HMS/M Thetis

In 1939, HMS/M Thetis was built as the third of the T class of submarines. She was the first submarine built on Merseyside by Cammell Laird. She was the pride of the navy, of the men who built her and the men who sailed in her. To very many, ninety nine of them, she was soon to become their tomb.

She was lost on her very first dive, on the 1st of June 1939, in Liverpool Bay, and all but four of her ships company, contractors and VIPs died with her. So close to safety, with the stern above water, the steel hull that should have protected them from the dangers of the deep, became their coffin wall.

Why did this tragedy happen? A series of bad luck and mishaps which on their own would not have been fatal, came together to make a lethal combination for all involved. On board were many civilians, technical and industrial workers from the builders yard, officers and ratings, not just from Thetis but from other ships, even catering staff: there was to be a grand buffet on board as this was to be a grand event. Thetis had almost double the number of personnel on board that she would usually have. These visitors came to Thetis to see, learn, watch, observe, test, adjust and to enjoy a new build submarine...for Thetis was on trials and on her way to her maiden dive at sea. Among the additional 50 passengers, were 26 employees of Cammell Laird, 9 other naval officers, 4 employees of Vickers Armstrong, 1 from Brown Bros and 2 from Liverpool City caterers. At the last minute the Mersey River Pilot, who had supervised Thetis's passage down the Mersey, was asked if he wanted to remain onboard for the dive and he accepted.

On her transit to the diving area Thetis was behaving slightly different to helm than one would expect, even on a new and untested new build. She was also a little too high in the water on one side when compared to the other...in other words she was not truly floating upright at the correct level...she was too light....so a proper 'trim' had not been set before leaving port. This should not have been so as all this had been calculated with tried and tested formulae that had been proved for many years in the submarine service. This calculation, a mixture of theory and practical shifting about of, and taking on of, water and pig iron ballast, to 'trim' the submarine had been done, approved and demonstrated to the Admiralty overseers at the builders yard.

As the Thetis crew closed up for her first dive, she would not, at first, go down. But suddently, she did.

No. 5 tube bow cap was open and the tube was flooded, open to the sea, while Thetis made her maiden passage out to the diving area. The rear or inner door of a torpedo is always shut when the tube is full of water. The two doors, inner and outer, are never open at the same time....except on Thetis on that day.

In the forward torpedo compartment water had gushed in through the 21 inch wide No. 5 torpedo tube that - incredibly - was open to the sea. The internal rear door of No. 5 tube had been opened at the same time as the external bow cap of the same tube was also opened. Water flooded in in a torrent overpowering all and making the closing of the hatch impossible. The impossible had happened. Both doors open on a torpedo tube while at sea. Immediately she became heavy as she filled with water forward. Pure bad luck, small design quirks of water tight door closing, decisions that would be right any other day became deadly wrong today. She went down and stayed down.

A speck of paint, or enamel, had blocked the test drain pipe tap on the tube. This was a test to see if the tube was full or empty of water. If the tube is dry, no water will run out of this pipe, if however the tube is full of water, then water will run out. But the drain was blocked so, even though the tube was full of water, none came out. The person doing the job assumed that the tube was dry and opened the rear door.

Someone at the builders yard while applying protective enamelling to the inside of this tube had allowed a drip of enamel to run, trickle, to seep into this pipe....un-noticed.

Those trapped in Thetis, which by now had her bows stuck in the mud, tried everything to break free, to rise to the surface, but nothing worked.

Four escaped, ninety nine did not. More should have but, again, did not. Some waited when they should have tried to escape earlier. Ignorance of the Davis Submarine Escape Apparatus proved a handicap, at that time submariners received little or no escape training and there were twice the number of people using up the air meant for 36 hours. Navy rescue efforts were at best confused. The lack of a practiced plan, red tape, naval politics, rank issues, confusion and sheer helplessness hampered the rescue at every corner.

So Thetis was stuck in Liverpool Bay, with her stern out of the water. With 99 people onboard. The crew succeeded in raising the stern of the submarine throughout the night of 1/2 June, so that when she was found at dawn on 2 June by the destroyer Brazen, some 18 feet of her stern were above the water.

The survivors were Captain H.P. Oram, the Captain of Thetis's flotilla; Lt. Frederick Woods, the submarine's torpedo officer; Leading Stoker Walter Arnold; and Frank Shaw, a Cammell Laird fitter.

After Arnold and Shaw had escaped, the seamen operating the chamber, by now suffering the lethal effects of carbon dioxide poisoning, made an error in the drill for working the chamber so that the upper hatch could not be opened. Another four men tried to use the chamber but were dragged out dead or dying having failed to open the upper hatch.

Salvage operations on Thetis resulted in the death of one of the divers involved in this dangerous and cold work. On August 23rd. 1939, Diver Petty Officer Henry Otho Perdue died of a severe "bend".

Sunday 3rd. September saw Thetis intentionally grounded ashore at Moelfre Bay, Anglesey. It was the same day that war was declared. Human remains that had not already been removed by the salvage team were now brought out to a decent Christian Naval Funeral, with full honours.

When the Thetis had been recovered, repaired and overhauled, she was re-commissioned as the Thunderbolt. Though the first crew of Thunderbolt joined, unsurprisingly, with some apprehension, she went on to a successful war until she was finally lost north of Sicily in March 1943.

See Thunderbolt

See also two splendid books from Avid Publications

"Thetis, The Admiralty Regrets..."

"HMS Thetis, Secrets and Scandal"