Propeller size

[McGillicuddy]

Greetings and welcome aboard.

Probably no answers cuz 150 4-stroke is not a good idea in my mind. Too much weight.460 to 490 lbs.

140 Suzuki or 115 2,1L mercury can provide low 40s at 410 and 360 lbs. I'd seriously reconsider your power decision.

Guys running older 150 2 strokes in the 400 lbs class w 2:1 gear ratios are swinging 14.5x17 or 15x15 stern lifting props. Probably swing more pitch with the 4 strokes due to gear ratios designed to overcome extra weight and alleged inefficiency.

Again, reconsider - 150 4 strokes are about 160 to 190 lbs more than what the boat was designed for. Speed gained is not worth the performance loss. The 20 is a heck of a little boat, when properly rigged.