I am number three on an attack line consisting of 2.5 inch cotton covered hose pressurized to something in excess of 130 p.s.i. At these pressures the hose is as stiff as a tube of steel. You have to throw your entire weight into it to bend it around alley corners, or force it to descend through a hatchway to reach the deck below.

Somewhere in the murk ahead of me are numbers one and two. I cannot see them but I know they are up there. My job is to feed them hose. Somewhere to my rear is number four. It is his job to feed me with hose. All of us on the team are connected by this inflexible fat boa of canvas water pipe. It is our lifeline to safety. In the smoke you cannot see your hand before your face. The other team members are invisible. Only the fat snake of hose connects us. Protects us. Guides us out to a safe return home.

All of us are masked up in Chemox gear. Chemox is a chemical re-breather originally developed for mine rescue. It consists of a chemical cartridge the size of a fat book. You insert the cartridge in the Chemox unit, a copper seal is pierced, the chemical crystals now form part of a re-breather pathway that starts with your lungs. Your exhaust air is trapped and forced into a tube which leads it into the chemical cartridge. Moisture in your breath reacts with the crystals to absorb CO2 and release O2, the gas upon which all life depends.

The generated gas is the product of an exothermic reaction. It is hot when it exits the cartridge, too hot to be breathed. To cool it, the gas is discharged into a pair of external lungs, a pair of black canvas bags that sit outboard of your true lungs and which mimic their shape in rubberized canvas. The produced oxygen enters the right lung and cools, is then fed into the left lung for further cooling, and finally feeds into your face mask, and is made available for you to inhale. Your breathing system is a closed circuit. You are re-breathing the same volume of air over, and over again. With two critical differences. Some portion of the exhaust CO2 is scrubbed from the air stream, scavenged by crystals within the cartridge. Your body is removing oxygen from this air stream. Additional make-up oxygen is being generated at chest level and is being added into the air stream, to keep you alive.

The overall effect is the same as placing a plastic bag over your head. The plastic bag creates a barrier. It seals out the world. The result is a fixed closed system. A system in which you cannot long survive as you will deplete the available oxygen and be overcome by the ever increasing levels of CO2. Add an oxygen generator cartridge into this closed loop, replace the plastic bag film with something a little more sturdy, add a face piece and a few valves et voila You have a life support system guaranteed to keep you alive for one full hour.

When fighting a shipboard fire, you cannot see shit. Your eyes are protected by a transparent face mask. The face plate is contained within a flexible soft rubber surround that mates with your skin to create an air tight seal. It must be airtight. The products of combustion are toxic. In a fire you face three key problems:

Problem 1 – Oxygen Supply

Maintaining a constant supply of breathable, oxygen rich air, is critical. The fire will try and suck all available oxygen away from you. The life of the fire is as dependent on an oxygen supply as you are. It is a case of its life, or yours. The fire wants to win this battle.

Problem 2 – Combustion By-Products

You must protect yourself from an atmosphere filled with toxic combustion by-products. Few people people in fires die from the flames. Many die from attempting to survive in an oxygen deficient atmosphere. Most die from breathing combustion by-products, toxic gases such as phosgene. Five minutes exposure to phosgene at a concentration of 50 parts per million will kill.

Problem 3 – Finding the Fire

It sounds like a joke but unfortunately it is not. In a shipboard fire, three quarters of the battle comes from just finding the fire. Ships are composed of hundreds of steel compartments. The steel does not burn but the contents of the compartment does. The fire requires oxygen to live. As it burns, and consumes oxygen, the fire acts to suppress itself. As it suffocates, the fire emits thick clouds of smoke and these dark clouds make the fire near impossible to find.

So there we were, the four of us below decks, enveloped in a black cloud of smoke, playing hide and seek with a fire which we hoped was somewhere ahead of us and not to our rear, where it threatened our lifeline to safety. To find a shipboard fire you must stumble about in darkness, searching for signs of heated steel. Steel too hot to touch. Heat which begins to melt your boots to the deck. Heat like a physical wall that smashes into you, and from which you recoil in terror.

Four men and a hose. It sounds like a Jerome K. Jerome novel. We bump our way forward, a blind centipede testing its way in the murk, searching for danger, feeling for heat. Number one man is the nozzle man. He carries a 35 pound bronze Rockwell nozzle which sits fixed on the end of the engorged canvas boa. We are not yet running water. We have nothing to extinguish. We have not yet found the fire. As soon as we run water we are creating ship stability problems. We continue to stumble forward, clutching the hose line, hauling it with us into the depths.

There is a noise. A shape emerges from ahead of me, a shape with the speed and force of an express train. The shape knocks me to the deck. In a state of shock I pull myself to my feet trying to determine what just happened. I realize one of the men forward of me has panicked. Unable to handle the claustrophobia of being bottled up below decks, with not even your own hands being visible, he has bolted. Since he can see nothing, he could not see me. He just barrelled right through me.

I am making these observations when there comes a second noise. A second shape emerges from ahead of me at express train speed and again knocks me to the deck. The shape then steps on my back as it races away into the darkness. This is a problem. A big problem.

The Chemox contains external canvas lungs. These lungs are exposed. Any pressure on these lungs flattens them and expels their contents. The hot gas is forced into the face piece which will immediately over-pressure. The over-pressure will break the seal between skin and soft rubber. Precious oxygen will vent to the outside atmosphere. Your oxygen is lost. A second ago you were being kept alive by a marvellous Rube-Goldberg mechanism of canvas and metal intended to sustain your life. In a fraction of a second, key components of this system have been eliminated. The prior life support system is now no different from a sealed plastic bag fixed over your head.

You are now in a fire. You have no air. And seconds to live.