J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Yanmar

Taras - the power, torque and fuel consumption curves from the Yanmar service manual are attached. You can see that torque and fuel consumption are pretty flat from 2400 to 3400 RPM. What these curves don't account for is the performance of the 2 blade Martec prop. I find that the "sweet spot" for best fuel efficiency and speed is about 2400 rpm. After that, the fuel consumption increases exponentially with small increases in speed. I'd find the RPM closest to 2400 where you don't have vibration from engine/drive train and use that. You can always increase the RPM for time when you really need the power, but no need burning excess fuel and placing excessive wear on the engine otherwise.