[popr]

I have just bought a 17 foot ProCraft bass boat. I tried it out for the first time yesterday. I was quite impressed with the top end speed. 48 to 50mph. My question is, at what RPM should the 1991 115hp Mariner develop it's horse power? This boat has a manual Jack Plate. As you can see from a earlier post, I have no experance with jack plates. The boat runs at about 5600rpms at 48to 50mph. Is she turning too high? When I bought this boat, it came with four props. So he was looking for all the speed he could get out of the boat. The prop he bought and just installed on the boat, was a HIGH FIVE, five bladed stainless prop. He had to sell the boat to get money, so he had only tried the boat once this spring. He told me that the HIGH FIVE helped her. But I might want to lower the jackplate a little. I guess I am more concerned about not over turning the motor than top speed. It would be nice to have her run 50mph, but not if 5600rpm is to high. I have not looked on the prop for pitch and size yet. Not sure that I am going to spend any money for another prop. I have four now. It looks like he was doing the trial and error thing. Any help would be a plus. Maybe the lowering of the Jackplate is what she needs to bring the RPMS down, if they should come down. Maybe that is where she makes her full horsepower. 5600rpm ????????

[skier]

That motor has no problem turning 5600 all day. Just don't go above 6000. Around 5500-5700 is when she is giving all she has. It is a sweet motor isn't she. I think the inline 6 is the best engine that Mercury ever turned out.Happy boatingCraig