Lehman 120 Engine quits at worst possible time

[Wilbur]

I am looking for the usual excellent advice I get on this site.
This is something way above my pay grade.
Setting the scene.
I am making my way out of Hamilton Harbour, under the lift bridge through the canal into Lake Ontario.
I am on my way back to Toronto
I replaced my my circulating water pump earlier (bearing shot) and everything is fine for the first 7 miles.
About a mile from the end of the canal I start losing power a little at a time. After 3 minutes the engine the Lehman shuts itself down.
I get towed back to Macasa Bay Yacht Club. All kinds of advice there as there is in any club.
I try to turn over the engine and the starter shuts down after 2 seconds. It seems like it won't turn the engine over.
Some suggestions are; one cylinder is full of fuel, another is the starter is shot, another is the injectors need a good cleaning.
What say any of you trawler experts?
The only diesel mechanic worth his salt is away until after the Labor Day weekend. He can come next Wednesday !
Is there anything I can do to prepare in advance?