Generators aren't subjected to the load and throttle variances that your boat's engine is. Because of that the oil isn't collecting much in the way of combustion by-products or gasoline from cylinder washdown. So, genny oil simply doesn't need to be changed all that often
And really, we change our oil more often than necessary anyway. It's been proven (so I've read) during tests with New York taxi cabs that 10,000 mile oil and the engines its in showed no significant differences between 3000 mile oil & engines. And what's the average speed of a New York taxi while the engine's running, 15 mph? At 10000 miles that's 666 hours of engine time, and it's still 200 hours at only 3000 miles.
Frequent oil changes may be cheap insurance, but 50 hour oil changes do very little aside from keeping price of oil high. (just my opinion)
1988 SkipperLiner 53x14
1995 Tracker Party Cruiser 32 *for sale*
2003 Chaparral 260 SSI
2000 Allegro Bus 40' DP