The following article was published in two parts, the first half in the November 2001 (Vol. 42 / #4) issue of the Old Timer's Bulletin, the official journal of the Antique Wireless Association. The concluding portion followed in February, 2002 (Vol. 43 / #1).
Copyright © 2002, The Antique Wireless Association, Inc.
The Marconi Wireless Installation in R.M.S. Titanic
by Parks Stephenson
Changes/updates made since this article was originally published are highlighted in green font.
In the early morning hours of 15 April 1912, a high-pitched musical tone sang out for hundreds of miles across the North Atlantic in a desperate plea for help. The White Star liner R.M.S. Titanic had struck an iceberg, and her 5-kW Marconi installation was signalling her death knell.
Over the years, Titanics Marconi wireless set and her steadfast operators have attracted a good deal of public attention. Titanic as well as wireless historians have offered technical descriptions of the equipment and its capabilities in various publications throughout the years. Unfortunately, much of the previous research drew too heavily on contemporary press releases that encapsulated the details of the standard 1.5-kW marine set installed at that time in most ships serviced by the Marconis Wireless Telegraph Company, Ltd. (hereafter referred to as the Marconi Company). The 1.5-kW set was, in fact, originally intended for the two sister ships, Olympic and Titanic, before their completion. As it turned out, though, the technology advanced so quickly that Olympic would be the first merchant vessel serviced by the Marconi Co. to receive a 5-kW plain spark installation, just prior to her maiden voyage in June, 1911. Titanic would receive the additional benefit of a synchronous rotary spark discharger the following year. This change in installation would largely escape public notice.
Titanics wireless set had a nominal working range of 250 nautical miles, but signalling more distant stations was possible. At night, ranges of up to 2,000 miles were attained with sets of similar architecture. The use of the "T" type aerial afforded greater power and sensitivity both fore and aft, so optimised performance could be expected when the ship was pointed either toward or away from a distant station.
The location of the wireless suite aboard the Olympic-class ships causes some confusion to historians because of constant evolution in design. The original configuration for the class, as used initially on the lead ship Olympic, put the wireless equipment on Boat Deck inside the Officers Quarters complex against the port side of the deckhouse. Most plans and photographs issued to the press reflect this early configuration. Between the time that Olympic and Titanic were fitted out, however, the owners decided to relocate the wireless suite of the latter ship inboard on the centreline of the same deck (taking the space occupied on Olympic by the Officers Smoke Room and Pantry) in order to free valuable windows for use by First Class staterooms. Whereas Olympics Marconi Room had a window on the port bulkhead directly above the operators desk, Titanics would instead have a 6-pane skylight overhead. Later in Olympics career, the same need to maximise window space for passenger accommodations would dictate a similar move of her wireless suite to centreline.
On board Titanic, the wireless equipment was housed in a series of interconnecting rooms the sound-proof "Silent Room," in which noisy transmitting equipment was located; the Marconi Room, an office in which contained the operators work stations, manipulation keys, and receiving equipment; and the Bed Room, which contained the operators berthing.
The wireless set was operated and cared for by Marconi Company employees, who were by routine assigned to Titanic for the duration of one voyage and, therefore, not considered part of the normal crew. The uniforms worn by the two Marconi operators aboard Titanic were made distinguishable by Marconi emblems on the buttons, sleeves, and cap. Marconi employees were not directly responsible to any of the ships crew, having only certain responsibilities to the ships Master. Most of their time was spent within the Marconi suite, with the exception of meals, which were taken in the dining saloon reserved jointly for Marconi and Postal employees on C Deck.
Details of the Wireless Installation
The Marconi wireless equipment set consisted of both transmitting and receiving apparatus. The transmitting apparatus consisted of five distinct circuits that converted direct current from the ships electrical mains into regulated, high-power, radio-frequent oscillations that were then transmitted into the atmosphere by way of the ships aerial. Much of this equipment was located in the Silent Room. The receiving apparatus, located on or adjacent to the aft-facing operators desk in the Marconi Room, was connected into a single circuit that converted radio-frequent oscillations collected by the aerial into audible signals that could be heard by the operator. An auxiliary transmitting set, also located in the Marconi Room and capable of producing a plain spark in the event of a casualty to the main transmitting set, was also provided.
The Direct Current transmitting circuit carried the 100-volt direct current (D.C.) from the ships lighting circuit via a local electrical distribution box to the main switch for the Marconi equipment. A motor-generator, rated for a 5-kW output and consisting of a D.C. motor directly coupled to an alternator on a common bedplate, converted the supplied D.C. into alternating current (A.C.). Two field regulators one in series with the motor, the other in series with the alternator controlled the speed of the motor and the field of the alternator, thereby allowing the operator to adjust the spark. Four graphite sticks absorbed any oscillations or spikes in potential, thereby protecting the windings of the motor and alternator.
The Low Frequency primary circuit carried the low-potential A.C. generated by the alternator to the primary winding of the transformer. A double panel switchboard allowed for control and monitoring of current flow through both the motor windings (D.C.) and armature (A.C.) as well as supplying fuse protection for the primary circuit. A shaded pilot lamp on each switchboard illuminated whenever power was being supplied to the respective board. An adjustable spiral inductance was used in conjunction with the speed of the motor to provide resonance in the circuit by bringing both current and voltage into phase. A manipulating key on the operators desk activated a double electromagnetic key in the primary circuit, which was in series with the closed-core, step-up transformer. By closing the key, the operator caused the alternator to connect to the transformer, which raised the voltage of the A.C. to a level, normally 10,000 volts, required to charge the main condenser.
The High Tension circuit carried the high voltage current stepped up by the transformer secondary to the condenser. Two air-core "choking" coils protected the windings of the transformer secondary from any high-frequency oscillating discharge currents from flowing back from the condenser. The four cells of the main condenser were of the "double plate, whole plate" type and controlled in configuration by a Swiss commutator mounted above the condenser tanks. The condenser stored the high-voltage charge until it built up to the point where it reached the break-down voltage of the spark gap. Upon discharge, the condenser charged again. This cycle would repeat itself numerous times as long as the key was down, completing the circuit. To create the normal 600-metre (500-kHz) "long" wave, the cells were configured in parallel. For the 300-metre (1000-kHz) "short" wave, both the main condenser banks and transformer were configured in series to provide the extra energy required to transmit the wave. In addition, an extra condenser had to be inserted into the oscillating circuit so that the total capacity of the aerial could be reduced to a value suitable for the shorter wave.
The High Frequency Primary or Closed Oscillating circuit set up an oscillating current of high potential for transmission. A spark gap in the circuit performed the following functions: 1) It kept the circuit idle until the condenser fully charged; 2) it then allowed the high-potential current to discharge in the form of a spark, thereby creating a radio-frequent oscillation; and 3) it "quenched the spark" by returning the gap in the circuit to its non-conductive state. The spark gap used in Titanic was of the synchronous rotary type, which was essentially a metal disc studded with discharge electrodes that was keyed and mounted on the shaft of the alternator. The disc spun past two stationary electrodes that were connected in series with the closed oscillation circuit. Receiving operators could easily distinguish the high-pitched musical note emitted from a synchronous rotary discharger from the "Shhhh" sound emitted by a plain spark discharger. A spiral inductance was included in the circuit to tune the oscillation frequency to the wavelength of the aerial circuit and a coupling transformer, commonly known as a "jigger," roughly coupled the closed oscillation and wave-radiating circuits together.
The Radiating, or Open, Oscillating circuit inductively transferred the high-voltage oscillating current from the closed circuit to one open to the aerial. The 325-metre fundamental wavelength of the aerial required an additional inductance to provide the additional functional electrical length needed to transmit the long wave. A small lamp in series with an adjustable inductance coil, shunted between the jigger and the ships ground, provided a means for fine-tuning the circuit. Two protective brass terminals one for the long-wave configuration, both together for the short wave which connected the oscillation and aerial circuits to earth by way of an air gap protected the receiving apparatus from the high potential of the transmitting apparatus and also provided protection for the aerial against lightning. Marconis use of these earth arresters alleviated the requirement for a separate changeover switch commonly found in the sets manufactured by other wireless companies.
The Receiving circuit detected electromagnetic energy exciting the aerial and converted it into audible signals for the operator to hear. A magnetic detector, commonly known as "Maggie," working in conjunction with a Marconi multiple tuner, replaced the less-efficient coherers of previous years. The detector was used to convert the received radio-frequent oscillations to electrical currents while the three distinct circuits of the tuner largely filtered out unwanted frequencies and atmospherics (known as "X"s). The signals passed through a telephone condenser, which filtered out unwanted harmonics. The filtered electrical impulses acted on diaphragms in the head telephones, causing them to vibrate and thereby creating sounds that the operator could hear. A Marconi valve receiver was also provided as a back-up to the detector/tuner combination. A separate battery and charging switchboard were provided to supply the 6-volt power necessary to heat the filaments of the back-up receivers Fleming valves. A two-way switch toggled the detector/tuner or the valve receiver into the receiving circuit.
Titanic was fitted with a Marconi twin "T" type aerial, rising vertically from the roof of the Marconi Silent Room, connecting with four horizontal wires strung between the ships two masts. Positive electrical connection was made between each vertical lead-in and its corresponding wire in the horizontal flat top by means of a McIntyre connector. Two 20-foot spreaders at either end of the flat top portion spaced the two inner wires 8 feet apart and the two outer wires 6 feet from the inner wires. The aerial spreaders were supported by bridles of tarred hemp rope (ratline), which in turn could be raised or lowered by rope halyards run through reef blocks attached to the top of their respective masts. The forward spreader had four eyebolts, each of which took an aerial strain insulator, from which an individual aerial wire was run.
The fundamental wave length of the aerial was 325 metres, which provided a good value of aerial current at the 600-metre adjustment and a fair value at the 300-metre wave adjustment. Two reasons dictated the aerials physical length: 1) The aerial could not be reduced to less than one-half its physical length; and 2) Titanics two masts were stepped approximately 600 feet apart. The length of the horizontal wires was therefore limited to keep the 300-metre radiated wave within limits. This meant that the strain insulators for the after portion of the aerial were suspended over the space between the 3rd and 4th funnels, instead of attached directly to the aft spreader with the remaining wire aft of the insulators serving only as support. Also note that the lead-ins had to be taken from the exact centre of the flat top; otherwise, each branch of the "T" would have a different wavelength, making accurate tuning impossible.
A Bradfield type Deck Insulator, rated for the 5-kW marine generator set and able to withstand a minimum of 30,000 volts, was used to insulate the aerial from the steel structure of the ship. The insulator was elevated on an approximately 6-foot-high wooden trunk, square in cross-section, to keep it clear of a canvas awning that was part of the design for the roof of the Officers Quarters but never utilised during the ships short career. In order to protect the Bradfield insulator from the strain of the aerial being pulled by the wind, the lead-ins were firmly attached to a screw eye in the roof of the Officers Quarters and electrically isolated by a single strop insulator. Electromagnetic energy was transferred between the aerial and the Bradfield insulator by way of two flexible wires that ran from the terminus of the lead-in wires to the insulators shackle head. The brass terminal socket on the lower end of the insulator rod inside the Silent Room secured the wire connection to the Aerial Tuning Inductance as well as to the two plug sockets mounted on the aft bulkhead of the Marconi Room. The plug sockets were located within easy reach of the operator so that he could switch the aerial from the earth arrester to the induction coil in the emergency set.
In the event of a loss of power to, or a breakdown of, the main transmitting set, a Plain Aerial Coil Set, capable of producing a plain spark and operating continuously for at least 6 hours, was provided. Eight chloride accumulators were kept in a charged condition by power taken from the ships mains. A charging switchboard provided status lamps for the charging process and provided the switches needed to reconfigure the system so as to discharge the accumulators to power the emergency set. A 10-inch induction coil induced an alternating current strong enough to jump a plain spark gap, creating a signal that could be heard at least 80 nautical miles distant. A separate manipulating key was connected to the emergency set to control the discharging of the coil.
Other equipment completed the wireless installation. Pneumatic conveyor tubes transferred Marconigram forms between the Marconi Room on the Boat Deck and the Pursers Enquiry Office on C Deck. Passengers composed and paid for outgoing messages in the Enquiry Office; likewise, incoming telegrams were delivered down to C Deck for pick-up. A shunted buzzer, galvanometer, and portable wavemeter were included along with a special tool kit to test and adjust the circuits.
Unfortunately, not much remains of Titanics wireless installation today. The aerial was swept away when Titanics two masts were dislodged during the sinking. Photographs taken of the wreck soon after its discovery in 1985 show only the bent insulator connecting rod protruding from the gland mounted on the deck, surrounded by the square outline left by the caulking once used to seal the base of the now-absent aerial trunk. More recent video footage shows that the remains of the previously observed metal rod are now missing, either corroded away or knocked off by a visiting submersible. Footage of the interior of the Marconi Room to date has revealed only the electrical distribution box that was mounted on the forward wall, still hanging by the heavy wires that carried power from the ships lighting circuit to the Marconi switchboard. No other equipment has been found although James Cameron will be attempting to explore the interior of the Marconi and Silent Rooms in the course of filming his documentary, "Ghosts of the Abyss," in September, 2001. As far as can be determined at this time, however, there is not much remaining of the apparatus that alerted the world to Titanics plight and, in so doing, saved the lives of over 700 people.
Bradfield, W.W. "Wireless Telegraphy for Marine Inter-Communication." In The
Electrician Marine Issue 135, June 10, 1910
Bucher, Elmer E. Practical Wireless Telegraphy: A Complete Text Book for Students of Radio Communication, 3rd Edition. New York: Wireless Press, Inc., 1918
Harris, Percy W. The Maintenance of Wireless Telegraph Apparatus. London: The Wireless Press Ltd., 1917
Hawkhead, J.C. and Dowsett, H.M. Handbook of Technical Instruction For Wireless Telegraphists, 2nd Edition. London: The Wireless Press Limited, 1915
Larkman, Alfred E. Browns Marine Electrician for Sea-Going Engineers, 2nd Edition. Glasgow: James Brown & Son, 1914
Sewall, Charles H. Wireless Telegraphy: Its Origins, Development, Inventions and Apparatus. New York: D. Van Nostrand Company, 1903
Stanley, Rupert. Text Book on Wireless Telegraphy. London: Longmans, Green & Co., 1914
"The Equipment of SS. Olympic." In The Marconigragh, July 1911
"Wireless Equipment of the Titanic." In The Marconigraph, May 1912
Report on the Loss of the S.S. "Titanic." London: His Majestys Stationery Office, 1912
The Shipbuilder, Vol. VI, Special Midsummer Number. Newcastle-on-Tyne: Marine Publications, Ltd., 1911
The Year-Book of Wireless Telegraphy & Telephony 1914. New York: Marconi Publishing Corporation, 1914
The author wishes to acknowledge the contributions of the following people: Ken Marschall, who provided invaluable assistance in supplying and deciphering photographs showing the aerial connections of both Olympic and Titanic; Bill Sauder, who reviewed the draft and provided much-needed technical advice; Eric Sauder, who reviewed the draft for the proper historical perspective; Tom Perera, editor of the "AWA Review," who encouraged me to post an excerpt from this article on his website and is helping to bring my wireless research to publication; and Jim Kreuzer of New Wireless Pioneers, who has helped me with key resource material on Marconi marine sets over the past year or so. Additional thanks are owed to Neal McEwen, webmaster for "The Telegraph Office" website, who provided technical comment on the report after publication. Without their help, I could never have come close to understanding Titanic's true Marconi configuration. Some portions of the text have been changed to reflect the discoveries made by James Cameron during his 2001 expedition to the wreck.
A more comprehensive component-level description of the Marconi installation aboard Titanic was published in the AWA Review, Vol. 15, in August 2002 by the Antique Wireless Association of Breesport, NY.
For the results of James Camerons 2001 exploration of the Marconi spaces, read the authors
"Quicklook analysis of Titanic's Silent Room exploration"