Structure of the RMS Titanic - 1912

Titanic Outboard Profile, Boat Deck and Orlop Deck Plans

Titanic Outboard Profile, Boat Deck and Orlop Deck Plans. International Marine Engineering (May 1912) p. 199. GGA Image ID # 1050d41670

From: Congressional Serial Set 1912 – Loss of the steamship “Titanic” 
Loss of the steamship Titanic - Presented by Mr. Smith of Michigan  - AUGUST 20, 1912 -  p. 571

Topics covered in this article include a discussion of the structure, water-tight subdivision, water-tight doors, side doors, accommodation ladder, masts and rigging, life-saving appliances, pumping arrangements, electrical installation, electric heating and power and mechanical ventilation, wireless telegraphy, and more.


The vessel was built throughout of steel and had a cellular double bottom of the usual type, with a floor at every frame, its depth at the center line being 63 inches, except in way of the reciprocating machinery, where it was 78 inches.

For about half of the length of the vessel this double bottom extended up the ship's side to a height of 7 feet above the keel.

Forward and aft of the machinery space the protection of the inner bottom extended to a less height above the keel. It was so divided that there were four separate water-tight compartments in the breadth of the vessel.

Before and abaft the machinery space there was a water-tight division at the center line only, except in the foremost and aftermost tanks. Above the double bottom the vessel was constructed of the usual transverse frame system, reinforced by web frames, which extended to the highest decks.

At the forward end the framing and plating was strengthened with a view to preventing panting and damage when meeting thin harbor ice.

Beams were fitted on every frame at all decks from the boat deck downward. An external bilge keel about 300 feet long and 25 inches deep was fitted along the bilge amidships.

The heavy ship's plating was carried right up to the boat deck, and between the C and B decks was doubled. The stringer or edge plate of the B deck was also doubled. This double plating was hydraulic riveted.

All decks were steel plated throughout.

Fig. 44: Sections Through Boiler Rooms Nos. 1 and 2.

Fig. 44: Sections Through Boiler Rooms Nos. 1 and 2. The Shipbuilder (Midsummer 1911) p. 45. GGA Image ID # 10bcc0b520

The transverse strength of the snip was in part dependent on the 15 transverse water-tight bulkheads, which were specially stiffened and strengthened to enable them to stand the necessary pressure in the event of accident, and they were connected by double angles to decks, inner bottom, and shell plating.

The two decks above the B deck were of comparatively light scantling, but strong enough to insure their proving satisfactory in these positions in rough weather.

Water-Tight Subdivision

Electrically Operated Bulkhead of the General Type Installed on the Titanic.

Electrically Operated Bulkhead of the General Type Installed on the Titanic. Scientific American (27 April 1912) p. 380c. GGA Image ID # 10a419ff45

In the preparation of the design of this vessel it was arranged that the bulkheads and divisions should be so placed that the ship would remain afloat in the event of any two adjoining compartments being flooded and that they should be so built and strengthened that the ship would remain afloat under this condition.

The minimum freeboard that the vessel would have in the event of any two compartments being flooded was between 2 feet 6 inches and 3 feet from the deck adjoining the top of the water-tight bulkheads.

With this object in view, 15 water-tight bulkheads were arranged in the vessel. The lower part of C bulkhead was doubled and was in the form of a cofferdam.

So far as possible the bulkheads were carried up in one plane to their upper sides, but in cases where they had for any reason to be stepped forward or aft, the deck, in way of the step, was made into a water-tight flat, thus completing the water-tightness of the compartment.

In addition to this, G deck in the after peak was made a water-tight flat. The orlop deck between bulkheads which formed the top of the tunnel was also water-tight.

The orlop deck in the forepeak tank was also a water-tight flat. The electric-machinery  compartment was further protected by a structure some distance in from the ship's side, forming six separate water-tight compartments, which were used for the storage of fresh water.

Where openings were required for the working of the ship in these water-tight bulkheads they were closed by water-tight sliding doors which could be worked from a position above the top of the water-tight bulkhead, and those doors immediately above the inner bottom were of a special automatic closing pattern, as described below. By this subdivision there were in all 73 compartments, 29 of these being above the inner  bottom.

Plate 1: Cofferdam Bulkhead Salvage Pumps for a Large Ship.

Plate 1: Cofferdam Bulkhead Salvage Pumps for a Large Ship. Arranged for Electric Motor or Vertical Steam Turbine Drive. Longitudinal Secion on Left; Transverse Section shown on Right. How to Save a Big Ship from Sinking (1915) p. 24. GGA Image ID # 10e998eb91

Water-Tight Doors

Fig. 21: Double Cylinder Watertight Door.

Fig. 21: Double Cylinder Watertight Door. The Shipbuilder (Midsummer 1911) p. 26. GGA Image ID # 10b623f05f

The doors (12 in number) immediately above the inner bottom were in the engine and boiler room spaces. They were of Messrs. Harland & Wolff's latest type, working vertically.

The doorplate was of cast iron of heavy section, strongly ribbed. It closed by gravity and was held in the open position by a clutch which could be released by means of a powerful electromagnet controlled from the captain's bridge.

In the event of accident, or at any time when it might be considered desirable, the captain or officer on duty could, by simply moving an electric switch, immediately close all these doors.

The time required for the doors to close was between 25 and 30 seconds. Each door could also be closed from below by operating a hand lever fitted alongside the door.

As a further precaution floats were provided beneath the floor level, which, in the event of water accidentally entering any of the compartments, automatically lifted and thus released the clutches, thereby permitting the doors in that particular compartment to close if they had not already been dropped by any other means.

These doors were fitted with cataracts, which controlled the speed of closing. Due notice of closing from the bridge was given by a warning bell.

A ladder or escape was provided in each boiler room, engine room, and similar water-tight compartment, in order that the closing of the doors at any time should not imprison the men working therein.

The water-tight doors on E deck were of horizontal pattern, with wrought-steel  doorplates. Those on F deck and the one aft on the Orlop deck were of similar type, but had cast-iron doorplates of heavy section, strongly ribbed.

Each of the between-deck doors, and each of the vertical doors on the tank top level could be operated by the ordinary hand gear from the deck above the top of the watertight bulkhead, and from a position on the next deck above, almost directly above the door.

To facilitate the quick closing of the doors, plates were affixed in suitable positions on the sides of the alleyways, indicating the positions of the deck plates, and a box spanner was provided for each door, hanging in suitable clips alongside the deck plate.

Ship's Side Doors

Large side doors were provided through the side plating, giving access to passengers' or crew's accommodation as follows:

  • On the saloon (D) deck on the starboard side in the forward third-class open space, one baggage door.
  • In way of the forward first-class entrance, two doors close together on each side.
  • On the upper (E) deck, one door each side at the forward end of the working passage.
  • On the port side abreast the engine room, one door leading into the working passage. One door each side on the port and starboard sides aft into the forward second-class entrance.
  • All the doors on the upper deck were secured by lever handles and were made water-tight by means of rubber strips. Those on the saloon deck were closed by lever handles but had no rubber.

Accommodation Ladder

One teak accommodation ladder was provided and could be worked on either side of the ship in the gangway door opposite the second-class entrance on the upper deck (E).

It had a folding platform and portable stanchions, hand rope, etc. The ladder extended to within 3 feet 6 inches of the vessel's light draft and was stowed overhead in the entrance abreast the forward second-class main staircase. Its lower end was arranged so as to be raised and lowered from a davit immediately above.

Masts and Rigging

The vessel was rigged with two masts and fore and aft sails. The two pole masts were constructed of steel and stiffened with angle irons. The poles at the top of the mast were made of teak.

A lookout cage, constructed of steel, was fitted on the foremast at a height of about 95 feet above the water line. Access to the cage was obtained by an iron vertical ladder inside of the foremast, with an opening at C deck and one at the lookout cage. An iron ladder was fitted on the foremast from the hounds to the masthead light.

Plate 2: Bulkhead Salvage Pumps for a Large Liner or War Ship.

Plate 2: Bulkhead Salvage Pumps for a Large Liner or War Ship. Arrangement of Expulsor Pumps. Longitudinal Secion on Left; Transverse Section shown on Right. How to Save a Big Ship from Sinking (1915) p. 25. GGA Image ID # 10e9d45a81

Life-Saving Appliances

Life buoys —Forty-eight, with beckets, were supplied, of pattern approved by the board of trade. They were placed about the ship.

Life belts —Three thousand five hundred and sixty life belts, of the latest improved overhead pattern, approved by the board of trade, were supplied and placed on board the vessel and there inspected by the board of trade. These were distributed throughout all the sleeping accommodation.

Some of the Titanic’s Lifeboats on the Deck of the Carpathia

Some of the Titanic’s Lifeboats on the Deck of the Carpathia. Harper's Weekly (27 April 1912) p. 36a. GGA Image ID # 109dd0500d

Lifeboats —Twenty boats in all were fitted on the vessel, and were of the following dimensions and capacities:

  • Fourteen wood lifeboats, each 30 feet long by 9 feet 1 inch broad by 4 feet deep, with a cubic capacity of 655.2 cubic feet, constructed to carry 65 persons each.
  • Emergency boats:
  • One wood cutter, 25 feet 2 inches long by 7 feet 2 inches broad by 3 feet deep, with a cubic capacity of 326.6 cubic feet, constructed to carry 40 persons.
  • One wood cutter, 25 feet, 2 inches long by 7 feet 1 inch broad by 3 feet deep, with a cubic capacity of 322.1 cubic feet, constructed to carry 40 persons.
  • Four Engelhardt collapsible boats, 27 feet 5 inches long by 8 feet broad by 3 feet deep, with a cubic capacity of 376.6 cubic feet, constructed to carry 47 persons each.

Or a total of 11,327.9 cubic feet for 1,178 persons.

The lifeboats and cutters were constructed as follows: the keels were of elm. The stems and stern posts were of oak. They were all clinker built of yellow pine, double fastened with copper nails, clinched over rooves.

The timbers were of elm, spaced about 9 inches apart, and the seats pitch pine, secured with galvanized-iron double knees. The buoyancy tanks in the lifeboats were of 18 ounce copper, and of capacity to meet the board of trade requirements.

The lifeboats were fitted with Murray's disengaging gear, with arrangements for simultaneously freeing both ends if required. The gear was fastened at a suitable distance from the forward and after ends of the boats, to suit the davits. Life fines were fitted round the gunwales of the lifeboats. The davit blocks were treble for the lifeboats and double for the cutters.

They were of elm, with lignum vitae roller sheaves, and were bound inside with iron, and had swivel eyes. There were manila rope falls of sufficient length for lowering the boats to the vessel's light draft, and when the boats were lowered, to be able to reach the boat winches on the boat deck.

The lifeboats were stowed on hinged wood chocks on the boat deck, by groups of three at the forward and four at the after ends. On each side of the boat deck the cutters were arranged forward of the group of three and fitted to lash outboard as emergency boats.

They were immediately abaft the navigating bridge. The Engelhardt collapsible lifeboats were stowed abreast of the cutters, one on each side of the ship, and the remaining two on top of the officers' house, immediately abaft the navigating bridge.

The boat equipment was in accordance with the board of trade requirements. Sails for each lifeboat and cutter were supplied and stowed in painted bags.

Covers were supplied for the lifeboats and cutters, and a sea anchor for each boat. Every lifeboat was furnished with a special spirit boat compass and fitting for holding it; these compasses were carried in a locker on the boat deck. A provision tank and water beaker were supplied to each boat.

Compasses -— Compasses were supplied as follows:

  • One Kelvin standard compass, with azimuth mirror on compass platform.
  • One Kelvin steering compass inside of wheelhouse.
  • One Kelvin steering compass on captain's bridge.
  • One light card compass for docking bridge.
  • Fourteen spirit compasses for lifeboats.

All the ships' compasses were lighted with oil and electric lamps. They were adjusted by Messrs. C. J. Smith, of Southampton, on the passage from Belfast to Southampton and Southampton to Queenstown.

Charts — All the necessary charts were supplied

Distress Signals — These were supplied of number and pattern approved by Board of Trade— i. e., 36 socket signals in lieu of guns, 12 ordinary rockets, 2 Manwell Holmes deck flares, 12 blue lights, and 6 lifebuoy lights.

Pumping Arrangements

Midship Section of the Titanic, Showing Single Skin above Double Bottom, and Absence of Longitudinal Bulkheads

Midship Section of the "Titanic," Showing Single Skin above Double Bottom, and Absence of Longitudinal Bulkheads. Popular Mechanics Magazine (June 1912) p. 804-a. GGA Image ID # 10819412ed

The general arrangement of piping was designed so that it was possible to pump from any flooded compartment by two independent systems of 10-inch mains having cross connections between them.

These were controlled from above by rods and wheels led to the level of the bulkhead deck. By these it was possible to isolate any flooded space, together with any suctions in it.

If any of these should happen accidentally to be left open, and consequently out of reach, it could be shut off from the main by the wheel on the bulkhead deck. This arrangement was specially submitted to the Board of Trade and approved by them.

The double bottom of the vessel was divided by 17 transverse water-tight divisions, including those bounding the fore and aft peaks, and again subdivided by a center fore-and-aft bulkhead, and two longitudinal bulkheads, into 46 compartments.

Fourteen of these compartments had 8-inch suctions, 23 had 6-inch suctions, and 3 had 5-inch suctions connected to the 10-inch ballast main suction; 6 compartments were used exclusively for fresh water.

The following bilge suctions were provided for dealing with water above the double bottom, viz, in No. 1 hold two 3 ½ inch suctions, No. 2 hold two 3 ½ inch and 2 3-inch suctions, bunker hold, two 3 ½ inch and two 3-inch suctions.

The valves in connection with the forward bilge and ballast suctions were placed in the firemen's passage, the water-tight pipe tunnel extending from No. 6 boiler room to the after end of No. 1 hold.

In this tunnel, in addition to two 3-inch bilge suctions, one at each end, there was a special 3^inch suction with valve rod led up to the lower deck above the load line, so as always to have been accessible should the tunnel be flooded accidentally.

  • In No. 6 boiler room there were three 3 ½ inch, one 4 ½ inch, and two 3-inch suctions.
  • In No. 5 boiler room there were three 3 ½ inch, one 5-inch, and two 3-inch suctions.
  • In No. 4 boiler room there were three 3 ½ inch, one 4 ½ inch, and two 3-inch suctions.
  • In No. 3 boiler room there were three 3 ½ inch, one 5-inch, and two 3-inch suctions.
  • In No. 2 boiler room there were three 3 ½ inch, one 5-inch, and two 3-inch suctions.
  • In No. 1 boiler room there were two 3 ½ inch, one 5-inch, and two 3-inch suctions.
  • In the reciprocating engine room there were two 3 ½ inch, six 3-inch, two 18-inch, and two 5-inch suctions.
  • In the turbine engine room there were two 3 ½ inch, three 3-inch, two 18-inch, two 5-inch, and one 4-inch suctions.
  • In the electric engine room there were four 3 ½ inch suctions.
  • In the storerooms above the electric engine room there was one 3-inch suction.
  • In the forward tunnel compartment there were two 3 ½ inch suctions.
  • In the water-tight flat over the tunnel compartment there were two 3-inch suctions.
  • In the tunnel after compartment there were two 3 ½ inch suctions.
  • In the water-tight flat over the tunnel after compartment there were two 3-inch suctions.

from “How to save a big ship from sinking – p 92

Main drive centrifugal bulkhead salvage pumps for large ships with bulkhead forming one side of pumps and pipes

Electrical Installation

Fig. 126: Main Feeder Swichboard

Fig. 126: Main Feeder Swichboard. The Shipbuilder (Midsummer 1911) p. 112. GGA Image ID # 10dd72f3e9

Main Generating Sets —There were four engines and dynamos, each having a capacity of 400 kilowatts at 100 volts and consisting of a vertical three-crank compound-forced lubrication enclosed engine of sufficient power to drive the electrical plant. The engines were direct-coupled to their respective dynamos.

These four main sets were situated in a separate water-tight compartment about 63 feet long by 24 feet high, adjoining the after end of the turbine room at the level of the inner bottom.

Steam to the electric engines was supplied from two separate lengths of steam pipes, connecting on the port side to the five single ended boilers in compartment No. 1 and two in compartment No. 2, and on the starboard side to the auxiliary steam pipe which derived steam from the five single-ended boilers in No. 1 compartment, two in No. 2, and two in No. 4.  By connections at the engine room forward bulkhead steam could be taken from any boiler in the ship.

Auxiliary Generating Sets-—In addition to the four main generating sets, there were two 30-kilowatt engines and dynamos situated on a platform in the turbine engine room casing on saloon deck level, 20 feet above the water line. They were the same general type as the main sets.

These auxiliary emergency sets were connected to the boilers by means of a separate steam pipe running along the working passage above E deck, with branches from three boiler rooms, Nos. 2, 3, and 5, so that should the main sets be temporarily out of action the auxiliary sets could provide current for such lights and power appliances as would be required in the event of emergency.

Electric Lighting —The total number of incandescent lights was 10,000, ranging from 16 to 100 candlepower, the majority being of Tantallum type, except in the cargo spaces and for the portable fittings, where carbon lamps were provided. Special dimming lamps of small amount of light were provided in the first-class rooms.

Electric heating and power and mechanical ventilation

Fig. 128: Electric Heater

Fig. 128: Electric Heater. The Shipbuilder (Midsummer 1911) p. 113. GGA Image ID # 10de3c34fc

Altogether 562 electric heaters and 153 electric motors were installed throughout the vessel, including six 50-hundredweight and two 30-hundredweight cranes, four 3-ton cargo winches, and four 15-hundredweight boat winches. 

There were also four electric passenger lifts, three forward of the first-class main entrance and one in the second-class forward entrance, each to carry 12 persons.

Fig. 135: Loud-Speaking Telephone

Fig. 135: Loud-Speaking Telephone. The Shipbuilder (Midsummer 1911) p. 117. GGA Image ID # 10df4cc8bd

Telephones —Loud speaking telephones of navy pattern were fitted for communication between the following:

  • Wheelhouse on the navigating bridge and the forecastle.
  • Wheelhouse on the navigating bridge and the lookout station on the crow's nest.
  • Wheelhouse on the navigating bridge and the engine room.
  • Wheelhouse on the navigating bridge and the poop.
  • Chief engineer's cabin and the engine room.
  • Engine room and Nos. 1, 2, 3, 4, 5, and 6 stokeholds.

These were operated both from the ship's lighting circuit, through a motor generator, and alternatively by a stand-by battery, which by means of an automatic switch could be introduced in the circuit should the main supply fail.

There was also a separate telephone system for intercommunication between a number of the chief officials and service rooms, through a 50-line exchange switchboard.

Fig. 136: Telephone Exchange Switchboard

Fig. 136: Telephone Exchange Switchboard. The Shipbuilder (Midsummer 1911) p. 118. GGA Image ID # 10df529f1e

A number of the pantries and galleys were also in direct telephonic communication.

Wireless Telegraphy

The wireless telegraphy system was worked by a Marconi 5-lalowatt motor generator. The house for the Marconi instruments was situated on the boat deck close to the bridge.

There were four parallel aerial wires extended between the masts, fastened to light booms; from the aerials the connecting wires were led to the instruments in the house.

There were two complete sets of apparatus, one for the transmitting and one for receiving messages, the former being placed in a sound-proof chamber in one corner of the wireless house.

There was also an independent storage battery and coil, in event of the failure of the current supply, which came from the ship's dynamos.

Submarine Signaling —The Submarine Signal Co.'s apparatus was provided for receiving signals from the submarine bells. Small tanks containing the microphones were placed on the inside of the hull of the vessel on the port and starboard sides below the water level, and were connected by wires to receivers situated in the navigating room on the port side of the officer's deck house.

Various —The whistles were electrically actuated on the Willett Bruce system. The boiler-room telegraphs, stoking indicators, rudder indicators, clocks and thermostats were also electrical. The water-tight doors were released by electric magnets.

Emergency Circuit —A separate and distinct installation was fitted in all parts of the vessel, deriving current from the two 30-kilowatt sets above mentioned, so that in the event of the current from the main dynamos being unavailable an independent supply was obtainable.

Connected to the emergency circuit were above 500 incandescent lamps fitted throughout all passenger, crew, and machinery compartments, at the end of passages, and near stairways, also on the boat deck, to enable anyone to find their way from one part of the ship to the other.

The following were also connected to the emergency circuit by means of change-over switches: Five are lamps, seven cargo and gangway lanterns, Marconi apparatus, mast, side, and stern lights, and all lights on bridge, including those for captain's, navigating, and chart rooms, wheelhouse, telegraphs and Morse signaling lanterns, and four electrically-driven boat winches.

These latter, situated on the boat deck, were each capable of lifting a load of 15 hundredweight at a speed of 100 feet per minute.

Ventilating —There were 12 electrically-driven fans for supplying air to the stokeholds, 6 electrically-driven fans for engine and turbine room ventilation. There were fans for engine and boiler rooms.

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