HMS/M Thetis was a brand spanking new submarine, the third of the then modern and new class of submarine boats – the “T” class boats. 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 so very many – ninety nine of them – she was soon to become their tomb.
On her very first dive, on June 1st, 1939, her very first venture into the element for which she had been designed and built, she died. Those with her, save four, died too. 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. Bad luck, a series of bad luck, a series of 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 builder’s yard, officers and ratings , not just from Thetis but from other ships, even catering staff: there was to be a buffet on board as this was to be a grand event. Thetis had almost double the number of souls on board than 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.
So why did she sink?
Of the mishaps which was the first one that started the chain? Which was the first domino to fall? The first one was not the one that did the fatal deed. It has never been explained as to why the external bow cap of No. 5 torpedo tube was open.
No. 5 tube was flooded – it was open to the sea, so while Thetis made her maiden passage out to the diving area her No.5 torpedo tube cap was open. A mystery as to why to this day.
However, although not good practice, it is generally not lethal. That is because 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 , ever, open at the same time – except on Thetis on that fateful day.
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. It has never been explained why.
This should not have been so as all this had been calculated with tried and tested formula that had been proved for many years in the submarine service. This calculation – a mixture of theory and practical shifting about of pig iron ballast put on the submarine as “her trim”, had been done, approved and demonstrated to the Admiralty overseers at the builder’s yard. So why? We do not know.
As she closed up for her first dive, she just would not go down. She would not dive. Then suddenly she did, her bow dropped and down she went. Her first dive was her last.
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. Immediately she became heavy as she filled with water forward. Pure bad luck, small design quirks of a water-tight door closing, decisions that would be right any other day became deadly wrong today. She went down and stayed down.
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.
A speck of paint, or rather 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. Except that at this critical instant on Thetis, this test drain pipe was blocked by a spot of enamel. So even though the tube was full of water, none came out. So the door was deemed empty and thus opened and Thetis sank.
Someone at the builder’s 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. Thetis fate was sealed. There are checks to test the efficacy of this pipe to avoid blockages but in this case…but, but…..The bow cap was open …but the trim was wrong ..but, but, many buts, few answers, dead men.
Those trapped in Thetis which by now had her bows stuck in the mud tried everything to break free, but, again too many buts, no luck, just bad luck. Even in this deadly situation Thetis could have survived, but for, and due to this and that….she did not.
Four escaped, ninety nine did not. More should have, but 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 training in “how to escape” and there were so many people using up the 36 hours of air. 36 hours for half the number of people!! Navy rescue efforts were at best confused, lack of plan, common purpose, red tape, naval politics, rank issues, confusion and sheer helplessness hampered the rescue at every corner.
Thetis could have been rescued, but for, and if had, or due to……all small errors which on their own would be a hindrance, came together in a fatal cocktail.
This extraordinary tale can be found at The Thetis Memorial Page.
But where’s the Ivens connection?
A newspaper article in The Skegness Standard in July 1939 reported how one Reverend T L Ivens, vicar of Walcot, (near Skegness, Lincolnshire) had proposed a possible solution for saving the crew. The reason why it hit the press was that his solution was one of only 3 out of over 300 which had been featured by a London Newspaper.
So, another good idea from some crack-pot vicar!