Q: I have a 2007 Glastron GT 185 with a 3.0 lier engine. I changed the factory 21-inch pitch aluminum prop to a 19-inch pitch stainless prop. The rpm at wide-open throttle is higher, but I didn't notice any performance change. Should I have gotten a 21-inch stainless steel prop?

John Bollinsgreen
Cedar Rapids, Iowa 

A: Glastron and MerCruiser technicians chose the original 21-inch aluminum prop on your boat as the most cost-effective optimum performer for most load conditions. A 21-inch stainless-steel prop would be your best choice for trying to improve that performance, unless you regularly haul full passenger loads and the tachometer does not hit max rpm. Your best overall performance comes from the prop that gets your tachometer closest to the wide-open throttle(WOT) specifications of 5,000 rpm on your engine.

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