How can I tell if my boat has the correct propeller(s)?

At wide-open throttle and optimum trim angle, the engine RPM should be within the manufacturer's recommended window —generally a range of 400 RPM (e.g. 4400-4800). Please see your engine's operator manual for more information on specifications. Using this methodology, the low end of the range will be realized under less than ideal conditions (i.e., heavy load, hot/humid weather), while the high end of the range will be achieved under ideal conditions (i.e., light load, cool/low humidity). Refer to the Prop Chart in the Vintage Formula section for original propeller specifications for your boat model and model year. updated: 4/1/2008