Cut out of work at noon and scrambled to the boat to hook up with friends of
ours, meeting them at the mouth of the Vermilion River with boat our boats.
We arrived first and once safely past the breakwall idled while waiting for
them. The trip was perhaps 15 minutes tops.

I started to smell something burning and saw puffs of smoke coming out of
the engine compartment. I shut down the engine and grabbed a fire
extinguisher while my wife threw out the anchor, then opened the engine
compartment to see smoke coming off the engine and to hear hissing and
popping. Gave it a shot from the ABC dry chemical fire extinguisher
thinking there may be a fire. Saw the temperature gauge pegged at 250F.

Radioed our friends who towed us back to our marina. The marina mechanic
checked to see if there was any foaming or burnt smell with the engine oil
(none) or oil in the bilge (none). Sigh, maybe a good sign, or at least I
hope so.

We ended up leaving the boat with our mechanic and spent the day on our
friends boat. After 3 or so hours I got a call from the marina, telling me
they checked out the engine (after letting it cool) and judge it to be OK,
although the impeller needs replacing. They said I could safely move the
boat to my slip if I wanted to until repairs are made.

We got back to the marina later today and I took the boat from the gas dock
to our slip, with the temperature rising to 220F during that short trip from
the gas dock to our slip (5 minutes). The boat also ran very rough during
that short trip

So.......besides replacing the impellor any other suggestions on what I
should ask the marina to do? What is causing the rough engine, especially
after having a tune up only 4 engine hours ago? Is there some internal
damage I may have done?

Single 1997 Volvo Penta 4.3L, Chevy 190 HP.

TIA for your answers.

BTW: My vacation started this afternoon (one week of it) and this was the
last thing I expected to have to deal with.