Torque peak vs. HP
When repowering last winter with an eye towards longevity and economy-I avoided Deeres warrenty insistance of proping to 2500rpm at WOT.
The 4045 non-turbo power curve in either Deere of Lugger reveals a peak in the torque curve in the 1200-1400 range of about 220 foot pounds-deminishing as revs increase to about 170 at 2200-2500 rpm.
The HP at 12-1400rpm is 50ish-and 80 at WOT, fuel consumption moves from -1gph to +4gph.
Disreguarding Deeres insistance, maintaining an operating temperture of 180 and oil pressure of 45+--I for one belive that it is torque-not HP that pushes a displacement craft and that prop sizing and transmission ratio balance so that you can operate your vessel in s/l range of 1.1-1.2 works best.
Most "trawlers" in my opinion have way to much HP and*way to small props-Either you tune the boat to the engine or tune the engine to the boat.
Find your torque peak-operate your vessel there by manipulating your running gear-be happy