Originally Posted by edrnemt
I have a MT 34 with a Ford Lehman 120hp and a Velvet drive. I feel like I have extra engine and could get a few more knots out of it. Currently at 1800RPM, I get 6knots. If I go to full throttle 2250rpm I only get 1 more knot. What propeller/pitch should I have on my Trawler?
First your prop is over pitched. The engine should rev to 2,500 at wot not 2,250. A good prop shop can rework your prop to remove 2" of pitch which should get you close to 2,500 rpm at wot.
But that will make your speed less at 1,800 not more, but it will be lots better for your engine. Running it as it is pitched now is like lugging an engine in fourth gear up a hill whereas shifting down to 3rd will let it speed up and run better.
6 kts at 1,800 with an over pitched prop sounds like too low a speed. Is your bottom clean and/or the prop?
With your prop repitched you could run the Lehman at 2,000 rpm but it gets pretty noisy above that. 2,000 rpm should push a MT 34 with a clean bottom to 7+ kts.