[spareparts]

one thing to remember is to stay with the same style of prop when testing, sometimes when switching brands or styles, it can give completely different results. ( one of many examples)I was playing with a 26 Sea Ray once that had a 502, switched from a 21p Mirage(would hit revlimiter) to a 23 Vengence( only 23 I had), the boat wouldn't even plane off, kept blowing out. We had 23 Sea Craft that wouldn't turn enough rpm after we droped the engine one hole( coouldn't plane out in rough seas loaded), changed from a Mirage plus to a Vengence(same pitch), increased 400 rpm. Point is all the figuring and calculating you can do will only get you close, nothing beats bolting it on and trying it out. I would try a standard 19 P aluminum prop( QSS, Black Diamond, etc), there are planty around for you to try and if it doesn't work, they are easy to sell. Unless your running in a lot of sand, you probably will not be able to tell the difference between aluminum and SS. Check around for Honda props, some of them will go right on a Mercury( I know large hub for sure, not sure about small hub like your 125), they look pretty good, priced far below anything else, and their shape should create some good lift