HMs/m Tempest design and statistics

The Royal Navy submarine HMs/m TEMPEST was a 'T' Class submarine, built at Cammell Laird's base in Birkenhead, Liverpool. HMs/m TEMPEST was one of seven Group Two submarines to be built starting in 1939, having numerous modifications from the Group One submarines. In total there were 58 'T' Class, (or Triton Class - after the first submarine of this class to be built in 1935) ordered, but 53 were actually built.

HMs/m TEMPEST (pictured left) weighed over 1,422 tons on the surface, and over 1,570 tons when submerged. With an overall length of over 273 feet long and over 26 feet wide (called the 'beam'), these submarines sounds really large, but, of the 26 feet beam, 14 feet 6 inch was the pressure hull. This hull prevented the crew and equipment from being crushed to death when submerged in deep water. So really, the crew only had a minimum of 11 feet wide to live and work - then there were all the pipes, instruments and storage!

The awesome firepower carried by HMs/m TEMPEST, (and the other six in the Group Two series), included a total of 18 Mk VIII or Mk VIII** torpedoes, a Robert Whitehead design, from 11 x 21 inch tubes. Also, a 4 inch Mk XII QF (Quick Firing) gun, mounted in front of the conning tower, for the quick, surprise attack. Finally, about three or four (depending on availability) Vickers .303 gas-operated machine guns.

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Of the 11 torpedo tubes on the submarine, eight were forward facing firing tubes, six were internal of which three tubes were on the Starboard side, (on right looking down to the front of the sub), numbered 1,3,5 and three tubes on the Port side 2,4,6. A further two tubes 7 and 8, sited at the front were external in the casing above the internal tubes. Tubes 9 and 10 originally were external forward facing tubes sited either side of the conning tower, but on TEMPEST (and others) were reversed and fired stern wards (fired behind them).

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The torpedoes, of which there were a total of 18 Mk VIII or Mk VIII** design were approximately 21 inch in diameter and 21 feet long, weighing approximately 11/2 ton (1,566 Kg), were mainly a Whitehead design. There were two loading hatches for the torpedoes (one at the front and one at the back). To load the torpedoes, a special cradle was hinged down in the submarine onto which each torpedo was lowered. The torpedo was then man-handled into the special storage compartments, (just in front of the tubes), either side of the sub, using a block and tackle, until required. At the front, there were three torpedoes stored on each side of the sub, taking up valuable space, so almost everything was put on the torpedoes when at sea, especially the belongings of the crew working in that compartment!

When torpedoes are loaded onto a submarine, all the tubes are loaded first, taking up 11 torpedoes, mainly to save space and also to save time having to load one to fire, the remaining seven torpedoes are stored in the sub, including one at the back compartment. The external tubes could not be re-loaded once fired, until they return back to base or a depot ship. Hatches were lifted above the external tubes to allow the torpedoes into them.

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Vickers Photographic Archive,
Copyright Barrow Museum Service.

TEMPEST also carried a 4 inch Mk XII Quick Firing (QF) gun mounted in front of the conning tower. Similar to the one shown on the left -reproduced by kind permission of Barrow-In-Furness Submarine Association), The gun could fire about 13 shells a minute - hence 'Quick Firing'. Weighing about 2,900 lbs (1.3 ton / 1,318 Kgs), this type of gun was first introduced around 1913. After some improvements, the Mk XII was fitted to all 'T' boats. The overall length of the gun was about 13 feet with a range of about 10,500 yards, using a variety of shells available, but mainly a 35 lb High Explosion (HE) shell.

The elevation and train (turning the gun barrel left or right etc.) was done manually by one of five operators, mainly the "trainer", the other four being "breech worker"; "sightsetter"; "gunlayer" and "loader". The gun was housed in a metal shield and was built for swiftness. As soon as a target was identified, the submarine manoeuvred to a good position, (it is reported that such a position would be 1,000 - 2,000 yards aft of the targets beam was best), as soon as the sub surfaced - it's secret position was revealed, so the gun crew had to be ready to get up the hatches, bring the gun onto target, load and fire! Some reports show this action could be done within 30 seconds!

As you can see, speed was the key here. get up to the surface quick, train the gun and get the shells into the target, once the target was disabled or sunk, the gun was secured and the sub was submerged before they were spotted.

Shells ranged from HE (High Explosive) SAP (semi-armour piercing) and starshells. Each sub, including Tempest, was limited to about 100 shells in total. They were stored as close to the hatch of the gun as possible, to reduce the time bringing further shells up etc.

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Each submarine carried about three or four . 303 Lewis machine guns (for 'close work'). In the case of HMs/m TEMPEST however, she had the more stable Vickers .303 gas-operated machine gun, or also known as the 'K' Gun. A .303 Bren gun was a very useful replacement. (In later years, these were replaced with the 20mm Oerlikon and became 'THE preferred weapon.') these machine guns required two operators, one to fire and one to load the ammunition belt or feeding the belt into the gun. After use, the guns were stored below decks rather than kept above.

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STILL TO COME -
ASDICS
LIFE ON A 'T' CLASS
THE POWER-HOUSE - DIESEL AND BATTERY

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