Over Hill Sailing Club
Join Date: Feb 2009
Location: Adirondacks NY
Thanked 108 Times in 105 Posts
Rep Power: 8
Re: what kind of headwind should a sailboat be able to motor through?
If your engine won't turn more than 2300 rpm at full throttle you may be over propped, or at least have a dirty bottom. You should be able to get at least 2600 out of that engine.
My Yanmar two cylinder will rev about 2700 when conditions are right, i.e. clean bottom, smooth water, etc. That being said I don't think she would push me anywhere into 30 knot winds without falling off and getting some sail assistance, especially with a fierce chop.
The only time I've seen smoke out of my engine was when trying to get some more speed out of the boat when she had a fouled bottom (and propellor). Just had to throttle back and live with it until I cleaned her.
That sounds right, about 500 rpm low and therefore not able to get up to the top of the torque curve/ burning fuel inefficiently.
Lots of things determine a boat's ability to head into the wind under power, including windage of stuff on deck, canvas, hull shape, etc. If you're heading into a 30 knot wind, the waves are usually holding you back more than the wind and that is a hull shape issue.
Alberg 35: With a philosophical flourish Cato throws himself upon his sword; I quietly take to the ship.