Previous posts have given specifications for the two different Yanmar engines used in the C387 series. Warren has provided below some additional interesting information on engine and transmission differences across the C380-C387 series….
Should you want to delve further into engine differences, –in this case between the two boats—one design fact that has baffled me is why the two engines [in this case: 3, but the 2 Yanmars have the same trend] have opposite-trending fwd/rev gear ratios.
Specifically, the Westerbeke 42b has 2.63/1.95 fwd/rev gearing, while the Yanmars [JH3] has 2.61/3.16 fwd/rev reduction ratios!!??
It looks like Westerbeke realizes that owner/operators want to operate at low RPM’s in reverse, but Yanmar believes operators like to operate near the same throttle for both directions???
Have asked a couple of “experts”, but no definitive answer. Perhaps Tim has some thoughts on this.
To carry this a bit further, I see that