HMS Alliance - Forward Torpedo Tubes

The forward part of the submarine is taken up by four torpedo tubes and the torpedo stowage compartment with space for six reload torpedoes. The tube space is separated from the stowage compartment by two watertight doors to isolate the bow section in the event of damage or flooding through the tubes. It was through opening a tube rear door with the bow cap already open that HMS Thetis was lost on trials in Liverpool Bay in 1939. Additional safety devices were subsequently fitted to prevent this ever happening again and these can be seen on the tube rear doors in Alliance.

To see large versions of all the photographs, click on the pictures.


The forward torpedo stowage compartment and torpedo tube

The Torpedo Stowage Compartment also served as a sort of community centre, and it was here that films were shown and Church Services held on Sundays at sea. The Captain conducted these non-denominational services as a temporary, acting, unpaid parson with the off-watch crew crammed between and around the torpedoes. It was a matter of particular pride (and worth a few pints in the local pub ashore when telling the tale) for anyone getting married to have his Banns called on these occasions.


Church service in the forward torpedo stowage compartment

The 21-inch diameter torpedoes were loaded into the submarine through the circular loading hatch on portable rails and then either stowed in racks on each side of the compartment or hauled by tackles into the tubes. The Mark VIII torpedo weighed about one and a half tons and carried a 805lbs torpex explosive charge. It was the standard anti-ship torpedo and was usually fired in salvoes, spread and spaced to cover possible fire control errors and hopefully to ensure the required number of hits to sink the target. An angle could be continuously set on each torpedo gyro in its tube; the gyro followed this angle after discharge thus avoiding the drawback of older systems which had no angling gear and which necessitated the submarine itself steering the aim-off course (Director Angle or DA) along which the torpedoes had to run.


Fwd Torpedo loading hatch


A salvo of torpedos head towards their target

The Mark VIII torpedoes, powered by an engine using a mixture of compressed air and shale oil, ran out to 5000 yards at 45 knots but the Captain endeavoured to fire at an ideal range of about 1200 yards which allowed ample time for the ‘fish’ to take up their depth and course but reduced the chances of a target altering course while the torpedoes were running.

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A Mark 8 torpedo

A torpedo was initially launched by compressed air, which was not itself allowed to escape from the tube and make a telltale bubble on the surface. The weight of a torpedo surrounded by water in the tube was greater than a tube full of water alone; an automatic device not only allowed the tube to be instantly reflooded on firing but also let in a certain amount of additional water to a tank below the tube space to compensate the trim automatically.

Some of the torpedoes carried were designed for use against other submarines and could home acoustically onto any submerged target, which was emitting noise from propeller cavitation or the engines when snorting. These Mark 20 torpedoes were produced to deal with quieter targets at long range.

Mines, torpedo-shaped for discharge through the tubes, could be carried instead of, or as well as, torpedoes if required. Mine laying was slow, boring and without visible results; in shallow enemy waters it was not a popular pastime.

Three-inch or 4-inch guns were fitted on most submarines during both world wars as well as smaller anti-aircraft weapons. Alliance lost her gun when modernised but could still have been fitted with one if the need arose. As German U-boats found to their cost from 1942 onwards, the increasing threat from aircraft made it dangerous to surface for gun action in areas of high anti-submarine activity. Post-war submarines discarded guns for this reason as well as for the sake of streamlining.


The torpedo stowage compartment was also one of the escape compartments and had an escape hatch amidships. If escape ever became necessary the crew would have donned escape suits and, while the compartment was being flooded to equalise pressure and enable the hatch to be opened, they would have breathed pure air from a built-in breathing system (BIBS) whose connections can be seen overhead all around the compartment. A twill trunk could be pulled down from the hatch surround and a vent opened in the hatch itself to release the air and form a solid column of water up to the hatch. If the submarine lay on the bottom at, say, 100 feet the water would only rise to three-quarters of the way up the rest of the compartment so that the crew would have had their heads above water while waiting to climb up the ladder through the trunk.


Escape equipment located in the forward torpedo stowage compartment

The method of escape has now been greatly simplified and improved by the introduction of the Hooded Immersion Suit and escapers do not wear any kind of breathing apparatus; the old Davis Escape Sets from which escapers breathed pure oxygen were found to be dangerous because oxygen poisoning was bound to result from breathing it under pressure. Trial escapes in modern suits have safely been made from depths down to 600 feet and the suits are designed by doctors to give maximum protection particularly from cold while escapers are waiting to be picked up on the surface. An escape suit includes, thoughtfully, an outsize nappy for medical reasons as well as comfort!

Alliance did not, incidentally, carry a doctor. The Coxswain, who was fully trained in First Aid, offered free treatment from a medical chest, some of whose contents were so alarming that the crew took care to remain very, very healthy.

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The Single Escape Tower and Immersion Suit