If you have been reading here for the last 2 weeks, you may have come
across my 2 or 3 posts about my boat's overheating problems:
essentially, boat overheats for 3 to 5 minutes (at startup) and then
temp needle drops back to normal and everything is fine. It is a raw
water cooling system and the boat runs in sal****er. Because of
various tests and checks (including replacing the thermostat), I am
pretty sure it is not the stern drive pump/impeller, thermostat or
clogged hoses.

Friday, we decided to go to my (boat-access only) cabin. The boat
started beautifully, I put the boat in gear and away we went: no
problem whatesoever, the temp never went passed 150F (stayed pretty
steady at 130F). 25 minutes minutes later we arrived at the cabin and
I thought that perhaps my overheating problems were a thing of the
past!

NOT SO... After a celebratory beer, we decided to go drop the prawn
trap. Our preferred spot is only 2-3 minutes from our cabin's dock.
Well, by the time we got to the spot, the temp had creeped up to 220F!
The overheating problem was back! But that is not all! Now the boat
would not even restart! After numerous attempts, we had to be towed
back to our dock. Because the non-starting problem happened at the
same time as the overheating problem, we naturally concluded that they
must be related. But the next day, when the boat was cold, I tried to
start the boat (fully expecting that it would) but no luck! You can
tell that the battery is fine (trim and bilge works, engine tries to
turn over) but something else is preventing the engine from starting.
As far as I know, the cooling system should have nothing to do with
starting the motor (especially if the boat has already cooled down) so
I am now thinking that this is a totally new, unrelated problem.

My friend thinks the starter might be broken (he said he had a broken
starter on his Jeep and it acted/sounded just like the boat).

Anyway, after dropping the prawn trap on Friday afternoon, I never
managed to restart the boat and we had to be towed back to the marina
(big thanks to my neighbour at the cabin) on Sunday.

What do you boaters think? Related or unrelated problem? Likely that
it is the starter or not? How can the boat perform flawlessly (at 130F
with good oil pressure, etc.) for 25 minutes and then overheats to 225F
next time I use it!? How can an overheating problem be so random?

Anyway, this is now all beyond my level of comprehension and I am
trying very hard to book a mechanic. The problem is, even tough I live
in a coastal area (Vancouver, BC) where one would think there is a
large supply of boat mechanics, finding an available/willing mechanic
around here seems to be harder than finding Bin Ladden!

Anyway, as usual would be interested in your feedback and comments
about this very weird situation... Cheers! Andre