possible h.p. is never realized. Along with the h.p. rating equal emphasis should be placed on the rpm at which the rated h.p. is developed. This, of course, is where the propeller comes into the picture. Outboard engines are designed to be run at peak rpm for full efficiency. Excessive rpm with its increased friction and wear is obviously harmful. It is equally harmful to run the engine so overloaded that it cannot achieve its rated rpm since thi
