HMS K15: The Steam Submarine That Sank in Harbour on a Summer Night

Built on the Clyde

HMS K15 was laid down by Scotts at Greenock on 19 April 1916 and launched at the end of October 1917. She came into service in the spring of 1918, one of the later boats of the K class, and by then the class already had a reputation that no amount of fresh paint was going to fix.

The K boats were the Royal Navy's attempt to build a submarine fast enough to work with the battle fleet. To make twenty-four knots on the surface they used steam turbines and oil-fired boilers instead of diesels, which gave them the speed of a destroyer and the habits of a kettle.

A K boat was 339 feet long, displaced nearly 2,000 tons on the surface and carried eight 18-inch torpedo tubes, two 4-inch guns and a crew of 58. Before she could dive, her two funnels had to be lowered, the boilers shut down and every air intake closed, and the whole business took minutes rather than seconds.

Why anybody thought this was a good idea, and what it cost, is told in full in the history of HMS K3, the first of the class. K15's story is a smaller one, and in a way a more telling one, because nothing that happened to her had anything to do with the enemy.

Twice to the Bottom

She was commissioned under Lieutenant Commander Hubert Vaughan-Jones and joined the K boats of the Grand Fleet, whose flotillas were based on the Forth at Rosyth.

She had missed the worst night in the class's history: at the end of January 1918 two K boats had been sunk and more than a hundred men killed in a chain of collisions off May Island, and the survivors of that night were still in the flotillas when she arrived. Her crew can have had few illusions about what they had joined.

They were quickly given reasons to keep them. During her trials K15 dived bow first and out of control when her after hydroplanes failed, and went into the bottom. She came off it virtually undamaged, which in a K boat counted as a good day.

The second time was worse. In her first summer, running on the surface in a heavy sea, she took water in through the openings for her boiler room and the boilers were flooded out. With no steam she could not drive ahead, and she settled stern first on the bottom in about eighty feet of water.

Getting her back up took eight hours, because every time the pumps were started the bilge suctions choked on cotton waste, the rags used for wiping down machinery, which had washed off the deck plates into the bilges. For eight hours the crew of a 2,000-ton warship were held on the seabed by the cleaning cloths.

The class was being altered all the while. The openings in the funnel casings had been designed so that they could open both ways, a poor arrangement in a vessel that spends part of its time underwater, and the boats were modified one by one.

After the war most of them were also given a raised, flared bow, the "swan bow", to stop them burying their noses in a head sea, and K15 appears to carry it in the photograph above. None of it changed the basic problem, which was that a very long, very fast submarine with holes in its top was always going to be one mistake away from trouble.

A Celebrated Captain

By the summer of 1921 the war was long over and K15 was at Portsmouth, the home of the Submarine Service, with its headquarters across the harbour at Fort Blockhouse, later HMS Dolphin. Her captain was now Commander George Fagan Bradshaw, and he was no novice.

In March 1917, in command of the submarine G13, he had found the German minelaying submarine UC-43 off Muckle Flugga at the northern tip of Shetland and sunk her with a torpedo. All 26 of her crew were lost.

It was one of the few occasions in the First World War when a British submarine sank a U-boat, and Bradshaw was awarded the DSO for it. A man with that record could reasonably expect a good career ahead of him in submarines. K15 put an end to it.

25 June 1921

On the night of 25 June 1921 K15 was lying in the tidal basin of Portsmouth Dockyard, moored alongside the light cruiser HMS Canterbury. Most of her crew were ashore on leave, and only a small watch remained aboard. It had been a hot day.

The K boats opened and closed the vents of their main ballast tanks hydraulically, and the vents were held shut by the pressure of oil in the hydraulic system. During the heat of the day the oil had expanded.

As the evening cooled it contracted, the pressure in the system fell away, and one by one the vents began to open. Air escaped from the ballast tanks, water took its place, and K15 began, very quietly, to dive at her moorings.

The first anyone knew of it was when a member of the watch found her stern already awash. He roused the others, and they got across to Canterbury as K15 settled lower, with bubbles streaming up around her. Water reached her open hatches and poured in, and she went down alongside the cruiser in the basin.

Because she sank so slowly, and because most of her people were ashore, nobody was lost, which makes her the luckiest of the K boats that went to the bottom. Five months earlier her sister K5 had dived in the Atlantic during an exercise and never come up, with 57 men aboard.

It is hard to think of a more humiliating way for a warship to sink. She was not in action, she was not at sea, and she was not even being worked on. She was tied up in the middle of the Navy's principal dockyard, alongside another warship, and she sank because the sun had gone down.

Raised and Written Off

Salvage was quick, since she was lying in a dockyard basin rather than in open water. She was raised in about a fortnight in July 1921 and beached, but she never went to sea again.

The Navy was shrinking fast after the war, the K boats were expensive to run and widely distrusted, and there was no case for spending money on a flooded one. She lay in reserve until August 1924, when she was sold to be broken up.

The court martial that followed was less forgiving. It found that standards of attention and supervision aboard K15 had been slack, and Bradshaw was told that he would not be given command of a submarine again.

That seems a hard ending for the man who had sunk UC-43, but the court's point was a fair one: hydraulic systems do lose pressure, and the purpose of a watch aboard a submarine in harbour is to notice. Somebody should have been looking at the gauges long before somebody else noticed the stern was wet.

The End of the Steam Boats

Her loss came at the end of a run of accidents that had made the class a byword in the Navy. The sailors' nickname for them was "Kalamity".

One more was completed after the war to an improved design, K26, and the idea of a big submarine to accompany the fleet surfaced again in HMS X1, which was driven by diesels and had its own troubles. By the early 1930s the K boats were all gone, and the Royal Navy never built another steam-driven submarine until it found a better way to boil water, inside a nuclear reactor.

The photograph at the top of this page was taken by Surgeon Oscar Parkes, a naval doctor who became one of the great photographers and historians of the Navy's ships, at some point between 1918 and 1921. It shows K15 on a still day with men out on her bow and around her guns, the funnels that were the whole reason for her existence standing up behind them.

It is a fine picture of a handsome ship. She looks fast, and she was. She also looks like a destroyer, which in the end was the whole trouble.