Just came from the boat
Went to the boat and dove in to check the barnacle situation. I'm surprised it drove the boat at all. It was covered with about 3/4" of marinelife. Twenty minutes of scraping and she was like new. Motored out and she seemed like a different boat. (The admiral has been bugging me about, "Don't you feel that vibration?" My thought was, "What the hell would she know about marine diesel engines?") Well the vibration is noticably reduced, the boat responds to the throttle better, and I took her up to 3000 RPM and no smoke or black water.
Thanks for your input. I will take your advice and start keeping a better engine log for future reference.