The Tank
Done it three times in the sixties as we had to do it every year, I know there are a lot on here who have done it but for those who haven`t
Before doing the tank we first had to do the equivalent depth in a de-compression chamber and this was a weird experience. The most unpleasant part was during the pressurisation when the air got hot, but I think the main object of the exercise was to permanently bugger up our ears and at this it was very successful.
Then we were split into groups and issued with our gear, this was a full safety suit for one member only, and for the rest of us a life jacket and a nose clip.
First we went into the side of the tank at 30ft ducking out and rising up to the surface just by holding our breath… easy.
Then we went into the air lock at 60ft and this time we had to make sure we were breathing out all the way to the top. There are PTIs in there hovering looking for victims
100ft down in the base of the tank was a simulated submarine compartment containing an escape hatch with the standard canvas ring
After we climbed in the outer door was shut and sealed and the instructor dropped the canvas trunking down to about 3 ft above the floor and secured it with some rope.
Then came the orrible bit …suddenly water started swirling around our feet and although we knew that it should stop around waist level with air/water pressure equalised the canvas trunk under the water it was defiantly a moment that separated the men from the boys.
In the compartment we had a bibs system (emergency breathing mouthpieces) which we now used and with the water equalised at waist level the instructor ducked inside the canvas trunking and opened the hatch.
Air pressure is half the depth so at 100ft the air we were now breathing was at a pressure of about 50lbs /sq” . How free accent works is, you take a breath at a high pressure and as you ascend the air in your lungs expands, therefore as you rise to the surface you have to breath OUT all the way up.
As bodies began leaving we moved along and took the next mouthpiece then it was my turn, I ducked under the trunking rose up through the hatch.
I was immediately grabbed by a PTI who, when happy that I was breathing out, let me go and the life jacket took over.
Some panic on leaving the hatch and forget to breath out, the normal course then is a swift punch in the stomach and if that doesn’t work there is a diving bell nearby.
I rose up and could clearly see the wall markings giving the depth, all the time breathing out, then at 30ft I ran out of breath but before I knew it I was on the surface, climbing out I was told to get fell in.
The ordeal over we were then made to stand upright in a line for 10 minutes all the time a medical team walked up and down peering intently into our ears, noses and any other holes they could find.
Finally the tension was broken by a 2 ring MO asking if anyone had any discomfort.
Yes sir, came a reply in a heavy welsh accent.
“That ferkin nose clip really hurt”
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