props and pitch
I just went through some experimentation with the prop on my boat (sorry, a Hunter 30 with a Yanmar 2GM) Here's what I learned from a variety of sources: -Small diesels want to run at 70-85% percent of max RPM or the mixing elbow clogs up with soot -If you don't know the maximum rated RPM run it up in neutral and see how high it goes. The throttle control sets the RPM NOT the fuel flow. A governor then adds fuel to achieve the RPM. -The prop pitch basically sets the maximum loaded RPM. You want this to be at about 90-100% of the maximum RPM without black smoke. Black smoke is from the fuel flow being increased without being burned because the engine is overloaded. With my boat, I bought an adjustable pitch prop and kept resetting it until the max RPM matched the 1 hour duty rating. I discovered about 1" of prop pitch change seemed to equal about 250 RPM change. Incidentally, lots of places will sell you a used prop of about that size for <$200. Are you in New England? I have a 13x10 on a 1 inch shaft three blade I wouldn't mind selling. BTW, the best way to slow your boat down is to let barnacles grow on the prop. Surprisingly little slows you a lot.
