Originally Posted by
Trim Stab
No it wouldn't. The crew in a submarine are breathing air at 1 atmosphere. The water pressure outside the submarine is 1+(x/10) atm where x is depth in m. So if donning escape breathing gear, an escapee has to be pressurised in a water-lock in a short period of time to outside pressure, then be released to swim free. That is already quite a challenge, even just down to shallow depths. Then there is then the question of what gas they would breathe. Air is only good down to about 40-50m. Most people get gas narcosis (like being drunk) at deeper than 40m, and below 60m the risk of CNS poisoning due to high oxygen partial pressure becomes impossible to manage. Hence the RN SETT tank is only 30m deep because that is the maximum depth escape is realistically possible using air as a breathing gas. From that depth you don't need the bulk and complication of scuba gear - just swim free with the submarine escape apparatus.
Worth pointing out also that SETT training in RN is carried out in warm (above 30 degree) water with good visibility - not conditions which would normally be encountered.
https://www.youtube.com/watch?v=XKNhg7PNBvc
The present system does not use compressed air but works at 1 atmosphere with a suit, tested to 170 mtrs. Compressed air even one breath leaves the victim with a serious risk of decompression sickness (DCS)and unless a chamber is very close potentially killing the survivour. A DCS medical treatment chart asks if the injured party has taken a breath of compressed gas, if not then they do not have a risk of DCS. Decompression chambers are used for diving incidents where the rate of assent is far too quick as in medical emergency or equipment failure. Maximum ascent rate for a recreational scuba diver is 18m/min with a stop of 3 min at 5m or until the air supply is nearly exhausted. Muli gas diving using various combinations of 02 and He is a totally different sport, the same as using rebreather systems.
Think of free divers down to a couple of hundred metres, present record is 214 on one breath. They enter the chamber sealed in a 1 ATM environment and end up on the surface in a 1ATM environment. Free divers descend on a sled attached to a cable and release a balloon to return to the surface. In their case the main daanger is shallow water blackout and hypoxic fitting as the remaining oxygen in the blood is consumed. In this case there is plenty of air in the suit to breathe.
https://www.youtube.com/watch?v=0voNailcOg0
This is the first part of the QED documentary about free diving and the research done at DDRC (Diving Diseases Research Centre) on people who are free divers.
SETT allows training in being able to use the escape systems, suits, lockout etc and as we learnt doing NBC drills to give confidence in the equipment.
As this continues, the hope for survival is growing less. If the worst comes to the worst, in I believe in the submariners world the crew would be forever 'On Patrol'.