Bob Field's Story - Page 2 of 7

 

Then the first diver went down to clean the trenches of various pieces of garbage and seaweed that had been deposited by the tide during the night, and to attach the air line from the air compressor to the airlift. This was the time that our peace and quiet on board was well and truly shattered when the Atlas Copco road drill air compressor was started up. Taking up about 1/3 of the after deck on the Roger Grenville, the large monsters' noise dominated our lives for the rest of the day. It was quite deafening close up, and the only relatively quiet place was up the sharp end of the boat (or to go diving).

Whenever a diver was down on the site, there was always a reserve diver fully kitted up, sitting on the stern of the boat ready for an emergency. It was THE most boring job on the boat, especially in that heat-wave summer, with no shelter from the sun or wind, but nevertheless an essential job.

Although sport-diving rules stated that diving should always be done in pairs (at the least). This was working diving, and because of the generally very poor visibility underwater, and the proliferation of lines and pipes around the site, it was much safer to work alone on the seabed. Another diver in the same area stirred up the mud, and reduced the visibility to zero.

Mary Rose divers wore the minimum of equipment necessary, to avoid getting caught up in the ropes etc around the site. Wet-suit, mask, fins, weight belt, air cylinder, regulator, life jacket and most important of all, a sharp knife.

The Royal Navy dive tables recommended a no-stop time at a depth of 60 ft of 84 minutes in a 24 hour period, so anyone exceeding their combined no-stop time during the day had to hang onto a shot line under the rear of the boat for seemingly ages, until they were considered out of decompression danger.

So obviously the log keeper was an important safety factor, especially in ensuring the dive times were accurately recorded. Even though the Royal Navy decompression chamber was quickly accessible by using the marine radio to call the Portsmouth Harbour radio station, nobody ever wanted the experience of using it.

The safety precautions were, a reserve diver, an air cylinder and regulator on the sea-bed by the 48 frame, the 10 ft. AVON inflatable, the Q17 fiberglass run-about, and marine radio. Barely adequate by any standards, but we were amateurs, with only just enough sponsorship money to keep the project going.

After the second diver had surfaced, the diving cylinder air compressor was started up. This was a single cylinder diesel high pressure compressor, which was very temperamental to start. The sequence was to squirt ether into the intake, and swing the starting handle. Sometimes the motor started first time, usually it didn't, occasionally the motor would back-fire and the starting handle would fly back. I still have a scar on my knee from the time it hit me.

The cylinders would be charged up, one at a time, to around 2,500 psi, which could take up to 20 minutes They were always kept in a tank of water while being charged, to keep their temperature down, as charging always heated them up quite significantly, so when they cooled down the air pressure inside would reduce, and therefore the quantity of air would also reduce. Then they would be stored on the rear deck ready for use.

Whoever was in charge of the cylinder charging had to constantly watch the pressure gauge to ensure cylinders didn't over-charge, and also to be ready for when an o-ring blew with a bang, which always woke people up nearby.

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