Diving the SETT (Submarine Escape training Tank)
Gren and I were lucky enough to fill some gaps on a University of Surrey trip to dive the SETT on Sunday 19th March 2006.
I have a list of places I’d like to dive and the SETT is on it because my Dad was in the Royal Navy and at one stage served with First Submarine Squadron on HMS Maidstone at Portland, and so had to train on the SETT in 1957. Admittedly we were obviously going from the top down rather than in the other direction as he had when doing buoyant emergency ascents! Gren on the other hand wanted to try out his new video camera and housing at depth so we were both happy to get the opportunity to go.
The Submarine Escape Training tank is at Fort Blockhouse (formally HMS Dolphin), in Gosport, Hampshire. It was constructed during the late 1940’s, and ran its first training course in July 1954. Apart from occasional shut-down periods for maintenance work the tank has been operational continuously since it was first commissioned, training approximately 1,500 submariners per year.
The preferred method of submarine rescue is to use a small submersible attached to the forward or aft escape hatches of the stricken sub. As these can only take around 15 people at a time and you may have as many as 150 people to rescue, this could be a time-consuming process. As a last resort, the submariner needs to involuntarily become a diver, and do a buoyant emergency ascent to the surface. Various apparatus can be used to assist with the ascent, including suits and various ascent aids. The SETT is used to practice these varying escape techniques.
The SETT is the world’s only 30 metre deep tank and is 5.5 metres wide with a balmy water temperature of 34C. What’s slightly odd is the fact that the surface is on the 10th Floor of a tower block while the bottom is pretty much at ground level. Luckily there’s a lift! Most people wore shorties or just t-shirt and shorts but I wore a full-length 5-mm wetsuit and felt fine (mind you, I can’t think of a single time when I’ve been too hot diving ﾐ even in Egypt).
We were given a health and safety briefing then a dive brief. We were to get in as buddy pairs, have a maximum bottom time of 15 minutes with the second pair getting as the first pair began their ascent and so on. We were second in, and as the water surface is just below the rim of the tank you needed to climb the ladder, swing yourself round and gently lower yourself into the water so that you didn’t displace any. Having then donned your fins and mask you begin your descent.
It’s a bit like diving in a space ship, everything is white and very well lit with depth markers at 5 metre intervals. You can see the surface clearly at every point, although you have to crane your head up, and those on the surface are given clear Perspex boxes so they can see what’s going on down below. Although wide enough across, it does give the feeling off descending down a tube as you can only fin a couple of strokes before hitting the other side.
Looking into the depths
At the bottom are the hatches the sub-mariners exit through (there are other entry points higher up at different levels), a very anatomically correct mural of mermaid(!) and a porthole. Again, that played with your senses, because you were looking into someone’s room but could see a window and the sun shining outside which was really strange when your depth gauge was measuring 27
There is little to explore so we just pootled round, looking at varying portholes, blisters, lights etc. as we began our slow ascent, passing the next pair as they descended. Reaching the surface, after a safety stop at 6 metres, we had clocked up a 24 minute dive with a maximum depth of 28.1 metres. Again, at the surface you need to stand on the ladder draining off water before carefully climbing out. All in all it was an interesting experience ﾐ you also get discounted entry to the Submarine Museum for the price of the dive – and we’re grateful to Surrey University for organizing the trip.
Gren dived the SETT to check-out his new video set-up – This is what he put together…