Tom:

What you say for simple, non turbocharged, non common rail diesels is mostly, maybe all true.

The more sophisticated engines, mostly on power boats, require much more maintenance. The fuel has to be pristine in a common rail engine. And with an intercooled turbocharger and specifically a seawater cooled one, it takes disassembly, cleaning, lubing, reassembly and testing every 3-5 years.

Also such power boat diesels sometimes are installed with poorly designed exhaust systems that will let sea water back up into the engine.

So it isn't all that easy with a high output diesel. If you don't do all of that stuff right, you can trash your engine.

David