Heard the one about the diesel sucking air out the ship…dont buy it at all I’m afraid!.

Our subs have monitors to keep track on the air pressure in the boat and, with dielectric boats with big engines, the relative high chances of a wave washing over the snorkel and causing the diesel to suck internal air are such that I cannot imagine anyones boats NOT being fitted with a similar monitoring system. The analogy would be someone deciding to economise on a car design by ommitting the brake lights.

The other thing is that reserve air group valves are usually not more a few feet from someone who knows what they do and, again, there should be compressed air storage enough to repressurise the boats atmosphere, certainly enough to forestall hypoxia and asphyxiation very speedily to hand i.e within a very few seconds of the effects of oxygen deprivation being noticed. If nothing else everyones ears popping should have been a good indicator of an air pressure drop in the boat and actions to remedy these situations should be amongst the first lessons the crew had before they set foot aboard the boat!!!

Some people have commented, like Crobato originally, on some form of gas leak in the hull that, somehow, remained undetected while it poisoned the crew and had physiological effects that caused death so swiftly that none of the crew were able to get an SOS off. Can’t think of a substance commonly found on a boat that would fit those parameters?

Hell of a mystery now!