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Feathering and folding props
i use the stainless steel martec 3-blade feathering prop. it is much less expensive than autoprop or maxprop. it is easy to install and more importantly pitch can be adjusted externally without dissasembly. simply put, if you had to, you can go under water with snorkel, mask, box wrench and allen key and set the pitch.
pitch for reversed can be set independant of forward. you get excellent performance under power, great torque and control in reverse and near folding prop performance under sail.
i set my prop pitch on my beneteau 40 with perkins 50 engine to give me 6.8 to 7.5 konts at 2800 to 3000 RPM. Max rpm on my engine is 4000 RPM and the experts at mack boring say to ocaasionaly run my engine under load to no more than 3400 RPM.
according to them, if diesel engines are run too frequently at the same rpm, they tend to wear and score internally at that rpm. they suggest constantly varying the rpm. also - diesel engines like to and need to be run on a frequent and consistent basis. most diesels are good for 14,000 to 20,000 hours of operation. boats with low engine hours are not circulating and using enough diesel fuel which degrades quite rapidly. stagnant engine parts in salt air environments corrode very quickly.
treat your propellar system and engine system as one unit running and servicing both regularly.