Harald E. M

The maximum torque occurs at around 2,250 RPM, which is also the point of optimal diesel fuel consumption. Above that, fuel consumption increases and torque decreases—making it inefficient. You can notice a significant increase in performance (speed) when going from, for example, 1,800 RPM to 2,250 RPM. This has been our standard operating procedure for 40 years and 3,300 hours with a two-bladed propeller, 17 cm in diameter and with a pitch of 11. We will install a three-bladed propeller with the same pitch to reduce propeller twist during reverse operation; it remains to be seen what the values will be then. Note: Attached is a graph showing power, torque, and fuel consumption for the VP. A small addition: For older engines from the ’80s and ’90s, the rule of thumb for optimal RPM was 2/3 of the maximum RPM. For the VP 2003, that would correspond to approximately 2,133 RPM (3,200 * 2 : 3).