bestfish
Lieutenant Commander
After the great discussion about repower options, hp vs torque. Here's my situation. 36' Harris cuttyhunk, royal Lowell design (think cross between 32 holland and 35 Bruno), I was running a 420 cummins with a 2:1, 29x29 wheel. I had a cruise of about 16.5 and 19.5 wot. For a couple reasons, (the main being $) I put in a 6v92 550hp with a 1.5:1. I'm at least a year away from launching but here's my train of thought because all i can do right now is think about it. With keeping the same wheel I previously had a wot shaft speed of 1200 rpm+/- that equaled 19.5 knots. Now with the Detroit and all it's noise I'll have a cruise shaft speed of 1300 @1900 rpm. Maybe somebody can give exact specs but I'm pretty confident the Detroit puts out alot more torque for any given rpm. I understand this is a heavier combo for sure, but I look at it as 3 decent size guys onboard. I had a brief communication with Lowell boats about it, they thought I 'might' get 20kt cruise. I've used the boatdiesel calculator and even adding 1000lbs to my displacement it gave me a cruise well above 20 more like 24. My goal is a 20kt cruise. If I get that I'll be happy. What do the pros think without shattering my dreams!?