There are many relatively happy Volvo engine owners, and due to good marketing and pricing, are being used in many new boat models.
However, beg to differ HiDHo, from my personal experience, I would never own another (Volvo). Poor customer support, extreme difficulty accessing parts (even when only 4-5 years old), some mechanics would not work on it, and I also found parts to be expensive compared to other manufacturers. My engine, just after warranty (ended by time (years) not engine hours) experienced a total failure of the lower end due to a connecting rod cap (nut) not having been properly torgued from the factory. This finding was determined by a metallugical engineer who specializes in failure analysis, the insurance adjustor, and the repair mechanic. Each came to the same conclusion independently. Volvo blamed me for any number of things I "could" have done wrong (but in fact did not do) as to being the cause without even taking the time to investigate the issue. However, to be fair, after many hours of back and forth, me presenting several reports and all of the evidence, Volvo finally agree to pay my insurance deductible and let my insurance company pay for the rest.
Just my experience (oh, and by the way, a couple of other local owners of the same engine experienced similar failures). Others may have had different experiences with Volvo.
I would look at engines where parts are available like Ford Leman, Cummins, etc. even Yanmar.
Can we please note the vintage of the engines we're talking about. What is being said may not reflect experiences during other periods.