Whilst trawling, the engineer on watch noticed the main engine surging with smoky exhaust. Further investigation revealed a flooded engine room and the main engine three-quarters submerged. The bilge alarm had not activated. Flooding was progressive and the crew had to abandon the trawler. Why did it happen? The exact cause of the flooding could not be determined but failure of an expansion coupling due to excessive stress or a hole/crack due to fatigue failure, erosion, corrosion and galvanic corrosion are pragmatic possibilities. Furthermore, the bilge alarm failed to activate and the seawater suction valves were immediately submerged and hence inaccessible. What can we learn? Bilge alarms should be tested at least on a daily basis. Fitting of extended spindles on seawater suction valves may avoid inaccessibility of valves and loss of control of seawater ingress