With the transmission on the PS boats you need to leave it out of gear while sailing.
Why does the transmission have to be left out of gear while sailing? I have not run across that in the Yanmar material that I have for my 3HM35F with a KBW 10-E clutch.
I have painted marks on the shaft between the coupling and gland that correspond to the two blades of my prop. I also have a mirror in the engine compartment that lets me see the marks through the opened door below the companionway steps. I look in while my wife shifts in and out of gear until we get the marks stopped in the right spot to have the propeller up and down. I think the boat goes faster; she does not. Both of us think it a lot less noisy and much easier to sleep when sailing at night with the propeller stopped.
1988 PSC 34