How fast should it go?

I have a 18 foot Crestliner Sportfish with a F150 Yamaha. After the break-in I could pull a 48 MPH GPS speed with the boat. Now I have about 80 hours on it and exactly the same conditions I can only pull 45 out of it. Does anyone else have that same setup and what are you seeing for speed. I was told that I should be pushing just over 50. Running out at max RPMs (6000). Maybe it is the wrong prop on there (14.25 X 19). Wondering if I should bring it in to have them look at it. I thought they would get better with more hours on? Any help would be great. Thanks

I can’t answer your question specifically but remember with warmer air temps, and warmer water, you will lose power vs Spring air and water temps. I’ll run mine out this week and see how it compares to Springtime as well (F150 on Lund 1700 Fisherman). I’m running a 19 inch SS prop as well, not Yamaha, and pull 5600+ rpm.

I Have a 98 1850 Tournement Pro Crestliner, same Hull with
a 150 Johnson. the best I can get is half tank of fuel emty live wells is 49 GPS. Three big guys + gear, full fuel and livewells 42. I have a 17 pitch prop very quick out of the hole.

Your Yamaha will loose a little horsepower with the warm moist air like we have right now. A four stroke engine likes cool dry air to get the most out of the engine. I notice on my F75 I will loose about 3-4mph from winter/early spring to summer. Also with warmer water temps the water isn’t cooling your engine down as much as it would if it was spring or late fall either. This makes the engine run a little hotter and looses horsepower….