4. Don't be vigilant about inspecting belts and replacing them ahead of failure. ESP timing belts. Few diesels are clearance engines, meaning the pistons won't clear an open valve at TDC.. so if the cam stops and the crank doesn't, WHAM - 2200 rpm to zero in a heartbeat or less.
... don't ask how I know.... If you're lucky you'll just need a head rebuild.. but pistons may be damaged too.
In our case the belt was not old, but a nut vibrated off a belt guide fitting and fell into the crank sprocket, tried to go around under the belt and - SNAP - WHAM - STOP - silence.....
We were three days from home and limped back, sailing when we could and hip-towing our 40' 16,000lb boat with our trusty 5 hp Nissan on our inflatable when we couldn't.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)