Proper care and maintenance of your boat propeller is just as important as engine care.  A boat prop that is not in good condition can cause many problems such as roughness, cavitation, corrosion and surface damage which reduces it's efficiency and hence raises fuel consumption and can cause other costly damage.  A propeller is an important part of any boats equipment.  NEVER run your boat for long periods of time with a damaged propeller as you may cause sever damage to the propeller from "cavitation burns" or bushing failure. Extended use of a boat with a damaged propeller may cause damage to your engine or stern drive.  Apart from seeing obvious blade damage, symptoms of a damaged propeller are vibration, loss of speed, apparent slipping (cavitation), loss of power or poor fuel economy.