Re: Hello fellow Starcraft fanatics
I have 21 foot chieftain similar to a islander with new 135 hp gm 4cylinder.
1.98 ratio outdrive
I run a 15 pitch 4 blade prop, I get @ WOT 28 mph @ 3900 rpm, 35 gallons fuel, 25hp kicker, 4 POBS ( full size adults 180+lbs each), 25-30 lbs lead fishing weights, and other fishing gear, 2 batteries, I am at sea level.
I cruise at 2800 rpms, 20 mph is where I seem to get my best fuel economy. I rarely ever run it over 3,000 rpms.
You should get 30 or better cruise speed and probably 35ish topend, all depend on your prop, elevation, and how much gear you have on board.