Mercury 150 Fuel Mileage - 1971 20' SF

[Fr. Frank]

I ran a '92 XR4 150 motor on my 20' Seafari for a number of years. Remanufactured by AAA Outboard and Machine and produced 192-194 hp on the hydro-dyno.

I had a prop custom made by Powertech, 15.25" diameter, 16.5" Pitch, fairly aggressive rake progression, 3-blades, polished. I changed my lower from the original small gearcase to a large gearcase off a 225 Merc, 1.65 ratio, with nose-cone and low-water pickup from Bob's (already on the lower when I bought it)

Amazing hole-shot, planing in just about 3 seconds lightly loaded, and still under 6 seconds with 9 people on the boat (4 adults & 5 kids).

Slow cruise was 28 mph at 3300 rpms and achieved 2.7 mpg on a Navman Flow meter. Fast cruise was 34 mph at 4000 rpms, 2.3 mpg. My normal average usage over all as 1.9 mpg.

WOT in the right conditions (45*F, downwind in 8kt breeze, light chop, only 12g fuel on board, was 48kts (53-54) mph at 6050 rpms

BTW, I now get 5.3 mpg with the same hull, at 24 mph, running a 90 Optimax.WOT 33-34 mph.