Let's take a brief look at current day watertight doors in action.
Current Day Example
The Titanic
On April 10, 1912, the R.M.S. Titanic set sail across the North Atlantic Ocean, from Southampton to New York. She was thought to be unsinkable, but sank on April 15, the Titanic sank after colliding with an iceberg. Over 1,500 passengers and crew died.
The Titanic’s innovative watertight compartments were one of the main reasons she was considered unsinkable. The hull was separated into 16 watertight compartments using heavy duty centrally controlled watertight doors. The ship could stay afloat with up to four compartments flooded.
However, the compartments were not watertight, as they did not possess a roof section. They were like a jar without a lid, and after hitting the iceberg, water began flooding the vessel's forward six compartments. The bulkheads were not tall enough to contain the water, and in just over two and a half hours, the Titanic filled with water and sank.
Scientific American images and article from 1912 reprinted for 100 year anniversary.
Chapter 6: Watertight Bulkheads, Doors and Coal Bunkers
Watertight subdivision - The watertight subdivision of Titanic was considered very comprehensive at the time of her building. The design was such that that any two main compartments could be flooded with the ship loaded to the maximum load draft without affecting the safety of the ship. The minimum freeboard the vessel would have in the event of any two compartments being flooded was between 2'-6" and 8 feet from the deck adjoining the top of the watertight bulkheads (known as the “bulkhead deck”). In Titanic, any three of the four forward compartments could have been flooded without sinking the ship to the top of her lowest watertight bulkheads. The ship would remain afloat even with the four forward compartments flooded in a relatively calm sea; however, in heavy seas the water would have been encouraged to run along the decks aft of the forward bulkheads, finding its way below into the fifth compartment aft through the various non-watertight openings within the decks. Even in this state, survival of the ship would still be possible, providing the rate of flooding was not beyond the capabilities of the bilge pumps. . . (continued)
http://www.theory.physics.ubc.ca/titanic/
Ever since James Cameron's blockbuster movie Titanic, there has been much debate over whether or not there was a watertight door indicator panel. This panel, as seen in the movie, would have individual lights that would light up as the automatic watertight doors closed.
It is commonly believed, and accepted, by Titanic experts, that such a device was never installed on the Olympic, before 1913, and as such, one was never installed on the Titanic either. This belief is furthered by testimonial evidence presented during the US Inquiry into the loss of Titanic. On day four, Third Officer Pitman, would be asked about the presence of such a device.
Senator Smith: All right; I just wanted to know if you knew about it of your own knowledge. Is there any way for an officer on watch to tell whether the doors actually close when he works the lever from the bridge?
Pitman: No; I do not think there is.
Senator Smith: In order to have a perfect test, it would be necessary to have some one below, would it not?
Pitman: I can not say; I am not very well acquainted with those watertight doors. It is the first time that I have been with them
Senator Smith: Did you ever operate a lever on a door of a watertight compartment.
Pitman: From the bridge?
Senator Smith: Yes.
Pitman: No, sir; never.
Senator Smith :But it stands to reason, and your judgment as a navigator is, that operating the lever from the bridge you can not tell with exactness whether the doors have closed below or not?
Pitman: No. Anyhow, the watertight doors were of very little assistance this time.
On day seven, Quartermaster Olliver would also be questioned about the topic.
Senator Burton: Was there an instrument there to show the doors as they closed? Did you ever see one of those instruments?
Olliver: No; I never saw one.
Senator Burton: With little lights that burn up as each door closes, and then go out?
Ollliver: No, sir.
Senator Burton: There was no instrument like that on the Titanic?
Olliver: I did not see that.
Senator Burton: Would you have seen it if it had been there?
Olliver: No doubt I would, sir.
As can be seen, neither Olliver nor Pitman relate having seen such a device. Being that both men worked on the bridge, it seems reasonable that, had there been one, they would have known about it.
Research shows that after Olympic's maiden voyage, Chief Engineer Bell (who would later go on to be Chief Engineer of Titanic, and lose his life), would make the following remark, “I consider that a “tell tale” indicating on the bridge when the doors are closed would be an improvement.”i This at least suggests that Olympic did not have a light panel indicator, at least on its 'bridge', during its maiden voyage. Would Bell have made such a suggestion if there was one elsewhere? Under such suggestion would White Star have ignored it and not install one on Titanic? If Bell's suggestion did fall on deaf ears, the question would be why?
It may be because Titanic's watertight door system was state of the art back then. Titanic was fitted with twelve automatic closing watertight doors on its tank top level. The doors where, “A heavy cast iron door sliding in a heavy cast iron frame, the two being carefully machined and the frame having wedges on it so that when the door was lowered it was wedged home and the two machined faces coming together were made watertight,” and were, “arm controlled from four positions. Electrically, from the bridge, by hand, from the deck at the top of the bulkheads; by hand, adjacent to the doors, and by a float under the floors.”ii Via the bridge, there was no way to work the doors independently of one another.
These doors were designed by Harland and Wolff and constructed within the shipping yard. They were taken from a design developed by Nordeutscher Lloyd, a German company. The importance of the design was the fact that the doors not only closed with their own weight, due to the fact that they closed vertically, but they also did not need manual assistance, which in the past proved to be unreliable. Each door once activated would close in roughly twenty to thirty seconds due to oiled cataracts which governed their speed, operated by hydraulic power generated by two compressors, which worked at a constant pressure of 800psi. Edward Wilding would explain:
In order to give time after the automatic release from the bridge or by the float, so that no one coming through the door, or just passing through the door, should be injured, a hydraulic cataract cylinder, something like a gun recoil cylinder, was arranged, so that the earlier part of the drop shall be comparatively slow, depending on the leakage of a fluid back past the piston in the cylinder. To the last 18 inches or 2 feet there is a bye -pass round the piston, and the door is practically free to fall quickly just for the last 2 feet or so.iii
Due to the fact that these doors closed under their own weight, it was apparently felt that the system was fail safe, and it did not require the bridge knowing whether the doors had closed or not. Though this seems haphazard, it should be remembered that this very system lead to the belief that the ship was 'practically unsinkable'.
The location of the activation 'switch' or 'lever' (as it was referred to in the testimonies) has also been under much discussion. Olympic's switch, it is believed, was located in the chartroomiv. A 1913 notebook from a Harland and Wolff worker, has an entry dated March 1913, that states, “Closing doors also operated from Captain's Bridge. Tell-tale indicator on bridge for each door show whether closed.” The reader may have noted the mention that Olympic's doors were operated from the 'Captain's Bridge' and not the chartroom. Was the switch or lever moved? Or have historians mistaken the placement of the switch?
This is important, as Mr. Boyle, Surveyor in Chief, of the Board of Trade, when asked to give evidence for the bulkhead committee, would, in his draft of suggestions on shipbuilding, write:
Indicators: Indicators for showing when the doors are closed are most desirable. Some arrangements provide for the indicator being placed in the chartroom. v
Scribbled, as a side note, next to the suggestion, it reads: 'Central Control Gears do this'. This reference to 'central control' is in reference to the type of watertight doors that can be activated from a central location (i.e. the bridge) .
Such panels being located in the chart room is also suggested in the 1912 publication, Popular Electricity and the World's Advance, Vol. 5, issue 1-6. In issue five, published in September, 1912, is the article, Electricity's Part in Safeguarding Sea-Travel, which talks about the Titanic disaster. It states:
Of the services performed by electricity incident to safeguarding life at sea, there is none more important, perhaps, than the operation of the watertight bulkhead doors which may be operated individually or collectively from the bridge of the vessel. In this connection it may be mentioned that there has lately been inaugurated an agitation in favor of making these doors smaller in order that they may be more easily operated. In the latest approved system of electrically operated bulkhead door an electric bell sounds in each compartment that is to be closed for some seconds before the doors close, in order to allow time for the egress of any persons who may be in the compartments. Electric indicators in the chart house or on the bridge also indicate at all times just which doors are closed and which are open.
Though this in no way determines rather or not Titanic had such a device, it does suggest a possibility that, if anything, such a device was located in the chartroom if not on the bridge. As mentioned, Olympic's watertight door lever may have been located in it's chartroom. Could the suggestion for improvement, made by Chief Engineer Bell, actually have been to have a light indicator panel moved, and not necessarily have one installed?
Unfortunately, suggestions and indications seems to be all that we have. That is until now! In this debate it was once stated, “I can't prove ... that a system didn't exist, because I can't dig up proof of something's non-existence, short of having a witness or publication specifically state that the system wasn't there.”vi However, finally there is evidence that one did exist!
While researching into a question posted on the Encyclopedia Titanica forumvii, this author stumbled upon the publication, Popular Electricity and the World's Advance, Volume 4, Issues 1-6viii. In issue three, dated July, 1911, is the article The Latest Leviathan and Its Electrical Equipment, by C.B. Edwards. Though published after Olympic's maiden voyage, on June 14, 1911, the article is clearly written before Olympic left Belfast on March 31, 1911, as it reads, “The Olympic, the largest vessel in the world is almost ready to leave her berth at Belfast.”
The four page article goes on to talk about all the electrical marvels of the Olympic. The one in which is of interest to this paper reads as such:
Attached to the wall of the navigating room a most important piece of apparatus is the electric indicator for the watertight bulkhead doors. This provides means of observing the closing of all the doors and stopping the inflow of water in case of collision. The doors are closed by hydraulic pressure and as they swing too, tiny electric lights within the indicator show exactly which doors are closed or open.
Profiles of the Titanic and its decks. (Records of District Courts of the United States, RG 21)
Fig. 1 WATERTIGHT DECK AT WATERLINE LIMITS INFLOW OF WATER
Fig. 2 HIGH BULKHEADS, WITHOUT WATERTIGHT DECK WOULD SAVE THE SHIP BUT PERMIT DEEP SUBMERSION
Fig. 3 SINKING BY THE HEAD; WATER FLOWING ALONG LOW BULKHEAD DECK AND ENTERING COMPARTMENTS THROUGH DOORS OR HATCHWAYS
Fig. 4 DOWN BY THE HEAD, BUT SAVED BY HIGHER BULKHEADS AND WATERTIGHT BULKHEAD DECK
Fig. 5 RELATIVE AREA OF FLOODING FROM SAME DAMAGE IN SHIPS,
"A" WITH DOUBLE SKIN; "B" WITH SIDE BUNKERS; "C" WITH A SINGLE SKIN.
TRANSVERSE BULKHEADS ON EACH SHIP
Diagrams Showing Protective Value of Transverse and Longitudinal Bulkheads, Watertight Decks,and Inner Skin
The bulkhead subdivision above described is all done in vertical planes. Its object is to restrict the water to such compartments as (through collision or grounding) may have been opened to the sea. As the water enters, the ship, because of the loss of buoyancy, will sink until the buoyancy of the undamaged compartments restores equilibrium and the ship assumes a new position, with the water in the damaged compartments at the same level as the sea outside. This position is shown in Fig. 2, page 57. It must be carefully noted, however, that this condition can exist only if the bulkheads are carried high enough to prevent the water in the damaged compartments from rising above them and flowing over the tops of the bulkheads into adjoining compartments.
In addition to lateral and longitudinal subdivision by means of vertical bulkheads, the hull may be further subdivided by means of horizontal partitions in the form of watertight decks—a system which is universally adopted in the navies of the world. For it is evident that if the ship shown in Fig. 2, page 57, were provided with a watertight deck, say at the level of the water-line, as shown in Fig. 1, page 57, the water could rise only to the height of that deck, where it would be arrested. The amount of water entering the vessel would be, say, only one-half to two-thirds of that received in the case of the vessel shown in Fig. 2.
If ships that are damaged below the water-line always settled in the water on an even keel, that is to say without any change of trim, the loss through collisions would be greatly reduced. But for obvious reasons, the damage usually occurs in the forward part of the ship, and the flooding of compartments leads to a change of trim, setting the ship down by the head, as shown in Figs. 3 and 4. If the transverse bulkheads are of limited height, and extend only to about 10 feet above the normal water-line, the settling of the bow may soon bring the bulkhead deck (the deck against which the bulkheads terminate) below the water. If, as is too often the case, this deck is not watertight—that is to say, if it is pierced by hatch openings, stair or ladder-ways, ventilator shafts, etc., which are not provided with watertight casings or hatch covers, the water will flow aft along the deck, and find its way through these openings into successive compartments, gradually destroying the reserve buoyancy of the ship until she goes down. The vessels shown in Figs. 3 and 4 are similar as to their subdivision, each containing thirteen compartments; but in Fig. 3 the bulkheads are shown carried only to the upper deck, say 10 feet above the water, whereas in Fig. 4 they extend to the saloon deck, one deck higher, or, say, 19 feet above the same point. Now, if both ships received the same injury, involving, say, the three forward compartments, a loss of buoyancy which would bring the tops of bulkheads in Fig. 3 below the surface, would leave the bulkheads in Fig. 4, which end at a watertight deck, with a safe margin, and any further settling of the ship would be arrested.
Ordinarily, it would suffice to carry the first two bulkheads at the bow and the last two at the stern to the shelter deck, terminating the intermediate bulkheads one deck lower. But whatever the deck to which the bulkheads are carried, care should be taken to make it absolutely watertight. Otherwise, as already made clear, the so-called watertight subdivision of the ship may, in time of stress, prove to be a delusion and a snare.
Although the longitudinal bulkhead, which is employed below the water-line, and chiefly in the holds and machinery spaces, is the least used, it is one of the most effective means of subdivision that can be employed. A certain amount of prejudice exists against it, on the ground that it confines the inflowing water to one side of the ship, causing it to list, if not ultimately to capsize. But this objection merely points the moral that all things must be used with discretion. A single longitudinal bulkhead, built through the exact centre of a ship, would invite a speedy capsize in the event of extensive injury below the water-line. The loss of the British battleship Victoria emphasised that truth many years ago. But longitudinal bulkheads, carried through the engine and boiler spaces, at the sides of the ship, are a most effective protection. Not only is each of the large compartments in the wider central body of the ship divided into three, but along each side is provided a row of comparatively small compartments, several of which could be flooded without causing a serious loss of buoyancy.
These bulkheads, built some 15 to 18 feet in from the side of the ship, not only form an inner skin for the ship, but they serve as the inner wall of the coal bunkers. They extend from the inner bottom to the under side of the lower deck, to both of which they are securely riveted, the joints being carefully caulked, to render them watertight. The space between the ship's side and the bulkhead is subdivided by transverse watertight partitions (see plan of Mauretania, Fig. 3, page 129), placed centrally between the main transverse bulkheads of the ship. A further and most effective means for protecting the buoyancy is to construct the ship with a double skin up to and preferably a few feet above the water-line. The inner skin should extend from the first bulkhead abaft the engine-room to the first or collision bulkhead, forward. This construction merely involves carrying the inner floor plating of the double bottom up the sides of the ship to the under side of the lower deck. As all merchant ships are built with a double bottom (see page 107), the cost of thus providing a double skin below the water-line is small in proportion to the security against flooding which it affords.
The description of the Titanic, published at the time of her launch, stated that any two of her adjoining compartments could be flooded without endangering the safety of the ship, and the question must frequently have occurred to the lay mind as to why the ability of the ship to sustain flooding of her interior was confined to two, and not extended to include three or even more compartments.
The ability to stand the flooding of two compartments only is not peculiar to the Titanic. It represents the standard practice which is followed in all passenger ships, the spacing and height of whose bulkheads is determined in accordance with certain stipulations of the British Board of Trade. These stipulations, as given by Prof. J. H. Biles of Glasgow University, in his book "Design and Construction of Ships," are as follows:
"A vessel is considered to be safe, even in the event of serious damage, if she is able to keep afloat with two adjoining compartments in free communication with the sea. The vessel must therefore have efficient transverse watertight bulkheads so spaced that when any two adjoining compartments are open to the sea, the uppermost deck to which all the bulkheads extend is not brought nearer to the surface of the water than a certain prescribed margin.
"The watertight deck referred to is called the bulkhead deck. The line past which the vessel may not sink is called the margin of safety line.
"The margin of safety line, as defined in the above report, is a line drawn round the side at a distance amidships of three-one-hundredths of the depth at side at that place below the bulkhead deck, and gradually approaching it toward the aft end, where it may be three-two-hundredths of the same depth below it."
By referring to the diagrams on page 66 showing the disposition of bulkheads on certain notable ships, it will be seen that, in the case of the Titanic, the application of the Board of Trade rule called for the extension of the bulkheads amidships only to the upper deck, which, at the loaded draft of 34 feet, was only 10 feet above the water-line! Compare this with the safe construction adopted by Brunel and Scott Russell over fifty-four years ago, who, in constructing the Great Eastern, extended all the bulkheads (see page 83) to the topmost deck, fully 30 feet above the water-line.
Closing, from the Bridge, All Watertight Doors Throughout the Ship by Pulling a Lever
Quoted from Mighty Girl site linked above.
Raye Montague - the Navy's 'hidden figure' - is presented with an award in this undated photograph.
Montague was the first person to design a U.S. Navy ship and served as the Program Manager of Ships (PMS-309) for the Naval Sea Systems Command Information Systems Improvement Program. As program manager, she was responsible for five field activities, comprising a staff of 250 people and was in charge of procurement and purchase of CAD/CAM equipment for 111,000 people.
Photo courtesy Raye Montague
https://www.doncio.navy.mil/CHIPS/ArticleDetails.aspx?ID=8937Photo courtesy Raye Montague