I recently picked up a used 2005 Mercury 115 Opti on a Fisher Hawk170. The motor tops out at about 4750 RPMs according to the gauges and goes about 43 mph. From what I have read this seems like a low RPM max. Any suggestions on what to look at first? - or is this OK?

Also what brand prop. I had Mercury 115hp 19 pitch black max prop and ran 46, got up to 40mph super fast.

I recently picked up a used 2005 Mercury 115 Opti on a Fish Hawk170. The motor tops out at about 4750 RPMs according to the gauges and goes about 43 mph. From what I have read this seems like a low RPM max. Any suggestions on what to look at first? - or is this OK?

Your tach is off.. Check the back of it and make sure its set on the right poles.

I see the following stamped on the prop:
48 77350A45 23P this is on the outside and I see 12.5 X 23P on the inside.
Is this just too much pitch?

I see the following stamped on the prop:
48 77350A45 23P this is on the outside and I see 12.5 X 23P on the inside.
Is this just too much pitch?

I quess you tach is right. Go to a 19 pitch prop that will put you right where you need to be. I'm very surprised that someone would put a 23 pitch on that setup.

Thanks, makes sense. I picked this up very recently so no idea why others do what they do and I'm obviously new to this game. Any specific suggestions on the 19 pitch prop?
Much appreciated.

Beeman,
Just pick up a stock Mercury 19 pitch aluminum prop and do some testing.

I am guessing that this prop would work very well for you. The purchase of an aluminum prop would allow you to do some testing and verification that all is well with the motor and prop at a lower cost.

If you get things dialed in, you can then go out and pick up a stainless prop if you like.
But, for that motor, performance will not be affected very much, whether you run aluminum or stainless. If you want durability, go with a stainless prop. i.e. stainless is much tougher and can better stand low speed bottom strikes compared to an aluminum prop. Performance will not be much difference on this boat and motor - if you have the right aluminum prop, compared to the right stainless prop.

Good luck
REW

I took it out on Green Bay today and much better. Got a little over 5200 RPMs and picked up a few MPH with a couple guys, gear and some decent waves. (Fishing was not good today)
Thanks for the help.