Gas outboard and diesel generator is what Back Cove is doing with their outboard series. The 34o has twin outboards, the 39o has triples. They have separate 25/23 gallon diesel tanks. They seem to be selling well and attracting a different type of buyer.
Yesterday I read an article about the Hylas 47 Motor Yacht. It's powered by twin diesel outboards, vs. what would be 3-4 outboards if they were gas, because the diesels have to much more torque at lower speeds. The boat is reported to have a top end of 35mph and cruises at 19 mph. For along time I've thought a diesel outboard could make a whole lot of sense from an efficiency view, both for fuel burn and number of engines hanging off the back. This boat does seem a bit odd to me though; its super light (too light?) at 21,000 lbs at 47 feet? My boat is 37 feet (well, 42 overall) and 22,000 lbs.
