Thanks for the info. guys, much appreciated. I haven't tried 2800 rpm yet, however did find 2200 to be smoother then 2500 rpm vibration wise. Circe has fresh water cooling and a two blade Max-Prop. Using the GPS we were doing roughly 5.8 at 2200 rpm in no wind/flat water and averaging around 6.2 when we kicked it up to 2500 rpm (again based on GPS speed)
I will have to try 2800 to see what that is like from a vibration perspective.
Did some of the Yanmar's have different hp ratings in the J/30 ? I was assuming they were all 13 hp
