I have heard various things about using a larger than necessary diesel engine to power a vessel. specifically i'm referring to a full displacement trawler (21 ton) operating on a single screw at low RPM utilizing a less than a 100 HP engine (as the designer recommends).
setting aside the extra cost of a larger engine than needed and the lost fuel economy, is it bad for a modern diesel engine to be run under loaded?
i have heard it both ways. yes- the engine needs to be properly loaded to run efficiently and maintain its well being and avoid internal build up.
I have heard no- modern engines, particularly turbos, suffer no ill effects being run continually at low RPM.
As I shop for used engines, i find very few for sale in the 100hp range. however, there seem to be many 6bt's and comparable lehmans in the 200+ range at good prices.
what say you?