Join Date: Jun 2006
Thanked 2 Times in 2 Posts
Rep Power: 12
I'm with you, Andre. Max. RPM is only for emergencies. High RPM (2,800-3,200 RPM in my case with max being 3,500) would be to blow out the carbon or if I had to go seven knots (just short of hull speed) for some medical reason, say.
Or if running a day at a knot more would take me 24 NM further away from a cyclone, maybe...
If I can't use the sails, I motor, but I want to motor to a sweet spot in the fuel economy curve. That last knot of speed tends to cost 40% or more in fuel in my experience, and so I find a "flat five" knots at 1,900-2,300 RPM (depending on seas) works quite well for me. Usually, I motorsail at 6.5 knots, of which 4 knots is engine at 1,600 RPM or so and this is because it's worth 10 dollars of fuel to me to run the engine up to temperature for two hours if I'm using the big boat for light-air sailing.