Here’s an update: I kinda dove on the boat yesterday. The primary lesson is that 40 year old rubber does not hold up (my SCUBA cert & equipment dates to 1968). but with shock cord holding the mask on and a snorkel I discovered the prop is fine (zincs too). Bewildered, I started the engine and leaned that observing the transmission/prop flange rotating is not the same as the prop-shaft rotating. Duh!
The prop side of the flange has 2 screw holes, one of which has a loose set screw (no wire tie on it) the other is vacant. Tomorrow I’ll uncouple the flange and inspect for a missing key - if there was one, I would expect to hear it rattling in there.
Charlie Lincoln • Cathlamet, WA • Islander 28