Re: Trawlers and simmilar types of boats
North Westerner 2510 Classic
It has a tug-style cabin with good fuel economy. It's 26' though. Maybe too small for you.
www.Hybridboatcompany.com
Re: GPH Cruising w/~26' Boat
The North Westerner 2510 is a 26' semi-displacement hull boat. At about 8 mph, you use around 1.4 gph.
http://hybridboatcompany.com/SPEED%20AND%20RANGE%20SPECS.pdf