Can't afford to run gas engines in my preferred tonnage of boat, even
though gas engine boats are usually tens of thousands of dollars cheaper
at the start. Thinking about replacing gas engines or buying a boat
with.

Been through Pascoe and all that. Have been a fan of gas engines all my
life and would stick with 'em if it weren't insane at this point.
Gasoline isn't that much more expensive but diesels are simply better on
consumption.

I'm talking about pushing around a 25,000+# vessel with a planing hull
but perhaps just pushing it around at hull speed or slightly above.

Seen lots of different diesels in boats. Cummins, Detroit, Perkins,
Volvo, Hino, Yanmar, Mann, John Deere and, of course, Cat in natural and
turbo.

The major differences I understand a

2-cycle vs. 4-cycle
Natural vs. turbo
Aluminum vs. steel
Piston sleeves or not

If you were advising someone on what to look for/avoid, in either new or
used diesels, what would you say???

Thanks in advance,

jps