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Chapter 29: Communications

1. This chapter is confined to the effect on submarine design of fitting W/T equipment as it developed. In the Holland boats the effect was negligible, by 1915 it had a marked effect and by 1925 had become an item of major importance in the design. Hydrophone gear was first fitted during the 1914-18 war. Asdics first appeared in the mid-1920's.

29.1 W/T Equipment

2. Lipscombe states that 'W/T was fitted for the first time in the D Class. Previous boats had fitted their own receiving sets but no receiving or transmitting sets had been incorporated in the design. The W/T aerial was rigged to a mast. Before diving the mast had to be lowered by hand and the W/T aerial stowed away carefully along the side of the vessel'. It is certainly true that W/T in the early vessels was very simple but anything more sophisticated could not really be expected.

3. Plate 1 of the Holland boats shows a large 'box for wireless telegraphy gear' just forward of the control room with a '2in connection for wireless telegraphy' overhead in the pressure hull close by. The mast for the W/T aerial was rigged aft of the conning tower and was portable as were other topside fittings such as the steering wheel, ventilators and the like. The aerials were undoubtedly taken inboard when diving. These arrangements would have been fitted during building in 1902.

4. Similar but undoubtedly improved arrangements continued in the following classes until in November 1912 it was approved for Type 10 W/T installation to be fitted in all E Class, all D Class and some C Class vessels. By this date all the D Class had been completed and E1 was launched the same month. The total weight of the installation was 2437 Ib.

5. A typical arrangement in the E boats is shown in Plate 14. A W/T cabinet about 3ft 6in. square is on the port side of the officers' quarters. The W/T deck tube is on the starboard side and is shown extending to the height of the guard rail stanchions. It would appear to be a fixture. The aerial arrangement varied with development. The portable mast at the after end of the bridge gave way to one of two or three sections which could be 'struck down' in sequence so that the top when housed was below the top of the periscope brackets. The aerial led from the top of the mast and was tailed to eyeplates or tripods forward and aft on the casing and later to short W/T masts which could be housed mechanically inside the casing. As would be expected various classes and individual boats in classes had various arrangements at various times.

6. During the war it was decided that overseas submarines should be fitted with special long distance wireless. As a result some of the E Class had one beam torpedo tube removed in order to fit a suitable W/T cabinet.

With this long range W/T two high masts, stated to have been of folding type, were sited about half the length of the boat apart and carried a flat roof aerial. Of the eighteen E Class boats remaining in the mid-1920's only three had had one torpedo tube removed presumably to fit the long range W/T whilst there were four minelayers which did not have the beam tubes and could have had this W/T. The remaining eleven boats all had their original torpedo armament which means that they had not been fitted with the long range W/T or had found a way of fitting improved W/T without having to remove one tube.

7. The early double-hull type submarines were fitted on the lines of the early E boats until the G Class which had two tall telescopic masts about 95ft apart and two to three feet off the middle line, the lower tubes passing through and to the bottom of the pressure hull. The aerial in the down position would clear the bridge superstructure. Telescopic masts came into favour at this time and the J Class and K Class and K26 were similar to the G Class. The W/T office increased in size to 9ft 9½in x 4ft 5⅜in x 6ft high in the J Class and 4ft x 10ft deck dimensions in the K Class.

8. The M Class and L Class had a single telescopic signal and W/T mast on the bridge. In the L Class the lower tube of the mast extended from the top of the pressure hull to the height of the tops of the periscope standards and was on the middle line just abaft the after periscope. When raised the top of the mast was about 40ft above the pressure hull. The top of the aerial intake tube was at the extreme after end of the bridge. The W/T cabinet of about 35ft2 deck area was on the starboard side of the control room.

9. The requirements for Oberon increased considerably from the L Class and L50L50 Class installations. Late in 1924 consideration was given to the requirements for the overseas type submarines to follow Oberon. An essential item was stated to be 'W/T range of 1000 miles; 1500 miles if possible'. To obtain 1500 miles DSD required two 100ft masts 200ft apart and about 200ft2 of floor space for the office. This would have meant an increase in length of the projected design (for Odin ) by 18-20ft and about 100 tons in displacement. It was considered undesirable to increase tonnage and hence cost. Furthermore it was expected that there would be a limitation in total submarine tonnage which did happen later by the London Treaty.

The final Staff Requirements for Odin included the statement 'a W/T range of maximum distance with 50ft masts - a Kite aerial being acceptable for longer distances'. As finally approved one 60ft mast was substituted for the two 50ft masts since it was considered that 'this arrangement would give better results whilst adhering to the principles decided upon by the Staff.

10. The discussions in 1924, although for Odin, appear to have rebounded on Oberon. During the period the latter was building a rather free hand was given to W/T development and fitting. Large yards and aerials were supported from a telemotor operated telescopic mast amidships, with at first fixed tripod masts later superseded by telemotor operated telescopic stump masts at the extreme forward and after ends of the boat to take the tails of the aerials. In addition kite aerials, loop aerials and S/F coils appeared all of which attracted a mass of wires, insulators, supports and stays and winches. This led DNC to protest in 1926 that 'in the aggregate there would be an appreciable increase in resistance submerged and that the presence of all these fittings must result in far greater commotion of the water when the vessel is being navigated submerged and render her more easily discernible by aircraft' and 'although the W/T equipment of Oberon as originally designed was more extensive than in previous submarines and considerably more space provided inside and outside the submarine for its stowage and operation, several additions had been made during building and in consequence the W/T space has proved too small'.

11. However little was done to improve matters. The result was a considerable reduction in submerged speed in both Oberon and the first of the Odin Class. In fairness it must be said that the growth in topside fittings was not confined to W/T gear. Following speed trials in Oswald in 1929 efforts were made to clean up the topsides and attention paid to streamlining fittings which included signal yards, stays and supports.

12. The following list of the type of W/T installation in various classes was prepared about 1935:

Class Type Range-miles
H 14 200-300
L 14 200-300
or 46 Y 600
L50 14 200-300
OBERON 39X 1000

13. The following points are relevant to classes from X1 onwards:

  • In X1 one W/T mast was at the foreside of the bridge, and one well aft of four tubes which telescoped inside the pressure hull. In Odin the telescopic mast was on the bridge and telescoped into a fixed tube the top of which was just above the level of the bridge side plating. The mast press was in the superstructure. This was an improvement on the L Class arrangement. In the stowed position the head of the mast came outside the protection of the jumping wire.
  • In the mid-1930's RA(S) expressed his concern about the number of telemotor leads running outside the pressure hull and the fact that they may leak especially under depth charge attack. At that time items concerned included the forward hydroplane housing gear, the capstan gear, the bow buoyancy and No 1 main tank vents, the main W/T mast, the W/T stump masts and the frame coil masts (Thames and Porpoise only). He requested that all such telemotor pipes outside the pressure hull should be abolished. This was done in new construction as far as possible.

29.2 Hydrophones

14. A report dated 9 February 1909 stated that 'submarine sound signalling had been fitted in certain submarines and tests carried out with bells fitted on the Shambles and Tongue Light Vessels'. Development went on and although progress was disappointing to some, Fessenden and Jet Signalling Gear was fitted in the E boats during the war.

In 1916, at the time the later vessels of the E Class were completing, the L Class specification included Fessenden gear and hydrophone gear. The Fessenden gear was fitted port and starboard sides at mid height in the forward end of the saddle tanks. The R Class ordered in October 1917 had a 'much more sophisticated arrangement of five powerful and sensitive hydrophones by which they could approach an enemy and obtain her position without using the periscope'. Thereafter hydrophones with a separate Type 116 office, as it was then called, became standard in submarines.

29.3 Asdics

15. Asdics were introduced in the 1920's under a cloak of secrecy. In the Odin Class although asdic offices were built in by the shipbuilders they were not fitted out until after delivery of the vessels and then at a Dockyard. This also applied to the domes although the seats were fitted and machined by the shipbuilder.

Oberon and later vessels were fitted but few of the older boats received asdics. In 1938 of nine H boats remaining only H32 had asdics.

29.4 Jumping Wires

16. Although perhaps not relevant to this chapter, except as a limiting factor on the fitting of W/T arrangements, is the introduction of jumping wires in submarines. In April 1908, C14 was fitted with a 'wire obstruction and bumkin'. A lengthening piece of teak was put on the ventilator on the conning tower and a 2½in diameter steel rod on top of it. The total height of the teak and rod was 11ft 9in. This carried a l½in FSW rope to a slip forward and a shackle aft. This appears to have been the beginning of the obstructional wire later called the jumping wire.

The jumping wire thereafter became a standard fitting and all topside equipment in the diving condition ex periscopes had to stow within the safety of the jumping wire. The jumping wire was abolished during the Second World War.

Chapter 28: Gun ArmamentChapter 30: Anchor and Cable Arrangements