|©1997 - Ian W Hillbeck|
A fresh look at the Five Streamlined 'T' class submarines of the early 1950's
Compiled by P D Hulme with thanks to John Eade and Ian Buxton for review and advice. For the précis of relevant RNSM archives, thanks to Archivist George Malcomson.
THE 'T' CLASS BOATS SELECTED FOR STREAMLINING
A frequently published commentary on 'Streamlined T class' by submarine authors, (Ref 2,3,10 & 12) is best described in Paul Kemp's definitive book - "The 'T' class Submarine", Chapter 10, where following his detailed description of the 'T' class 'Conversion' (hull extension), he goes on to say:
This is factually incorrect if the various available databases are to be considered reliable (Ref 1, 2, 3 & 4 & 18), as it is shown that the latter three were not "old nor riveted", the TEREDO being the last T class submarine built by Vickers Armstrong.
The TIRELESS and TOKEN launched March 1943, were built at Her Majesty's Dockyard Portsmouth, while the TAPIR Aug 1944. TALENT Feb 1945 and TEREDO April 1945 were all Vickers-Armstrong boats. It should also be noted that while both TIRELESS and TOKEN were welded/riveted, their completion had been delayed by other priorities at Her Majesty's Dockyard Portsmouth, so they were newer boats of an older construction when commissioned.
Ackermann (Ref 1) states that the TIPTOE, later a conversion, was the first all-welded T boat built at Vickers Armstrong. Ackermann, in some detail abbreviated here also states that the decrease in pressure hull weight due the welding process allowed an increase in pressure hull plate from 3/4 inch to 7/8 inch, increasing the safe maximum diving depth from 300 feet to 350 feet.
It is conceivable that as the first boat "Streamlined" TIRELESS was indeed riveted/welded, an incorrect assumption was made about the rest.
SUBMARINE EVENTS of the TIMES
There is no reason to doubt Paul Kemp's dates for the streamlining of the 'T' class, obtained from the Royal Naval Submarine Museum Archives (Ref 5) and it is useful to review where the Royal Navy stood in 1950 when the decision was made to proceed with the streamlining at the same time as the first two T class were receiving the more extensive and expensive 'Conversion'. A list of significant events follows:
No archival information is available (to the author) as to why FOSM decided in 1950 to commence the streamlining of five T class. The reasons are not immediately obvious if the significant changes that were required to streamline the SERAPH are considered. The 1944 conversion of this boat into a non-operational ASW target (Ref 1, 2 & 6), involved all torpedo apertures blanked, one third of the free flood apertures blanked, the forward periscope and radar mast removed, stern external tube, a small closed-in streamlined bridge, the existing main motors rated to give 13% more power, and T class propellers fitted, with many other smaller alterations. Higher capacity cells were fitted, 5350 Ah from 4750 Ah. A 12.6% increase.
The gain in short term submerged speed was significant, SERAPH achieving 12.52 knots at 411 RPM and 1647 BHP compared with 8.82 kts at 406 rpm and 1460 bhp obtained by an unconverted sister submarine SAHIB, on First of Class Trials. The endurance of the SERAPH was 15 minutes, for SAHIB endurance is not stated.
Note FOSM, Admiral Creasey's comment on SERAPH in December 4th 1944 responding to Ben Bryant Captain 7th Submarine Flotilla, apparently made shortly after his office would have likely received her September re-commissions trials report (Appendix A). There is little doubt FOSM thought the SERAPH streamlining a success as six of her sisters were later so modified and served the Royal Navy well over the years.
The comparison tests between the streamlined TIRELESS and the unmodified TUDOR show a much lower speed gain 9.5 knots compared to 8.1 knots (Ref 5). An increase of 17.2%. It would preferable to be able scrutinise the actual trial documents but they are not available (to the author). It is useful to know that typically, at these sorts of speeds, trial data speeds at periscope depth are about one knot slower than at 90 feet. The TIRELESS/TUDOR trials were at periscope depth.
Apparently no propulsion alterations took place on the streamlined 'T's apart from an 23% increase in battery capacity made by installing new cell types in the same battery tanks (Ref 5). The new cells could well have been the high capacity cells being fitted in the conversions, 5350 AH to 6560 AH, plus 22.6%.
It seems likely that the increased battery capacity was more intended for endurance than a very modest increase in short term speed in addition to that provided by the streamlining. I suggest that by this time it was appreciated that streamlining brought quietness and there was yard capacity to carry for the relatively modest external work. A minor point - these would be the first modern, in appearance, operational submarines in the Royal Navy and make a good impression on ship visits.
Motor Room photographs show the replacement of the rather old fashioned and bulky meters with modern style instruments, else the switchboards appear to be unchanged.
One thing is clear, the more expansive programme of the eight submarines the T (Conversion) Class, was not limited by lack of all welded boats, more likely it was simply that when the eighth and final converted submarine TRUMP, was complete in mid 1956, the first of the brand new PORPOISE class would be appearing in 1958 (Ref 5).
Though other riveted/welded T class submarines were available and eight of these remained in service until the early sixties, the streamline programme was limited to five submarines - the original proposal documents are not available (to the author), though I believe it is safe to say a limited role as a fast ASW target was not envisaged with several 'S' class boat available for more of the successful SERAPH modifications, if required.
The commencement in 1955 of the so called 'modernisation' programme of the 'A' class began with the ARTFUL. (Ref 1, 2 & 10). The changes no doubt improved these submarines at a modest cost and the only question is why it took so long to start the programme. The AMPHION for instance, leaving the yard after a major refit in 1953 still with her gun mounted with shield, looking much as she did on the day she was first commissioned about eight years earlier.
The programme included all but one of the 'A' class Fleet - 14 boats in all - still with folding snort masts, with a later modification to eight boats being fitted with telescopic snort masts. The programme was completed in the early 1960's. Pre-modernisation maximum submerged speed was 8 knots and a maximum of 10 knots, post-modernisation with new cells (Ref 1, 10 & 11). In terms of the hull and propulsion power, this modification appears to have been basically no more than was done to the Streamlined 'T' class but applying lessons learnt in the streamlining and conversion of the 'T' boats.
It is notable that all these 'Streamlined' 'T' and 'Modernised' 'A' boats had the desirable 'top of the fin' conning positions, unlike the first six converted 'T' class.
The compartment space remained as-built in the Streamlined 'T' boats. In the case of the Conversions, all with 14 feet added to the Engine Room, the compartment space remained the same from the Engine Room/Control Room bulkhead forward apart from the last four conversions where 3.5 feet was added to the after end of the Control Room.
Over the years it is clear the external appearance of the various streamlined 'T' boats varied in relatively minor ways, but remained substantially the same in principle.
SUBMARINE versus SUBMARINE
Admiralty Policy Statement 1948: "The primary task of our submarine fleet is to hunt and kill other submarines" Royal Naval Submarine Museum archive A1997/1
Miller (Ref 12) in his brief reference to the Streamlined 'T' suggests in passing that they were the Royal Navy equivalent of the US Navy Snorkel conversions. (Appendix E). As all the T class were by 1950 fitted with snort this does not seem a particularly good comparison. A more interesting comparison could be made to the US Navy Hunter Killer conversions (Appendix E) and the new-build K class. These were slow streamlined boats fitted in the bow with a US copy of the XXI long range passive sonar BQR-4. The main proponent of this use of the submarine was the influential Admiral Momsen and a special unit was set up to pursue the use of the submarine in the ASW role (Ref 8).
It is not unreasonable to postulate that the five streamlined 'T' class may well have been intended for the submarine versus submarine role similar to the US Navy SSK (Appendix E, Ref 8). However there does not appear to have been a Royal Navy submarine ASDIC available similar to the very sensitive passive US Navy BQR-4 for any Royal Navy submarine in the early fifties.
In view of the close relationship between the US Navy and Royal Navy, it is surprising the Royal Navy did not obtain a supply of US Navy submarine sonars like the BQR-4. though this may be explained by not being able to fit these large arrays on existing Royal Navy submarine or more importantly, the performance of the listening qualities of the existing Royal Navy ASDIC sets may well have been as good as the German derived US sets (Appendix D).
While there appears to have been an extensive Royal Navy ASDIC research programme, the installation of new sets into the submarine fleet was slow and, WWII "searchlight" type sets, the 129/138 sets and their improved versions 169/168, remained the basic fit for all Royal Navy submarine until the later part of the 1950's.
As for weapons, Mk VIII remained the standard torpedo. The Mk 20(S) homing torpedo did not became available until about 1955 so it is reasonable to assume the Royal Navy submarine branch in 1950 anticipated being able to carry out its designated Submarine vs Submarine role employing the same equipment that was used in WWII. There are reports that the Mk 20(S) was not a success and as is well known the reliable pre-war Mk 8 continued as the standard Royal Navy submarine torpedo until well into the eighties.
Mk II electric torpedo (Appendix C), was still considered a standard weapon for submarines in 1948 but this 1944 electrically powered torpedo saw little if any war service and does not appear to have been popular in the submarine branch.
In all these historical naval electronic matters, it is useful to recall the silicon transistor first came on the market in 1954 and the first simple silicon chips in 1960.
Regarding the special noise reduction of the US Navy Hunter Killers (Appendix E), at this time all Royal Navy submarines, on re-commissioning following refit, passed through the sound range at Loch Goil to ensure all machinery noise was within the accepted limits. Sound reducing mounts were commonly used for machinery required while dived in silent routine.
From the Royal Naval Submarine Museum archives - Captain B W Taylor DSC Royal Navy, C of S to FOSM - transcript of secret lecture to Senior officers' Technical Course 6 Feb 1951, where the streamline ''T' class is referred to simply as "cleaned-up". Archive A 1997/88. I interpret this as meaning cleaned-up in regard to self noise.
One thing however is certain, the planning of the streamlined 'T' boats in about 1950, came at a time when the submarine versus submarine role was considered vitally important by the Royal Navy and the only operational boats available to carry out the role were the A's, T's, Streamlined T's, Converted T's (first pair ready for service by early 1952 and 8 by 1956) perhaps some S boats, until 1958 when the new Porpoise class finally started to appear. Ordered 1951, laid down 1955 (Ref 10, Appendix G & H)
From 1945 to 1958, more than twice as long a period as WWII with the nation under a perceived constant threat from Soviet submarines, increasing in number every year.
More research is required the operational history of the streamlined 'T' boats in the fifties, anecdotal or official and I would be pleased to receive any comments or suggestions. The individual Ships Books are likely to be held at the National Maritime Museum - well out of my reach!
Extracts from correspondence in the archives of the Royal Navy Submarine Museum
A letter from Ben Bryant Captain 7th Submarine Flotilla dated 19 November 1944 (A1944/12) The subject is Future of Submarine Design and his closing statement reads:
FOSM Admiral Creasey replies in a letter dated 3rd December 1944 (same archive file)
Interestingly in another letter from FOSM dated 12 December 1944 (same archive file) It states:
The subject of Future Submarine Design was discussed at a meeting in Northways on the 11th January 1945. One of the outcomes of this meeting was highlighted in a letter from FOSM to the Admiralty dated 19th January 1945 (A1944/12)
There was also the point that FOSM had stated that - "lessons would be learned from both German and American designs on completion of the war."
It is reasonable to assume that this general statement reflects the Admiralty thinking that eventually brought about the proposals in 1947 by the DNC (Ref 5) that led to the 'T' class Submarine Conversion - Draft Staff Requirement - FOSM letter 20th May 1948 and similar unsighted documents regarding the new build PORPOISE class.
And that the approval sought in the last sentence was gained and resulted in the emergence of the SCOTSMAN, converted to a fast trial and experimental submarine in mid 1948. The S class hull with the saddle tanks removed and new smaller tanks fitted lower down the hull, approached the shape of the XXI U-Boat that was making such a big impression in 1945. I am not aware of any other experimental hull in the Royal Navy. The LYON shape that became the revolutionary USS ALBACORE was first proposed in 1948 and was not laid down until 1952 and it seems unlikely to have had any influence on the thinking of the Royal Navy in 1945. (Ref 12)
Hackmann (Ref 15), précis of pages 366 & 337
In 1946 the RAF became involved in the planning of A/S warfare when the Joint Air Warfare Committee was formed with two sub committees - Tactical and Technical. An important concept born at this time was the Hunter Killer submarine.
The Royal Navy began to explore the possibility of an A/S submarine, seen as an answer to the Russian submarine threat, in 1947. This concept was first tried out on a tactical table and subsequently in actual sea trials.
The A/S role emphasised the need for quieter submarines and so noise reduction research started during the war was now being tackled with increasing vigour.
Comprehensive noise trials were started in Britain in 1946 with TRADEWIND. The Loch Goil range was improved for this purpose and the ARL reviewed the whole problem of noise trial procedures and measurements in order to meet the new Staff Requirements for quieter submarines.
The first British submarine hydrophone array was not introduced until 1956. This set, Type 186, codenamed 'Knout' was an updated version of the wartime German GHG system.
To avoid misunderstanding, note this requirement is for the first two of eight fast submarines, not the five that were streamlined.
'T' CLASS SUBMARINE CONVERSION - DRAFT STAFF REQUIREMENTS
Enclosure - Flag Officer Submarines letter No 546/SM 472 dated 20th May 1948 to the Secretary of the Adimiralty.
Item 17 - The following equipment is required to enable the submarine to fulfil its primary (A/S) role, and to enable it to carry out co-ordinated attacks submerged:
Item 18 - Particular attention is required to be paid to placing the above equipment to give the best possible performance, and the latest material advances are required to be incorporated in it where possible.
Item 19 - The best available method of presenting the information derived from the above equipment is required.
Item 20 - The Asdic office must be large enough to accommodate the controls of all sets fitted and compete with the fluctuations of pressure occurring while snorting. It should be pressure tight so that interference with the listening efficiency is kept to a minimum.
Item 21 - Efficient communication is required between the Asdic office and the control room.
Item 22 - Silent operation is required at as high speeds as possible both while snorting and on motors.
Item 23 - Auxiliary machinery to be sound insulated in accordance with best existing standards.
Note: Hackmann (Ref 15) indicates that the FOSM requirements for a Four Square system Item 17(a) were not met by the time the first boat was commissioned in 1952. It would seem a type 167 set was fitted much later to these converted submarines. This increased need for ASDIC space had to be provided in a Control Room no bigger than the original un-modified boat, until the last four conversions had 3.5 feet added to the after end of the control room in addition to the 14 feet added to the Engine Room in all the conversions.
I actually served in the TRUNCHEON in 1951 in the motor room and can confirm that the starboard side of the fore ends had several cabinets of electronics and scientific staff were often taken on exercises. JT sonar is described at http://www.maritime.org/radio-jt.htmThe 5 foot rotating tee-shaped hydrophone was fitted more less where the US Navy Fleet Submarines had it installed on the fore casing. As far as I am aware this sonar was merely the standard fit on Fleet Submarines towards the end of the war, replacing or augmenting the older JP. However it operated in a different basic mode to the Royal Navy sets and this may have been the attraction in S/M vs S/M warfare experiments. (Ref 15) In the early fifties while serving on unmodified another boat, we were engaged in an elaborate two week Sm vs Sm exercise that involved about five submarines, submerged, circling the Shetland Isles taking water shots at each other. Each boat keeping detailed logs that were later collated into a complete picture. Unfortunately, according to our 1st Lt, the results that came out some months later, showed six boats in the exercise not five. It was apparently concluded a wily Soviet boat had joined the circle!
Captain B.W. Taylor DSC Royal Navy, C of S to FOSM - transcript of secret lecture to Senior officers Technical Course, 6 Feb 1951. Royal Naval Submarine Museum Archive A 1997/88. "SUBMARINE DETECTION - Development of Low Frequency Hydrophones and submarine version of Four Square ASDIC to be housed in a streamlined dome on the fore casing. American JT Sonar supplied to Royal Navy as an interim measure."
The dates for the conversions of the large US Navy Fleet Submarines (Ref 133) are listed to allow comparison against the Royal Navy programmes of the time. Interested readers will note that these boats achieved better submerged speeds for the same power than the smaller 'T' (conversion) class. The obvious explanation is that these big boats had lower hull resistance following conversion, though it may well be connected to their much lower shaft rpm at Maximum submerged speed. Not an option for the designers of the Royal Navy boats who gained the increased submerged speed by substantially increasing the rpm of the motors.
USS IREX first snorkel - no other mod's - completed 1947. A telescopic system. Maximum submerged speed 9 knots (The Royal Navy had a "fold-down" snort fitted to the HMS TRUANT 1946)
G1 - two experimental boats, four batteries, no hull extension needed as existing motors for surface diesel-electric drive already large enough for the Maximum submerged speed 18.2 knots (rated) knots given the additional batteries - fiscal year 1947.
GII - 24 operational four battery boats including the original two G1 - fiscal years 1948-1950, completed from 1949 to 1951. Maximum submerged speed 16 knots (rated).
G1A - 10 boats with the original Fleet Submarine two battery spaces but with improved cells, a more modest conversion brought about by budgetary restraints - fiscal year 1951, completed 1951. Maximum submerged speed 15 knots (rated).
G11A - 16 boats, same as G1A but one of the four diesel generators removed to create more space for sonar etc, completed 1952 - 1953. Maximum submerged speed 14/15 knots (rated).
Hunter-Killers SSK - 7 boats, a radical anti-submarine modification - fiscal year 1950/1952. Alden - Abandoned as a concept in 1959 when the fast SSN made them ineffective. Maximum submerged speed 9 knots (estimated). SSK reverted to SS with the all submarines assuming the responsibility for the anti-submarine mission.
Fleet Snorkel - 18 boats, a formal program to fit snorkel, though other boats were so fitted in refit. Fiscal year 1951-1954, completed 1951-1952. Maximum submerged speed 9 knots (rated).
GIII - 9 boats of GII, all received a hull insertion to create more operational space, all GII were intended to be so extended but budgetary restraints prevented any more. Fiscal year 1962 - completed 1962-1963. Maximum submerged speed 14 knots rated. Other Fleet Submarines were converted to radar pickets and other similar uses that are not listed here (Ref 8, 13).
It is worth briefly considering the "enemy" in 1950. The new Soviet boats would be the large, long range ZULU (611) capable of about 14.5 knots submerged with significant endurance and the smaller Whiskey (613) capable of 13 knots submerged. The former was not a great success until it reappeared as the Foxtrot (641) in 1958. The latter over time, became one of the most numerous classes ever built. They were reported as not being particularly "quiet" boats. Appearing in an improved form in the mid-fifties as the Romeo class (633), still maximum 13 knots submerged but not many built for the Red Navy, but adopted by the Chinese Navy in built in their yards in significant numbers. The point is that none of these boats were replicas of the feared but untried XXI U-Boat, but adequate vessels suited to the Soviet needs of the time (Ref 17).
Early post war submarine development took place at a time when the nation was tired of war and Governments planned many social reforms.Significant events in these years were the struggle to get its peacetime economy back under control with pressures from rebuilding and repaying war loans. A policy of selective nationalisation (the Bank of England, coal, electricity, gas, railways, road services and steel) and the introduction of a tax-funded National Health Service. Bread rationing ended in the UK 29 July 1948 and clothes rationing ended 15 March 1949. Butter and meat rationing continued until 1954. The British could only buy "seconds" for many household goods, the best going for export. Clothes and furnishings still carried the wartime "Utility" brand and the social and economic impact of the war was to be felt by the population for many years.
FOSM letters imply an atmosphere of financial restraint in regard to spending on submarines despite 10% of GDP being spent on defence, there were many competing defence projects, not the least nuclear weapons, together with the contentious development of very expensive delivery systems. The battleship Vanguard was commissioned. Carriers and support units were very active helping to conduct an air war in Korea whilst the army bolstered by conscripts were fighting on the ground in a bitter contest. This would have affected spending decisions made by the Admiralty at least until the cold war policies started to take effect. Streamlining would have been a cost effective measure that would have maintained a reasonable parity with other navies during these times.
It should not be overlooked that always in the background through the fifties was the expensive HTP experimental programme, that had it been successful would surely have seen a fleet of operational submarines based on this propulsion system that had so much promise . It is not unreasonable to presume it must have created a serious hiatus of sorts in submarine construction planning in the first part of the fifties . Then came the momentous commissioning of the first nuclear submarine USS Nautilus in 1955 that changed the submarine scene for ever.