How many hours on a boat engine is too many?

Engine hours are meaningful but context-dependent. A well-maintained inboard engine can last 1,500-2,500 hours. Outboards and sterndrives in the 300-800 hour range are common on boats 5-15 years old. High hours are not automatically disqualifying — a 1,200-hour boat that has been serviced annually is often a better buy than a 400-hour boat that was neglected. Always request service records and do a compression test.