Well that fall into the "picking wrong boat" world. My sailboat has removable cover front and back that gives 355 degree access to front/back/sides of the engine. I know nothing after trawler exhaust systems, but my sailboat engine has 3651 hours on it and has never had an exhaust problem, not even a fouled elbow. That is much more than what I see on most trawlers.
Lets try to stay with reasons to consider changing to a trawler and not sailboat trashing please.
Wasn't intended as sailboat or sailor bashing. The previous posts touched on concern about failure of diesel engine and having a sail as backup. I spent 3 seasons doing every trawlerfest where I presented "Trawler Buying 101." Many sailors curious about trawlers expressed concerns about diesels in general, singles especially. Many (most?) engine installations in sailboats ive seen in the 40-foot range are not great.
Comparing reliability of a difficult to service diesel to one that was installed properly and relatively easy to service is a big difference. That's not bashing anyone or any boat. Just the way it works. In my opinion, sailors often (not always) do not understand the difference because they don't have context so they assume it's a diesel engine problem not realizing the same engine in an accessible engine bay would be much more likely to be regularly serviced.....and wouldn't strand them.
Sailboat engines are often (not always) installed below waterline. If the exhaust system isn't properly designed
for all angles of heel, engines will drown. Unfortunately, an incorrectly installed engine can go years or decades and not drown itself. Then either mix of sea state or loading becomes a straw that tips the scales into flooding if engine. Easy to assume the engine failed. Or failure to service impellor leads to leaking head gasket - easy to blame the engine, not a raw water pump buried and difficult to service. Or maybe the engine is accessible but only when you offload spare anchors, sail bags, etc. You get the idea.
I'll say it again though: doesn't mean all sailboats suffer from poor service access and poor installation. And doesn't mean all trawlers are perfect or even good or that all trawler owners setvice their engines regularly. But it does mean that sailors are mistaken if they judge diesel reliability based on their typical experience with diesels and in my experience with a few thousand collective attendees in my TrawlerFest seminars, many sailors (not all) do just that. I'll also reiterate that a single diesel - which I cruise - has a legitimate concern about redundancy. Different topic and I perceive the risk as manageable, but suffice to say some sort of backup is tough to fully argue against.
If you're a fan of Wind Hippie Sailing YouTube (very crunchy off grid cruiser), she just replaced her engine due to exhaust issues. There are a few recent threads on CF that are similar. In the 70s and 80s, Perkins, the dominant engine of the day, developed a reputation for sunshine seeking connecting rods. Engine was actually fine. Install was not. If you don't know the difference and/or don't know the problems are solvable, well, would naturally make a person question reliability of a diesel gun-shy about a powerboat.
Absolutely no offense meant. Just the nature of the beast with many (not all) sailboats.
Peter