Royal Navy. 


'T' Class Submarines.

J X113661 Chief Petty Officer T.G.M. Campbell - 1940's


Before the outbreak of World War 2, a list of new submarines required by the Royal Navy was produced.  The first to be built in 1935 would be called Triton; and so became known as the "Triton Class" or "T Class" submarine.  It was this class of submarine that the Royal Navy decided all submarines would have names rather than numbers.  They were built in three groups:

Group One
1935 - Triton (Vickers Armstrong in Barrow-in-Furness)
1936 - Thetis (later to be re-named Thunderbolt); Trident (Cammell Laird in Birkenhead), Triumph (Vickers Armstrong), Tribune (Scotts ).
1937 - Taku (Cammell Laird), Thistle; Tarpon, Triad; Truant (Vickers Armstrong), Tuna (Scotts  in Greenock), Tigris (Chatham Dockyard).
1938 - Tetrarch (Vickers Armstrong), Torbay (Chatham Dockyard), Talisman (Cammell Laird).

With war imminent, a revised list of submarines was slightly changed to read:

Group Two
1939 - Trusty; Turbulent (Vickers Armstrong), Thrasher; Thorn; Tempest (Cammell Laird), Traveller; Trooper (Scotts).

Group Three
1940 - P311 [this submarine was lost in 1943 before the name of Tutankhamen was formally allocated] Trespasser; Taurus; Tactician; Truculent; Templar; Tally-Ho; Tantalus; Tantivy (Vickers Armstrong),.
1941 - Tradewind; Trenchant (Chatham Dockyard), Thule; Tudor (Devonport Dockyard), Tireless; Token (Portsmouth Dockyard), Telemachus; Talent (to be re-named Zwaardvis** ); Terrapin; Thorough; Tiptoe; Trump; Taciturn; Tapir; Tarn (to be re-named Tijgerhaai*** ); Teredo; Talent [this was ex Tasman] (Vickers Armstrong).
1942 - Totem; Truncheon (Devonport Dockyard), Turpin; Thermopylae (Chatham Dockyard), Theban*; Threat* (Vickers Armstrong), Thor*; Tiara* (Portsmouth Dockyard), Tabard; Talent II* (Scotts).

* = Submarine was cancelled.  
** = Zwaardvis {Swordfish} & *** = Tijgerhaai {Tigershark} built for the Royal Netherlands Navy. 


The first batch of T boats (built between 1935/38) had riveted hulls, some of the second batches had welded hulls and final batches were all welded (which helped the builders construct them quicker). There were a total of eleven torpedo tubes fitted, of which three were external, so these were loaded when docked and fired only once.  The tubes were - at the front (forward) eight internal tubes - four each side. Looking to the front of the sub, right side is STARBOARD, tubes were numbered even (2,4,6) and left side is PORT, tubes were numbered odd (1,3,5) along with two further tubes above in the 'bulbous casing, numbered 7 and 8.

To improve the 'punch' of a T boat, two external torpedo tubes were mounted on the deck, either side of the conning tower, angled outwards by about seven degrees - so as not to catch itself when a torpedo was fired.  To compensate for the angle, torpedoes were fitted with a compensation device to make the torpedo run straight ahead after firing.  These were number 9 and 10.  The 11th tube was sited at the back (stern). These were really powerfully armed (for that era) with eight 21-inch bow external tubes and two forward on deck, they were to write epic chapters in the history of the Command.  Their endurance was increased from 6,900 to 11,000 miles by the conversion of No's 3 and 5 ballast tanks to carry fuel.

Although the overall size of a T boat was over 270 feet (over 82m), in length, and 26 feet 6 inches wide (over 8m), the actual room inside the circular pressurised hull (this protected the crew from outside water pressure when diving at 200 - 300 feet which could otherwise crush the submarine), was only 16 feet in diameter (nearly 5m).  This was divided into six separate compartments by means of watertight bulkheads.

T Class submarine layoutApart from an area over the engine room, (called a 'soft patch') there were six openings into a T boat, from forward to aft they were: forward escape hatch, torpedo loading hatch, gun tower, conning tower, engine room hatch and aft escape hatch.

Inside the pressurised hull, it was home to 68 crew, spread throughout the sub in their own compartments.  From forward to aft, the first compartment was the six internal torpedo tubes (all loaded and ready), and three torpedoes each side stored in their racks.  Going back through the 2nd bulkhead was the crew's accommodation (except for the Captain and stokers) and messes.

At the end of the messes and through the third bulkhead was the control room - the heart of the submarine.  The control room would house the two periscopes - the large normal periscope and the smaller attack periscope, the attack instruments, gyro-compass, ASDIC listening posts, hydroplane and helmsman posts and the "Blowing Panel.";  A ladder went up to the conning tower and bridge, the galley was at the end of the control room, along with the communication room.  Access to the gun turret was also from here.  

Through the fourth bulkhead was the engine room and motor room, each containing two diesel engines and two electric motors.  The fifth and last bulkhead was where the stokers had their mess and machinery area for steering the submarine. This was also where the aft internal torpedo tube was, together with torpedo storage.

With space at a premium, life became somewhat cramped, some crew members would not know the full compliment as each were busy within their own 'confines.'  One can only imagine what life was like aboard, operating on one's own, most  times desolate beneath the sea - depending on each other and it's resources.  It is easy to see therefore once a T boat was in tropical waters, it was 'normal' to collect over 40 gallons of water, due to condensation, (especially in the engine room), in a 24 hour period.

To help reduce condensation, air-conditioning units were installed taking air through a cooling and drying plant before going through the normal ventilation pipes.  There were no doctors on board, the knowledge coming from the crew members 'picked up' along the way, although the majority of T boat commanding officers and coxswain's had a  very brief training course in medical ailments etc.  The emergency kit (First Aid) contained average drugs, antiseptics, together with some 'basic instruments' and an instruction book.  Consequently, any cuts, blisters, boils etc, rapidly became infected within the submarine (after all you cannot spring clean a sub in wartime), together with stale air, diesel / battery fumes , bugs etc, it is no wonder a submariner became ill very quickly!

According to the book entitled "Submarine Command - A Pictorial History" by Reginald Longstaff,  "In a submerged submarine, the crew can breathe the same air for a number of hours. Normal air contains some 78 per cent nitrogen, 21 per cent oxygen and minute traces of carbon dioxide. Normal exhaled air consists of 80 per cent nitrogen, 16 per cent oxygen and about 4 per cent carbon dioxide. Long after it became impossible to light a match through lack of oxygen, a human could still work and think. After 15 hours there could be stress, and after 24 hours each human would virtually be surrounded b a 'halo' of foul air. Chemical canisters could absorb the carbon dioxide and oxygen candles could - to a certain extent - replace the lack of oxygen. The most dangerous gas was hydrogen, discharged when a electric battery was charging or discharging. The most careful ventilation was often insufficient to prevent small pockets of the gas collecting in corners, where a tiny spark or lighted match could cause a disastrous explosion."

The T boats main machinery was the diesel engines for surface propulsion, and electric motors when submerged.  each yard building T boats installed 'their' preferred make of engine.  Vickers built boats used a Vickers engine; Royal Dockyards built boats used Admiralty engines; Cammell Laird  built boats used Swiss made Sulzer engines; and Scotts  built boats used  German super-charged MAN engines ( which was later changed to Admiralty engines - for obvious reasons!)

The batteries were enormous, each consisting of 336 cells, each cell weighing over half a ton (859 Kg).  At battle stations, about five tons (6589 Kg) of distilled water could be used to top up the cells.  Fully charged, the battery could go for 48 hours at 2 knots, a top speed of 9 knots would last for an hour!  The batteries would be sited under the control room, with gratings throughout the sub for access and maintenance.4 inch gun on HMs/m Thrasher

In addition to the torpedo fire-power, there was a 4 inch gun mounted on top next to the conning tower,  This mainly for protection when unable to dive, or for a surprise attack - similar to the one shown on the right   The gun was sited inside a metal housing (which had no protection for the crew against gunfire because of the weight!) with large holes around the bottom for quick drainage of water.

A steel 'catwalk' ran the entire length of the boat and was full of holes like a colander, to minimize resistance to the sea when submerging. The bridge and gun casing were not armoured and were free-flooding, and the only access to them was through the lower and upper hatches in the conning-tower. Quite a lot of metal was brass so as to avoid magnetic interference with the compass. On either side of the pressure hull were the main ballast tanks which filled completely when submerging, and there were trimming tanks throughout the entire length of the submarine. Compressed air could be forced in to drive out the water when the submarine wanted to surface.

After the war ended, those remaining were to be modernised, but the riveted hulls of some proved a disadvantage and only five were streamlined. These were also refitted with six bow tubes only, and given a modern sonar and a fin-type conning-tower. They were Tapir, Tireless, Talent, Teredo, and Token.

Between 1950 and 1956, eight of the welded-hull type were completely rebuilt, with hulls cut in two and lengthened. Improved diesel-electric propulsion was also fitted giving a submerged speed of 15 knots maximum. Modern noise reduction techniques were incorporated, new sensors were added, and they were streamlined and given a fin-type conning-tower. The eight were: Tabard, Trump, Truncheon, Tiptoe, Taciturn, Thermopylae, Totem and Turpin.



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