I have owned boats since i was 10 some 65 years ago. I have always tracked the fuel consumption of my own boats under varying conditions. But I have never seen a discussion or forum about the relative fuel consumption of different diesel engines. Now looking at a boat with Cat C12 s and the Cat manuals say something like 20 litres (5 gals) per hour at idle and 50 litres (13 gals) per hour at 1250 revs, for each engine which I find very high consumption. What am i doing wrong here.? Any C12 owners out there top give me a hint on consumption, please.