See also these files which are necessary to understand the text below:-

1912 two. pdf
1913 3  .pdf - Parts of this file show you the very first submarine aerial rig and other interesting aspects of the the FIRST FIT.

I first wrote this page and these file for the RN Radar and Communications Museum website of which I am the webmaster and author of all material thereon, which can be found at - please note that the material is COPYRIGHT.

 Submarine Installation - the first submarine so fitted was the B5 - This was called the Type 'X' Fit. The 'B' Class consisted of 11 boats all of them obsolete by the start of WW1. The characteristics were as shown below and here is a picture of the B4 [but without a main roof aerial] her sister boat, with apologies for not having a picture of B5The W/T fit was the same as the Type 4 Destroyer kit but with some basic alterations to the circuitry.  At all times in a submarine there is a very real danger of a battery explosion.  Like all batteries, they "gas" and give off hydrogen.  Sparks and hydrogen are not good bed-fellows unless fireworks are the order of the day. Hence, many of the modifications were addressing the problems of sparking and brushing.  Airtight boxes have been used for The two-knob Morse key [completely boxed in unlike the surface version] and have had their respective key-bars extended and each protrudes through an airlock also to avoid sparking.  Platinum contacts have been used in lieu of silver. Submarines were given a Tune of 600 feet = 1.64MHz to transmit on and a suitable receiver with additional tuning so as to receive her own waves plus that of destroyers and Harbour Defence sets. Just like a surface ship, the boat had a W/T office and within, a silent cabinet wherein the operator sat - it was very tiny!  The aerial was enormous and consisted of a four-fold roof type, which could be lowered from the conning tower. The strength of a submarines pressure hull not only depends upon the material used [shape, metal, welding etc] but on the fewest possible holes being made in it.  When W/T was introduced into boats, a 'deck tube' [to connect the communications equipment to the aerial] having a diameter of 4 inches was cut through the pressure hull.


If you want to jump ahead to see the submarine aerial [although you will read about it all when you get to 1913] have a quick look at page 7 of 12 in file 1913.three.pdf.

HMS Forth, the submarine surface depot ship, has a Mk1* set modified to operate of 'D' Tune so that she can communicate with her boats. Look how they have spelt Forth - in one place as Fourth. A report by the Commanding Officer of HMS Forth.  1 PO Telegraphist and 1 Telegraphists sent to sea in B5 to communicate with Forth - good results.

Diagram showing new Motor Buzzer Set.
Diagram of the Submarine Set. Let me stop awhile to briefly explain the circuit - I am an ex-submariner so have a vested interest !
Before we look at the submarine set specifically, let us consider this drawing to the left.  This is how a basic spark transmitter works.  When the Morse key is pressed {**} AC current flows through the Morse key into the primary circuit of the transformer.  This produces a very high voltage across the secondary of the transformer.  D and E respectively form the primary and secondary of the oscillator transformer. The circuit C, F G and D form the sparking circuit and also the oscillator circuit of a wavelength dictated by the value D.  AC alternating + and - charges and then discharges the transmitting condenser.  When it discharges, it does so across the spark gap. A  high voltage high frequency oscillating current is transferred onto E which increases the voltage to a very high level and then onto the aerial.

Now lets look at the very first submarine installation.
The transmit side can now be completed by using the letter indicators in the picture above and applying them direct onto the submarine set. When the Morse key is pressed, contact 1 is raised to touch contact 2 thereby joining the braiding and the centre core of the aerial cable together shorting out the aerial to the receiver. Contact 4 is directly connected to the primary B so that pressing the key touches contact 3 and current flows through the primary stage at 48V AC inducing a current into C the secondary - then see above for the rest of the story. Contact 6 is permanently connected to the + terminal of a low voltage DC circuit and on pressing the key the circuit is completed through contact 5: you will see two lamps in series on the line between the + voltage and the key position 6 and these burn accordingly to inform the operator that it is "safe to transmit". Note the bits and pieces used to cobble this fit together - "Oscillator T.B.D. Pattern" = Torpedo Boat Destroyer/also TBD Condenser. "HD Transformer" = Harbour Defence Set; "HD I.C." = Harbour Defence Set Impedance Coil; on the receiver "PHD Sliding Condenser" = Portable and Harbour Defence Set etc. The Type 'C' receiver has two detector options and tuning arrangements to allow the boat to listening to the destroyer wave and the Harbour Defence wave. Note the LS of the oscillator primary = D in the diagram.  It is 8.46.  Remember λ [in feet] = 206 x square root of the LS.  The submarine operates on a Tune  of 600 feet, so 206 x 2.9086 should equal 600.  It does, almost!


Many problems existed, the majority to do with the submarine operating environment. Distances achieved very short, 1 to 2 miles and at the very best 25 miles [although Defiance thinks 50 miles possible] where strength 12 [yes, twelve] was heard. The aerial has no stays and the masts wobble about all over the place. It is considered essential that a Telegraphist is necessary because it is too much to ask a boats officer to come off the bridge or from the engine room to sit in the silent cabinet and operate W/T equipment etc etc., especially when he has his own duties to perform as well. HMS Defiance' comments agree that a Telegraphist should be a member of a submarines ships company.

Submarine Fits.  Submarine Set Type X= Portable Form, and more or less a modified Type 4 Destroyer Set was fitted to HM Submarine B5     was not suitable for all boats.  The system was subsequently much modified {and became the Type 10 proper} to be fitted into Classes B, C, D, E and X. The submarine motor alternator gives 1kW @ 100 c/s 70V RMS.  Two versions. One working from 95 to 140 V DC for classes B, D, E and X, and the other from 155 to 200V DC for class C.  Can be used at all times when on the surface whether charging main battery or not.  The power oscillator tuned circuit will give a maximum of LS21 = 944' = 1.04MHz., [remember the maximum means the longest wave - we would talk about its lowest frequency].   Normal Tunes permit the use of Harbour Defence Wave [New Tune C] = 514' = 1.9MHz; Submarine Wave [the forerunner of 4340kHz]  [New Tune D] = 635' = 1.55Mhz; Destroyer Wave [New Tune E] = 756' = 1.3MHz.
The W/T Office with its traditional Silent Cabinet was quite an affair.  Look at Fig 9 for example.  Here, the material used is [a] substantial wooden support frame [b] lead [c] canvas [d] felt [e] 5-ply [plywood] [f] sound proofing wood.

For the very earliest submarine W/T aerial see the picture in the file.  The aerial was functional but as one would expect in those early days cumbersome and inefficient.  In the bigger boats, the D and E Classes [this is D1 with a small Holland Boat approaching her portside ballast tanks] the overall aerial height was 35 feet but in a small boats, the B, C and X Classes the aerial was 30 feet [this is the Boat B10 below].  Notice on the "Typical Rig" Drawing that the Deck Tube is quite someway aft of the conning tower  so this marks out the position of the W/T Office. Also, you will note doted lines on three parts of the casing two forward and one aft.  These are the stowage position for each of the three support masts which are drawn upright and operational. It must have been some task lowering these masts at the order 'open up for diving' and fortunately in those days, aeroplanes were not what they were come WW2. However, the text tells us that in many circumstances the Skipper would dive with the aerial still fully rigged and taut and that there were no set procedures or Standing Orders. The turbulence caused by such a large mass of wire aloft would have created some all telling noises plus the very obvious danger of anything snapping and ending up wrapping itself around the screws or hydroplanes.


For the two diagrams forming the Type 10 Connections, there is a generous overlap provided in case you want to print both pages and then marry them together for a better view of the system.
The idea of HMS Vernon providing telescopic masts was wonderful although two independent masts being raised or lowered with one piece of wire stretched between them might have caused problems with under or over stressed tautness.
Before WW1 started, no fewer than 26 British submarines were fitted with W/T with a further two Commonwealth boats of the 'E' Class.
In the 1914-1915 financial year there was an ambitious fitting programme planned,  and for the future [probably marred by WW 1 although our submarines were not overly  involved in the war in any great numbers] where HMS Vernon's intentions were to redesign and fit a W/T Office more in keeping with the hostile environment of submarines operations.