Kubota's Z 'super mini series' & related horizontal thermosiphon engines (2cy is a sweet spot but there are other 1 and 3cyl kubota options outside of this range also) are nice, simple and very lightweight for the small diesel ~10-15hp water cooled genset option. I don't know what specific models of gensets these engines are put in currently but there are many. I'd much prefer that to any gasser. The noise factor can be mitigated with a quality installation in a lot of cases. Any decent diesel gen options do tend to be expensive unless used/surplus. 1cyl might have slightly better efficiency & lightest weight but usually 2cyl diesel is a better overall option noise/vibration wise.an elegant solution for long distance sailors could be a very small, quiet, petroleum-fueled engine. Something elegant. 3 to 10 hp could be plenty with a battery-electric drive. Something is amiss with the marine diesel generator offerings as they tend to be complicated, noisy, and expensive. Think a “Honda” generator but without the volatile gasoline.