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From: You can get an idea of speed???
Date: 05 Sep 2003
Time: 09:42:27
Remote Name: 156.99.90.179
To get into the 40 mph bracket with a 50 hp merc you need a least a 14 inch pitch prop. Merc rates that up to 42 mph. A 15 inch pitch prop is rated to go up to 46 mph. A 13 inch pitch prop is rated to go to 38-39 mph, and a 12 inch pitch is maxed out at 35 mph. Merc has always been on the optimistic side with their speed ratings. I had a 14 inch pitch with cupping on my 40 hp mk 55 on the 12 footer and it went 37 mph, but at only 5200 rpm. Prop was too much for motor, I dropped to a cupped 13 and got 40 mph at 5500 rpm. I think if I got ahold of a 12 inch and had it double cupped (it would load like a 13) I could gain a little as mercs like rpm and their horsepower goes up with rpm My speeds were checked with gps as I do not have a speedo, to inaccurate. dave.