[Fr. Frank]

These guys are telling you straight. I used to have a 1974 23' Tsunami (same as the Sceptre), running a single '88 225 Johnson Looper swinging a 15x15 OMC SST prop. Cruise was 23 mph at 3600 rpm, at 2.1 mpg on the NAVMAN. WOT was 38 mph at 5800 rpm, at 1.7 mpg. Motor was mounted on the transom on bottom notch (as high as it would go), water level at cruise rpm was just under ventilation plate, which was completely clear of the water.

Boat previously had twin '86 Johnson 140 hp Loopers under the PO, and his log showed he used to cruise at 4000 rpms at 28 mph, and WOT was 42 mph at 5600. No idea what the fuel economy was or how high the motors were mounted.

IMO. Single 250/300 is the way to go. I prefer Etec and Optimax to 4-strokes, but that's nothing but a preference.

For the record, I have fished many times on a '77 center console jack-shafted diesel. Boat was repowered at Frank Brown's from a gas Ford V8 to an '81 Volvo-Penta 140 hp 4-cylinder turbodiesel, cruised at 18-20 mph, and was WOT at about 26-28 mph. Owner claimed an economy of 3 to 4 gph at cruise, giving it better than 5 mpg. With no trim tabs, it took a while to get on plane, but once there would stay on plane down to about 10-12 mph.