The purpose of the paper is to set forth the argument that Titanic grounded on an underwater shelf of the iceberg, compromising her double bottom structure. The combination of direct impact damage suffered along the ship’s bottom and subsequent racking damage which parted plates along her starboard side allowed enough water into the hull so that the internal subdivision was overwhelmed.
The definitions for nautical terminology of relevance to this discussion can be found in Appendix I.
Assumptions
For purposes of this discussion, it is assumed that Titanic was turning towards the iceberg at the time of collision and that her reciprocating engines were stopped. The rationale for this assumption is detailed in Appendix II.
Descriptions
A reference for Titanic’s structure and internal subdivision can be found in Appendix III. A physical description of the iceberg is detailed in Appendix IV.
Collision
The most significant aspect of Titanic's iceberg encounter was that most people on the ship did not realize anything particularly unusual or important had happened. The majority of passengers slept through the most fateful seconds of their lives. Aside from those located deep within the forward portion of the ship, no one felt a great impact, or heard a deafening roar. There was only a slight tremble or a distant noise:
"It is best described as a jar and a grinding sound. There was a slight jar followed by this grinding sound....then thinking it over it was a feeling as if she may have hit something with her propellers....There was a slight jar followed by the grinding--a slight bumping...naturally, I thought it was from forward...[the grinding noise] lasted a matter of a couple of seconds..."— C.H. Lightoller, Second Officer, Officer's Quarters
"Well, I did not feel any direct impact, but it seemed as if the ship shook in the same manner as if the engines had been suddenly reversed to full speed astern, just the same sort of vibration, enough to wake anybody up if they were asleep...Not as if she hit anything straight on - just a trembling of the ship." — Able Seaman Joseph Scarrott, Forecastle Head
"At the time of the collision I was awake and heard the engines stop, but felt no jar. My husband was asleep." — Emily Bosie Ryerson, Passenger, Cabin B-63
"I was dreaming, and I work up when I heard a slight crash. I paid not attention to it until I heard the engines stop." — C.E. Henry Stengel, Passenger, Cabin C-116
"There was just a small motion, but nothing to speak of." — Pantryman A. Pearcey, 3rd Class Pantry, F Deck
Anecdotal evidence of this nature is normally treated with deserved circumspection by forensic accident examiners. However, in this instance, we have more than a single random observation. Many of the eyewitness descriptions of the impact contain common key elements: the event lasted only a few seconds, there was no strong jolt, a faint noise (sometimes described as a grinding of metal) emanated from the bottom of the ship. Equally significant are the details that are universally lacking from eyewitness descriptions. There were no tales of people being flung from the upper bunks by the force of the crash. No first-class passengers were pitched headlong down the famous Grand Staircase. Tables remained upright and drinks did not spill in the smoking rooms. Overwhelming agreement of survivors was that the meeting of Titanic's 53,000 tons (displacement) of steel with probably hundreds of thousands of tons of ice was a soft event.
Ship collisions with icebergs are usually not soft events. Three days prior to Titanic's fatal accident, another ship ran into the same field of ice. The French passenger liner Niagara ran headlong into an iceberg on the evening of Thursday, April 11, 1912. That accident occurred while passengers were enjoying dinner. The result was devastating, if press accounts, such as the following from the New York Herald, can be believed:
Passengers were hurled headlong from their chairs and broken dishes and glass were scattered throughout the dining saloons. The next instant there was a panic among the passengers and they raced screaming and shouting to the decks..."I thought we were doomed," said Captain Juham yesterday. "At first I feared we had been in collision with another vessel as I hurried to the bridge. But when I saw it was an iceberg and that we were surrounded by ice as far as we could see through the fog, my fears for the safety of the passengers and the vessel grew....I am sure Captain Smith had a similar experience in practically the same locality when the Titanic went down." — New York Herald, April 17, 1912
Despite their hair-raising experience, all passengers aboard the French liner survived, and the ship made its way to port. Perhaps because of Niagara's survival, it has become fashionable to blame First Officer Murdoch for not hitting the berg squarely on the bow. This, of course, is not a practical solution for a deck officer, no matter the imagined benefits. The discussion about a head-on collision, though, brought out an interesting point about the effect of a collision against the bow of a large ship, such as Titanic. Edward Wilding, the senior Naval Architect under Thomas Andrews at Harland & Wolff, testified during the British Board of Trade (BOT) Enquiry that in the case of a head-on collision, the bow of Titanic would have deformed much like the "crumple zone" of a modern automobile. This crumpling would have dissipated much of the force of the blow by spreading it out over several seconds. According to Wilding, telescoping of the ship in this manner would have reduced injuries among passengers and crew who were lucky enough not to have been trapped in the compacted sections of the bow.
While less dramatic than a head-on impact, the more-often invoked "glancing blow" at 22.25 knots would have created its own kind of havoc. At impact, the deck would have jumped sideways relative to anything not riveted to it. This "rebound effect" would have been as disruptive to people in the forward third of the ship as a major earthquake is in a large hotel ashore: sleeping third-class passengers in the bow would have been tossed out of their bunks; personal items would have been sent flying; people walking in the corridors would have been thrown to the deck. Either type of impact — head-on or glancing — would have been an unforgettable experience. None of the more than seven hundred survivors recalled such a dramatic event. Except for the men in the stokeholds, the survivors recalled the accident as a slight tremble of the ship...a distant rumble.
What a sailor might call "rebound" is otherwise known as "impulse and momentum." The sideswipe scenario envisions the hull striking the ice, then rebounding to strike again... and again...for nearly 300 feet along the bow. Second Officer Charles Lightoller’s description of the collision in his 1935 autobiography is typical of the view held by most:
"The impact flung her bow off, but only by the whip or spring of the ship. Again she struck, this time a little further aft. Each blow stove in a plate, below the water line, as the ship had not the inherent strength to resist." — Charles H. Lightoller, The Story of the Titanic, 1935
In theory, Titanic could have been so unlucky that her side was thrown against an underwater ram with exactly enough force to significantly deform her steel shell plating, but not enough force to throw people out of bed. This seems highly unlikely, though, considering that the ship maintained 21 knots or more throughout the collision event. More typically, a single sideswipe impact oftentimes produces a substantial hole at the point of contact, with little damage elsewhere.
If the ship did not sideswipe the berg, though, what could account for the damage so obviously suffered? It is the contention of the authors that Titanic struck on an underwater shelf of the iceberg as she attempted to port around the portion that was visible above the surface. In other words, Titanic grounded briefly on the ice.
"...It seemed almost as if she might clear it, but I suppose there was ice under water." — Lookout Reginald Lee, Crow’s Nest
Grounding
Titanic's bow featured a distinct cutaway at the forefoot (Fig. 7). The keel member was straight beneath the engine spaces and boiler rooms. Just forward of bulkhead "B," it began to rise at approximately a 14 degree angle until it met the forefoot at the stem. As will be shown, the significance of this design is that Titanic did not attain its full draft until the after end of Hold #1, just before bulkhead "B." A grounding event would have brought two wedge shapes into contact: the ship’s angled forefoot and the sloping underwater portion of the iceberg. There would be no hard impact of a vertical wall of steel against ice. Instead, the initial contact would have been lessened by the shapes of the objects involved. Titanic's forefoot rose at about a 14 degree angle so that beneath bulkhead "A" at frame 140, it was about 8' 4" above the depth of the keel. For this reason, the bottom along the forefoot would have absorbed just a small fraction of the ship's weight during the first instant of contact. As the wedge shapes of the hull and berg came into full contact, the steel hull pressing against the ice would have immediately crushed the softest portions of the ice, revealing the harder core underneath. Sliding onto mud or sand may produce almost no sound or vibration…river barge operators may not notice their tows are aground until forward progress virtually disappears. In this case, the action of Titanic’s steel hull striking the hard core of the ice surface can produce a sound like marbles pouring over sheet tin, or links of chain running out the hawsepipe:
"I was just sitting on the bed, just ready to turn the lights out. It did not seem to me that there was any very great impact at all. It was just as though we went over a thousand marbles. There was nothing terrifying about it..."
Mrs. J. Stuart White, Passenger, Cabin C-32
"What awakened me was a grinding sound on her bottom. I thought at first she had lost her anchor and chain, and it was running along her bottom." — Lookout George Symons, Crew’s Quarters ("up forward")
"A noise; I thought the ship was coming to anchor." — 3rd Officer Pitman, Officers’ Quarters
Grounding pressure would have been relatively light as the sloping forefoot met and then rode across the underwater portions of the iceberg. At frame 118, some ten feet ahead of bulkhead "B," the situation changed. The slope of the forefoot ended and the straight line of the ship's keel began. Logically, it would be at this point that Titanic would have felt full grounding pressure. Additionally, there should have been some greater shock to the ship's structure as this portion of the hull passed onto the ice:
"I felt as though a heavy wave had struck our ship. She quivered under it somewhat. If there had been a sea running, I would simply have thought it was an unusual wave which had struck the boat." — Maj. Arthur C. Peuchen, Passenger, Cabin C-104
"During the time she was crushing the ice, we could hear a grinding noise along the ship's bottom." — Quartermaster Robert Hitchens, Wheelhouse
"It was not a violent shock…not a bad jar…a rumbling noise…for about 10 seconds; somewhere about that…" — Able Seaman W. Brice, outside Seaman’s Mess Room
"…there was a kind of shaking of the ship and a little impact, from which I thought one of the propellers had been broken off." — Steward George F. Crowe, approximately 50 feet forward of amidships, E Deck
Sliding across the underwater ice ram could have lifted the starboard side of Titanic to some small extent. This lifting might have been virtually unnoticeable inside the hull on the lower passenger decks. On the other hand, the 90-foot height of the crow’s nest was the best place to detect a slight roll of the ship:
"...The ship seemed to heel slightly over to port as she struck the berg...very slightly to port as she struck along the starboard side." — Lookout Reginald Lee, Crow’s Nest
It appears that First Class passenger Hugh Woolner may also have noticed the slight lifting of the starboard side as the ship rode over the ice. Woolner was in the First Class Smoking Room at the time of the accident:
"We felt it under the smoking room. We felt a sort of stopping, a sort of, not exactly shock, but a sort of slowing down; and then we sort of felt a rip that gave a sort of a slight twist to the whole room." — Hugh Woolner, Passenger, 1st Class Smoking Room
Grounding of the Queen Elizabeth 2
It is as-yet impossible to confirm or deny the assertion that Titanic effectively grounded on an underwater ice shelf from an examination of the wreck. Because the bow portion stands upright and buried in the sediment, Titanic’s bottom is well hidden from view. To find support for the theory, the authors looked to other mishaps for similarities. One incident in particular involved a large liner that was running at high speed when she struck an underwater obstacle. The eyewitness descriptions given relating to the character of the impact of that mishap closely matches those given in the wake of the Titanic disaster. In 1992, the Queen Elizabeth 2 struck rocks 2.5 miles south of Cuttyhunk Island, Massachusetts, on her way to New York. At the time of the accident, the ship was making about 18 knots. Her bottom was ripped open by large boulders, but there was no violent impact. Just as in Titanic, the passengers of QE2 were not thrown about by the accident.
"The only thing I can compare it to, being from California, is a major earthquake." — Linda Robinson, Passenger, QE2
The passengers aboard QE2 were jostled more than their Titanic counterparts because the QE2 struck on hard rocks, instead of ice, which compacts on contact. Even so, as in Titanic, there were no injuries, no one was thrown to the deck, and panic did not ensue. According to the New York Times, passengers aboard the QE2 were more concerned about the re-opening of the ship's gambling casino than about whatever damage might have been suffered by the ship. The lesson taken from the QE2 mishap is that a grounding of a large passenger liner over a hard object at speed can still produce only a relatively mild impact.
Immediate Effects of the Grounding
Titanic's trip across the ice was anything but smooth, as descriptions of the impact when the ship came full upon the ice indicate. That first impact came just 11 feet forward of bulkhead "B" at the forward end of the Firemen's Passage. The weight and momentum of the ship must have worked in consort to cause upward movement of both the floor frames and the longitudinals in the bottom. Seventy-seven years after Titanic, the oil tanker Exxon Valdez struck Bligh Reef in Alaska's Prince William Sound. Shipyard workers who repaired that tanker's hull found numerous bent web frames and displaced longitudinals. Similar damage must have occurred to the framework of Titanic.
Referring to the Firemen’s Passage (lower centre of Fig. 1), it can be seen that upward deflection of the longitudinals forming the margin plates of the ballast tank in Hold #1 would have immediately been transmitted to the deck of the Firemen's Passage. This transfer damage would have caused displacement of the metal around the base of the circular stairways leading upward to the living quarters of the firemen and stokers. According to the British report, "...five minutes after the collision water was seen rushing in at the bottom of the firemen's passage on the starboard side." This is exactly the sort of flooding to be expected from a grounding. Displacement of the margin plates would have caused not only the Firemen's Passage to flood, but also the surrounding hold (Hold #2).
The official BOT report correctly linked the flooding of the tunnel and Hold #2, but somewhat implausibly attributed it to the iceberg somehow reaching deep inside the ship. In the "Description of/Extent of Damage" section of the report, it is stated that "...the ship's side was damaged abaft of bulkhead B sufficiently to open the side of the firemen's passage, which was 3 1/2 feet from the outer skin of the ship, thereby flooding both the hold and the passage." For this to happen, the ice would not only have to had penetrated the steel shell plating, but advance deeply enough into the hull to damage the passage standing away from the skin of the ship. In order to inflict this kind of damage, the ice spur had to have been dagger- or stiletto-shaped, thin enough to stay within the calculated opening size of approximately 12 square feet. In addition, the spur would had to have penetrated hull perpendicular to the hull surface (in other words, a puncture wound), as opposed to running parallel to the keel (as in a running rip or series of gashes). This runs counter to the known mechanics of the collision.
When Titanic first struck, the hull was probably nearly parallel with the long axis of the iceberg. However, the ship was not moving in a straight line. Titanic was making a right turn, which involved the overall advance and transfer of the vessel, as well as the pivoting of the bow toward the iceberg, in order to achieve Murdoch's goal of swinging the stern away. Presumably, the ice shelf on which Titanic grounded sloped upward to meet the upper portions of the berg above the waterline. This meant that as the ship's bow pivoted to her right, she had to push her way up the slope of the ice ram. From above, it would have appeared as if the ship's bow sideswiped the berg just as the well deck was passing. Indeed, some form of this interaction caused a significant amount of ice to break off the berg and deposit itself on Titanic’s forward well deck. As there is no evident collision damage to the upper works of the wreck from contact with the ice and no eyewitness reports of damage to the railings, mast or rigging, the exact manner in which this ice was dislodged to fall in the ship can only be surmised.
A standard "trick" for getting small ships away from a quay is to "push" the bow against an upright while motoring forward with the helm toward the quay (this trick would work with large ships, but it is hard to find uprights of sufficient size and strength). Although Murdoch did not plan to do this maneuver, that is exactly what he accomplished. Contact between the side of the ship and the berg helped pivot Titanic's stern well clear. This rapid pivoting also brought the forepeak into contact with the iceberg, just before the hull slid sideways off of the ice ram. By the time the iceberg came abreast of Boiler Room #6 (slightly abaft of the bridge), the ship was free. Possibly, the full weight of the ship was sufficient to break the ledge on which Titanic was riding, or the geometry of the intercept was such that she quickly rode off the edge of the berg. The whole accident from first to last touch had taken no more than 10 seconds and more likely 8 seconds, based on the time it would take a 22.3 knot vessel to travel approximately 300 feet.
Damage
It is not the purpose of this paper to discuss the overall damage to Titanic’s hull girder as a result of grounding upon an underwater ice shelf. However, in making the assertion that Titanic grounded on the berg, instead of the conventional view that she brushed against it, a variety of questions are raised regarding the damage immediately sustained during the collision (actually, the conventional collision scenario does not adequately explain how the forepeak and Firemen’s Passage were compromised, or the character of the collision as described by witnesses, but the burden of proof is always on the less conventional theory). The authors acknowledge that the type of damage expected as a result of a grounding accident must match the actual damage sustained by Titanic, as evidenced by eyewitness accounts and observations of the wreck. If grounding damage is not consistent with those realities, then the theory must be discarded. Two types of damage must be accounted for: (1) direct from the ice; and (2) racking of the hull.
Direct Damage
Sliding thousands of tons of steel across an underwater ice shelf must have caused a great deal of damage to the shell plating, as well as to the underlying frames and longitudinals. The first hard impact would likely have caused crushing of the double bottom. This damage can only be imagined, as it is confined to a portion of the ship that is not accessible with modern echo-sounding equipment. Photographs taken of QE2's bottom after her grounding give a hint of the type of punishment suffered by Titanic's more brittle shell plating. Much of this damage was likely inconsequential, because it would have simply opened to the sea the ballast tanks beneath the watertight tank top deck. The most serious direct damage flooding probably occurred at the after end of Hold #1 and the forward end of Hold #2 by way of bulkhead "B."
Steel Versus Ice
Since the discovery of the wreck in 1985, it has become possible to study the actual steel from which the ship was constructed. Samples of both the shell plate and the rivets which held the vessel together have subsequently been subjected to laboratory analysis. That analysis by Dr. Timothy Foecke of the Metallurgy Division, National Institute of Standards & Technology, and others, was conducted to test the assertion that Titanic's steel was "brittle" by modern standards for shipbuilding materials. The findings seem to indicate that the steel in Titanic's hull had adequate strength, but very low fracture resistance at (or near) the freezing temperature of seawater, which was the situation on the night of the disaster. However, there is not enough evidence to say that embrittlement played a significant role in the initial flooding of the ship.
The truth of what happened when ice met steel on April 14, 1912 must take into account the character of the ice itself. The impact of icebergs against iron or steel objects was investigated during the 1990s, during development of offshore oil drilling rigs for use on the Grand Banks. These experiments showed that the typical berg is a mixture of both soft and hard ice, and as such, presents a significant hazard to floating platforms. Dr. Stephen Bruneau of the Center for Cold Ocean Resource Engineering (C-CORE) in St. John's, Newfoundland, has stated that ice cubes in the normal home freezer (the kind used in soft drinks) are only about 10% as strong as steel. That would make them a poor adversary against a steel ship. However, ice deep inside a medium-sized iceberg, such as the one struck by Titanic, can be as cold as -25 degrees Celsius. At that temperature, the core of an iceberg is nearly ten times stronger than the average ice cube, strong enough to challenge the steel plate of an ocean liner. Typically, the crushing strength of ice is only about 1% that of steel.
Peter Wadhams is one of a group of present-day scientists who determined that solid ice below a berg's waterline is quite different from that projecting into the air above. His team found that the crystalline structure of submerged ice is much denser, with smaller trapped gas pockets. Individual ice crystals making up the underwater portion of a berg have also been found to be much larger and stronger than ice crystals exposed to the air. Conversely, the above-water portions are made of softer ice with larger gas pockets.
"While ice strength depends upon temperature, differences above and below the waterline would depend on the relative temperatures of air and water and the recent history of the iceberg with regard to rolling and calving. Steel is typically a lot stronger than ice. Most of the time very little happens when steel-hulled ships hit ice. Thin steel plating can be dented and the supporting frames bent. High speed vessel collisions have caused perforation of hulls that are not designed for ice impacts."
Dr. Richard McKenna, Ph.D., P. Eng,
Director of Ice Engineering for C-CORE
Based on Dr. McKenna's observations, and those of other researchers, certain generalizations can be formed for use in examining Titanic's collision with a medium-sized iceberg. The steel in the ship's hull was strong enough to withstand impact with the relatively softer ice often found above an iceberg's waterline. In addition, the ship's steel probably faired well against the high-speed impact that occurred. However, the colder (and therefore harder) ice found below the berg's waterline was much more likely to have caused damage to the ship. Significantly, a high-speed impact with an iceberg in this manner could explain the breach in Titanic’s shell plating and consequent flooding through the double bottom.
Racking Damage
As the ship rode across the ice ram, her bow would have been flexed upward in a manner never intended by its designers. This lifting would have been confined to the starboard side, which could have considerably racked the hull (Fig. 6). Movement of riveted plates against each other can cause the seams to lose watertight integrity, or shear the rivets, especially if the rivets were weakened by a significant slag content, as samples of Titanic’s have proven to be (refer to this Panel’s previously-published report, Titanic, The Anatomy of a Disaster). The former condition would only allow a slow seepage of water. The failure of a number of rivets along a horizontal seam, however, would have allowed a significant length of that seam to open, resulting in a large ingress of water.
Racking damage may also have caused the automatic watertight doors to close imperfectly. These cast iron doors slid vertically in tracks. Any distortion of those tracks would likely have caused a door of this design to stop their descent before closing the opening. Not only is deflection of the iron guides a possibility, but because the doors drop by gravity, their freefall is controlled by hydraulic arrestors. The entire door assembly is 16 feet tall from the bottom of the door sill to the top of the arrestors and the various components are not mounted on a common bed plate, but instead bolted directly to the bulkhead. The slightest deflection of the bulkhead out of plane will disturb the alignment of the arrestor rods, with the possibility of the door binding before reaching the bottom of its stroke. It is also important to note that there were no feedback circuits, so it was impossible for bridge personnel to determine whether or not the doors were secure. There is some evidence that the racking of the watertight door assembly in the vestibule at the aft end of the Firemen's Passage (Fig. 2) was a significant contributor for the loss of Titanic's sister ship, Britannic. The authors of this paper suggest that the failure of the automatic watertight door assembly in the Firemen's vestibule also contributed to the flooding in Titanic.
Damage by Compartment (Fig. 3)
Forepeak — not damaged during the initial grounding. The forepeak did not contact the ice until the ship came against the iceberg when the berg was approximately opposite hold #3. Sideways motion of the bow as it rotated to the right scraped the forefoot on the ice shelf at that time, causing the loss of watertight integrity to the peak tank. Water entering this tank was prevented from moving elsewhere inside the ship by bulkhead "A" and the lower Orlop deck.
Hold #1 — hold and tankage beneath were opened by crushing damage caused by hard impact with the ice. This impact took place approximately 11 feet ahead of bulkhead "B." Water was free to rise in Hold #1 to the Orlop deck, which was watertight except for the hatch tower to the forecastle deck.
Hold #2 — opened at forward end in way of bulkhead "B" by crushing damage caused by hard impact with the ice. Enclosure of firemen's stair tower displaced by upward movement of structure. Water flooded firemen's passageway, firemen's stair tower, and Hold #2. Water could rise in Hold #2 until it reached the Orlop deck, which was watertight. Above that level, it could rise in the hatch tower to the well deck. Water in the firemen's stair tower was free to rise to the level of G Deck, where it could flood the spaces in front of bulkhead "B" above Hold #1.
Hold #3 — may not have been opened directly by the ice. This hold would have been largely protected from direct contact by the double bottom. The turn of the bilge beneath the extension of the tank top deck covering the bilge brackets may have been damaged by crushing as the iceberg reached its closest point of approach. Flooding of mail room on the Orlop deck may have been caused by an open horizontal seam. If the automatic watertight door in bulkhead "D" did not fully close, then water in Firemen's Passage could have entered hold #3 through the open bunker doors located in the vestibule at head of Boiler Room #6 (see "Firemen's Passage" in Appendix III).
Note: The BOT report on the sinking suggests that water in Hold #3 had reached the height of 24 feet above the keel within the first ten minutes after the accident. This is based on the flooding of the mail room on the Orlop deck. However, an open seam in Hold #3 above the Orlop would have produced the same appearance, even if the hold beneath the Orlop deck was still essentially dry.
Boiler Room #6 — probably did not receive direct ice damage; instead, water entered through a seam in the shell plating opened by racking damage. The speed with which this compartment flooded has been disputed. Leading Fireman Barrett claimed at the BOT Enquiry that the water in the space was 14 feet above the tank tops inside of 10-15 minutes. However, quick flooding can be anticipated if the automatic watertight doors in the vestibule (see "Firemen's Passage" in Appendix III) did not fully close. Open seams, caused by the racking of the hull on the ice, likely contributed water to that entering this compartment from elsewhere.
Boiler Room #5 — only a small portion of a seam was reported opened, about 2 feet off the deck. This seam was apparently an extension of seam parting that began in Boiler Room #6 and continued across bulkhead "E" (water was also noted coming into the bunker separating the two compartments). Distortion of the supporting longitudinals might have compromised the integrity of bulkhead "E," leading to a subsequent failure along the starboard side.
Flooding resulting from a grounding would have immediately filled Holds #1 and #2. Water rising in the Hatch #1 tower would have caused the canvas cover to bulge upward and produce the sounds described by eyewitnesses. Water in Hold #2 was contained by the Orlop deck, but water rising in the stair tower quickly began to flood onto G Deck forward of bulkhead "B." This is the water that forced the greasers and firemen sleeping on G Deck to evacuate before midnight. If Boiler Room #6 was flooded as quickly as the BOT report indicates, the water likely came through partially-closed watertight doors in the vestibule at the after end of the Firemen's Passage. After midnight or so, secondary flooding through scuttles, hatches, ports and other ordinary openings in the liner's structure became the primary source of water.
Summary
Through a reassessment of First Officer Murdoch’s final maneuver, a compilation of eyewitness descriptions regarding the character of the collision, a revaluation of the damage reported by witnesses and observed on the wreck, the authors have come to the conclusion that Titanic grounded briefly on a projecting underwater shelf of the iceberg. This strike was hard enough to open portions of the hull’s double bottom to the sea and transmit shock damage up supporting members so that watertight integrity in the immediate area was compromised. In addition, as the ship’s momentum carried the starboard side of the hull up farther onto the shelf, racking damage distorted shell plating on the starboard turn of the bilge, shearing rivets and opening seams. Water entering from below and alongside the forward holds and boiler rooms eventually overcame the hull’s internal subdivision, causing the ship to founder.
Appendix I
Nautical Parlance
Although less than a century has passed since Titanic foundered, the everyday language of seaman has changed almost as much as their ships. A few key words or phrases used in the testimony can be misleading to modern readers, unless the contemporary meaning of the word is fully understood. Readers are cautioned in particular to read the following words with awareness of their 1912 connotations and denotation:
BILGE — In vessels with a double bottom, the triangular channel or waterway formed by the tank margin plate and the curvature of the outside shell. It runs fore and aft and is subdivided by the ship's transverse bulkhead system.
CRASH STOP — A modern phrase used in this paper to describe the use of the engines in reverse to perform an emergency stop. This term was not widely used in Titanic’s time (there is occasional reference to "crashing back" the engines), but the maneuver was, as evidenced by Titanic’s practice of it during her builder’s trials.
HARD A’STARBOARD; HARD A’PORT — Helm orders in 1912 that reflected a convention from the days when ships were steered by a tiller system. Ordering the helm to starboard is the equivalent of left rudder. This confusing system of helm orders existed in the British Merchant Marine until the 1930s.
STOP — An order to the engine room on the engine order telegraph to stop rotation of the propellers by stopping the engine. On modern ships, a STOP command usually only involves stopping the engine while allowing the propellers to windmill (a STOP SHAFTS command is used to apply steam to keep the shaft from rotating). An "all stop" order does not immediately cause the ship to come to a halt. The ship may coast forward for some distance.
STRIKE — From the International Maritime Dictionary, 2nd ed. by Rene De Kerchove: "A ship strikes when it in any way touches the bottom. To run ashore or aground. To run upon a bank, a shoal, and so on."
TOUCH — To graze the bottom of the sea with the keel for a moment with little, if any, lessening of the ship's forward speed.
Appendix II
STOP Command / "Porting Around" Maneuver
STOP Command
First Officer William Murdoch was a skilled shiphandler, with 9 complete voyages in Olympic constituting his most recent experience. He would have realized immediately upon seeing the iceberg that the starboard wing propeller would pass uncomfortably close, especially so if any of the ice extended towards the ship underneath the water. Slamming a spinning propeller against that ice would surely damage one or more of the starboard propeller blades, with possible transmitted shock damage to the respective shaft and engine. Similar damage recently suffered by Olympic during a collision less than two months previous with an underwater object quite possibly flashed through Murdoch’s mind as he weighed his options. The only practicable way to protect the starboard propeller and shaft was to stop the reciprocating steam engine that drove them. However, stopping only the starboard engine would result in an asymmetric thrust. The still-driving port propeller would tend to drive the bow to starboard, in opposition to the helm order Murdoch had just issued. The result would have been the head-on impact with iceberg that the first officer was trying to avoid. Only one option remained to protect the starboard propeller: stop all engines.
Fourth Officer Joseph Boxhall reported during the Enquiry that upon arriving on the bridge after the fact, he saw both telegraph handles pointing to FULL ASTERN, and heard Murdoch report that the engines had been reversed to Captain Smith. This, in effect, has led historians to believe that Murdoch rang down a "crash stop."
A crash stop, though, is the last thing that Murdoch would have wanted to perform to avoid the iceberg. Under full reverse power, the bow would not have pivoted to port as the lookouts described in their testimony. The stern would have begun kicking to starboard, and with forward momentum still a factor, the hull would have slewed toward the berg, almost out of control. In all probability, Titanic most probably would have ended up with her starboard beam up against the berg.
With the exception of Boxhall, crew testimony contradicts the assertion that the engines were crashed back. Greaser Frederick Scott was in the engine space. "I noticed ‘stop’ first," he told the British hearings, "on the main engines." Murdoch's orders came down on both the main engine and emergency order telegraphs: "All four went together: ‘stop.’ Two greasers at the bottom rang back. They were feeding the engines and were close handy at the time," Scott testified. Immediately afterward, the boiler telegraphed signaled STOP, telling the lead firemen to order the dampers shut on their furnaces. Leading stoker Frederick Barrett had been talking with Second Engineer James Hesketh when the lights on the stoking indicators changed from white (FULL) to red (STOP). Closing the dampers was an ordinary precaution to prevent generating excess steam pressure when rotation of the engines was stopped. In a crash back scenario, the boiler room telegraphs would be expected to remain unchanged at FULL.
The most positive proof that a crash stop never occurred is that not one of the more than 700 survivors remembered the rumbling and shuddering of the stern that would certainly have been part of such a maneuver.
"Porting Around" Maneuver
In the traditional version of Titanic's accident, the starboard bow just brushes the iceberg as the ship turns left, away from danger. The manner in which ships move in the water belies this assumption. Iceberg damage to the starboard bow would have necessitated bumping and grinding of the ice along the ship's starboard side all the way to the stern. Edward Wilding was the senior Naval Architect working for Thomas Andrews in the designing office at Harland & Wolff, Ltd. During his testimony before the Wreck Commission, Wilding pointed out the impossibility of the left-turn-only description of the accident:
MR. WILDING: After the ship had finished tearing herself at the forward end of No. 5, she would tend to push herself against the iceberg a little, or push herself up the iceberg, and there would be a certain tendency, as the stern came round to aft under the helm, to bang against the iceberg again further aft.
There are no reports of damage farther aft than boiler room #5. Nor are there reports of contact between the hull and the iceberg farther aft than the forward well deck. Titanic's starboard emergency boat was kept rigged outboard for immediate use. Although witnesses describe the top of the berg as extending above the boat deck, this boat was not touched. Nor were the four regular lifeboats, which had been swung outboard at the after end of the Boat Deck. All of this evidence is contrary to what would have been expected if the ship had, in Wilding's words, "banged against the iceberg again further aft."
According to the ship’s lookouts and helmsman, Titanic’s bow had already turned two points to port before the collision occurred. From this, we can assume that Titanic’s bow cleared the berg. In this situation, it would be expected that contact would have occurred near the hull’s pivot point, which was about one-third of the vessel's length from the bow. A port turn would likely have caused damage just forward of the pivot point and continue aft for the entire length of the ship. Instead, damage appears to have been confined to the very forward portion of the ship, with the amidships and stern area escaping any contact with the berg. The only possible reason for this apparent paradox is that First Officer Murdoch in fact completed his "port around" maneuver. The conventional story of the ship turning to its left and just scraping the starboard bow must be revised:
Titanic was turning to her right (port helm in 1912) when she struck on the ice.
To "port around" the iceberg, Murdoch used a common maneuver for power-driven vessels. First, he turned to port to clear the bow. Then, he shifted the helm to swing the stern away from the ice. This second turn required a "hard a’port" order to the quartermaster. Testimony from three crewmembers confirms Murdoch’s maneuver. The first was from Quartermaster Alfred Olliver, who was just walking into the enclosed section of the bridge as the iceberg was passing down the starboard side. He described what happened at the U.S. Senate Inquiry:
SENATOR BURTON: You do not know whether the helm was put hard astarboard first, or not?
MR. OLLIVER: No, sir I do not know that.
SENATOR BURTON: But you know it was put hard aport after you got there?
MR: OLLIVER: After I got there. Yes, sir.
SENATOR BURTON: Where was the iceberg, do you think, when the helm was shifted?
MR. OLLIVER: The iceberg was way up stern.
SENATOR BURTON: That is when the "hard aport" was given?
MR. OLLIVER: That is when the order "hard aport" was given. Yes, sir.
SENATOR BURTON: Who gave the order?
MR. OLLIVER: The first officer.
SENATOR BURTON: And that order was immediately executed?
MR. OLLIVER: Immediately executed, and the sixth officer saw that it was carried out.
Quartermaster George Rowe was stationed on the poop deck to tend the ship's taffrail log and be on the general lookout aft. In Rowe’s U.S. testimony, he states:
SENATOR BURTON: Could you hear the ice scraping along on the boat where you were?
MR. ROWE: No, sir.
SENATOR BURTON: So you do not know whether it was rubbing against the hull there or not?
MR. ROWE: No, sir.
SENATOR BURTON: What is your best judgement about that?
MR. ROWE: I do not think it was.
SENATOR BURTON: You are positive you heard no rubbing?
MR. ROWE: Yes, sir.
SENATOR BURTON: Do you not think that if the helm had been hard astarboard the stern would have been up against the berg?
MR. ROWE: It stands to reason it would, sir, if the helm were hard astarboard.
Another seaman, Joseph Scarrott, was smoking in the forecastle when the ship struck. He scrambled on deck near the bow, where he saw the berg gliding along the ship's starboard side. In London, he testified that Titanic was under port helm (turning right) and that the stern was swinging away from the ice. Passenger George Harder confirmed Scarrott’s observation from his cabin:
"...I heard this thump, then I could feel the boat quiver and could feel a sort of rumbling, scraping noise along the side of the boat. When I went to the porthole I saw this iceberg go by. The porthole was closed. The iceberg was, I should say, about 50 to 100 feet away."
The evidence indicates that First Officer Murdoch did attempt to "port around" the iceberg. He first turned the ship to port, in order to clear the bow. He immediately followed that with a turn toward the iceberg, in order to swing the stern away from danger. Between the two helm orders, he rang down STOP on both engines, in an attempt to protect the starboard propeller from damage.
When Titanic struck on the berg, she was turning to the right — toward the iceberg. The fact that Titanic ended up pointing north, when she had originally been heading west, could be taken as further corroboration of this assumption.
Appendix III
Physical Description of Titanic
The following description of the vessel is taken from the official British Board of Trade report on the disaster. Most of the details are familiar, but this information is provided for easy reference. For brevity and clarity, only those elements of the ship that are germane to this discussion have been included:
The Steamship "Titanic"
The "Titanic" was a three-screw vessel of 46,328 tons gross and 21,831 net register tons, built by Messrs. Harland and Wolff for the White Star Line service between Southampton and New York. She was registered as a British steamship at the port of Liverpool, her official number being 131,428. Her registered dimensions were: —
Length ... ... ... ... ... ... ... 852.5 ft.
Breadth .. ... ... ... ... ... ... 92.5 ft.
Depth from top of keel to top beam at lowest point of sheer of C. Deck, the highest deck which extends continuously from
bow to stern ... ... ... ... ...64 ft. 9 in.
Depth of hold .. ... ... ... ... ... 59-58 ft.
Displacement at 34 ft. 7 in. is .. . 52,310 tons.
Structural Arrangements – The structural arrangements of the "Titanic" consisted primarily of:—
(1) An outer shell of steel plating, giving form to the ship up to the top decks.
(2) Steel Decks – These were enumerated as follows:—
C, D, E and F were continuous from end to end of the ship. The decks below were continuous outside the boiler and engine-rooms and extended to the ends of the ship. Except in small patches none of these decks was watertight in the steel parts, except...the Orlop deck aft.
G deck, 190 ft. forward of boilers, 210 ft. aft of machinery
Orlop Deck, 190 ft. forward of boilers, 210 ft. aft of machinery
(3) Transverse Vertical Bulkheads – There were 15 transverse watertight bulkheads, by which the ship was divided into 16 separate compartments. These bulkheads are referred to as "A" to "P," commencing forward.
The Orlop deck abaft the turbine engine room and forward of the collision bulkhead was watertight. All the decks had large openings or hatchways in them in each compartment, so that water could rise freely through them.
The watertightness of bulkheads extended up to one or the other of the decks D or E; the bulkhead A extended to C, but was only watertight to D deck. Bulkheads A and B...further extended watertight up to the underside of D deck.
Bulkheads A and B forward, and P aft, had no openings in them. All the other watertight bulkheads had openings in them, which were fitted with watertight doors. Bulkheads D to O, both inclusive, had each a vertical sliding watertight door at the level of the floor of the engine and boiler rooms for the use of the engineers and firemen. On G deck there were no watertight doors in the bulkheads. On both the F and E decks nearly all the bulkheads had watertight doors, mainly for giving communication between the different blocks of passenger accommodation. All the doors, except those in the engine rooms and boiler rooms, were horizontal sliding doors workable by hand both at the door and at the deck above.
There were twelve vertical sliding watertight doors which completed the watertightness of bulkheads D to O inclusive, in the boiler and engine rooms. These were capable of being simultaneously closed from the bridge. The operation of closing was intended to be preceded by the ringing from the bridge of a warning bell.
Structure
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 in., except in way of the reciprocating machinery, where it was 78 in. For about half of the length of the vessel this double bottom extended up the ship's side to a height of 7 ft. 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 watertight compartments in the breadth of the vessel. Before and abaft the machinery space there was a watertight division at the centre line only, except in the foremost and aftermost tanks. Above the double bottom the vessel was constructed on the usual transverse frame system, reinforced by web frames, which extended to the highest decks.
The transverse strength of the ship was in part dependent on the 15 transverse watertight 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.
Watertight Sub-division.– 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 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 watertight flat, thus completing the watertightness of the compartment....By this sub-division there were in all 73 compartments, 29 of these being above the inner bottom.
Watertight doors.– The doors (12 in number) immediately above the inner bottom were in the engine and boiler room spaces. They were of Messrs. Harland and 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 electro-magnet controlled from the captain's bridge....The time required for the doors to close was between 25 and 30 seconds....The watertight doors on E deck were of horizontal pattern, with wrought steel door plates. Those on F deck ...were of similar type, but had cast iron door plates of heavy section, strongly ribbed. Each of the 'tween 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.
Double Bottom
Authors’ note: Although an apparently thorough description of the ship, the official Board Of Trade (BOT) report ignores some details of Titanic's construction that had a direct bearing on both the damage received from the collision with the iceberg and the eventual foundering of the vessel. The BOT report gives the impression that Titanic's double bottom was of uniform design. This is far from the case. Forward of bulkhead "D," Titanic did not have the same double bottom that existed beneath the boiler rooms and engine spaces. The tank top in holds #1, #2, and #3 ended well inboard of the actual shell plating (Fig. 4). The margin plates of the tankage extended downward at only a slight outward angle to the perpendicular. The tank top deck was not continued outward to meet the shell plating. In effect, this meant that instead of a double bottom, the forward holds had what amounted to internal ballast tanks somewhat reminiscent of the McIntyre system of ballast tanks that was already obsolete at the time of Titanic's construction. A key feature of Titanic's tankage beneath the forward holds is that the double bottom did not protect against ingress of water from damage to either the turn of the bilge or the side of the vessel.
Aft of bulkhead "D," the design approached a modern cellular double bottom. The margin plates still dropped nearly vertically to meet the horizontal bottom plating of the shell. However, the floor frames were extended outward by brackets which created the turn of the bilge. These brackets were riveted to the margin plate in way of the transverse floor frames. An extension of the tank top deck extended horizontally on top of these brackets to the shell plating (Fig. 5). Although the drawings do not say, presumably the wing tanks thus created at the turn of the bilge were watertight. The construction of Olympic, the lead ship of the class, was photographed just prior to the installation of the bilge brackets, which can be seen scattered along the length of the building floor of the Harland & Wolff yard.
Because the wing tanks continued the tank top to the shell plating above the turn of the bilge, the double bottom aft of bulkhead "D" did provide protection against ingress of water in either the bottom or at the turn of the bilge.
Firemen's Passage
A significant feature of the Olympic-class of ships was a "Firemen's Passage" and a vertical stair tower containing two circular stairways. This combination of stairs and tunnel allowed the ship's "black gang" to move from their quarters on D, E, F, and G decks to the stokeholds, without passing through the passenger accommodations.
...The firemen's passage, giving direct access from their accommodation to the forward boiler room by stairs at the forward end, contained the various pipes and valves connected with the pumping arrangements at the forward end of the ship, and also the steam pipes conveying steam to the windlass gear forward and exhaust steam pipes leading from the winches and other deck machinery. It was made thoroughly watertight throughout its length, and at its after-end was closed by a watertight vertical sliding door of the same character as other doors on the inner bottom. Special arrangements were made for pumping this space out, if necessary....
The design of this combined horizontal and vertical passageway demands closer inspection. Although not obvious in the ship's accommodation plan of the tank top, the firemen's passageway overhangs the underlying ballast tanks at the head end of hold #2. The walls of the tunnel are outboard of the margin plates of the tanks (Fig. 4). Both the tunnel and the stair tower were watertight, although the tower was watertight only to the upper side of G deck. There was one watertight door at the after end of the tunnel in way of bulkhead "D."
Most descriptions of the Firemen's Passage overlook the attached vestibule at the forward end of boiler room #6. This unusual space was in effect a 17th watertight compartment on the tank top level (Fig. 2). It had the dubious distinction of containing the most watertight doors of any compartment: four. The forward end of the vestibule was protected against flooding of the firemen's passage by the automatic watertight door already mentioned in bulkhead "D." There was an identical vertical sliding door at the after end of the vestibule that separated it from boiler room #6. Two manual watertight doors were also located in this tiny compartment. These were conventional hinged doors that led into the two reserve coal bunker spaces in hold #3. These bunker spaces were located to port and starboard of the firemen's passage, hence the need for two doors. A fifth opening in the vestibule was an escape tower that led to the upper side of F deck.
The stair tower at the forward end of the Firemen's Passage had no watertight closure on any deck. Due to an unusual design, this tower originates on the after side of bulkhead "B" on the tank top. On G deck, it is unexpectedly moved to the forward side of bulkhead "B." This was accomplished by a slight jog in that bulkhead. On the night of April 14-15, water rising in the stair tower did not flood Hold #2 as might be expected, but Hold #1 and all of the other spaces in the compartment forward of bulkhead "B."
Appendix IV
Physical Description of the Iceberg
One of the significant failings of research into the sinking of Titanic has been the lack of attention paid to the other large floating object involved: the iceberg. Yet the size, shape, density and hardness of that floating mountain of ice were all factors in creating the fatal damage to the ship. No honest assessment of the sinking can avoid the necessity of investigating the fatal iceberg.
The Size and Shape of Titanic's Iceberg
Icebergs come in a variety of sizes and shapes that vary with the locations where they were calved and their ages. No two icebergs have the same shape. Also, all icebergs are continually changing shape as they decompose by melting. Scientists who study icebergs have created descriptive names for bergs based on their characteristics:
Tabular – A flat-topped iceberg with steep or vertical sides. Most show horizontal banding. Very solid. Length to height ratio less than 5:1.
Blocky – A flat-topped iceberg with steep vertical sides.
Non-Tabular – This category covers all icebergs that are not tabular as described above. This includes bergs that are dome-shaped, sloping, blocky, and pinnacle.
Drydocked – An iceberg which is eroded so that a U-shaped slot has formed.
Pinnacled – An iceberg with a central spire, or with more than one spire.
Wedged – An iceberg that is flat on top and with steep vertical sides on one end and sloping on the other.
In addition to names describing their shapes, icebergs can also be described by their size. At the top on the size charts are the very large bergs that tower 46 to 75 meters above the water and are more than two football fields in length. The smallest true icebergs are growlers, which are less than a meter high and only 5 meters or so in length.
The berg in Titanic's path most likely broke off the Jacobshaven glacier on the west coast of Greenland. More than 85% of all the icebergs on the North Atlantic are thought to originate with that glacier or with the nearby Humbolt glacier. Approximately 40,000 medium- to large-sized bergs calve annually in Greenland. New bergs may spend a year or more in the waters of their berth before moving south through the Davis Strait. Seldom do more than 2% of them make it as far south as latitude 48 North. In April of 1912, however, a significant amount of ice had been carried much further south on the Labrador current. Titanic was a bit south of 42 North when it struck.
Icebergs from the Jacobshaven glacier have characteristically pointed shapes. There were few eyewitnesses to Titanic's iceberg. However, the descriptions that do exist seem to agree that the fatal iceberg had at least one towering point, and perhaps more. Quartermaster Thomas Rowe pacing Titanic's poop deck than night first thought he saw the masts and sails of a sailing ship. Another Quartermaster, Alfred Olliver, was not in a position to see any more than the highest portions of the iceberg. He described the "tip" of the berg gliding past where he walking on the Boat Deck. Lookout Frederick Fleet remembered the berg having a large, pointed top. On the morning after the tragedy, the chief steward on the German ship Prinz Adelbert snapped a picture of an iceberg with a large smear of red paint along the berg’s waterline. That iceberg had a large central point with two smaller flanking points. In the dark, it could have been confused for a moment with the three masts of a sailing ship.
No clear-cut evidence exists as to the horizontal length of the fatal iceberg. Estimates have ranged from 200 to 400 feet. This range is in keeping with the approximate 60 to 100 foot height estimates of eyewitnesses. When combined, it appears that Titanic was the victim of a rather ordinary medium-size iceberg. It was probably a pinnacle berg that had started to erode into the drydock configuration.
Underwater Shape
Icebergs float because the dense ice in their cores is less dense (about 900 kg per cubic meter) than sea water (about 1025 kg per cubic meter. When an iceberg is first calved, as much as 20% of it may extend above the waterline. The reason for this is that the upper portions are often comprised primarily of snow, which is much less dense (lighter) than the core of the berg. Icebergs are quite unstable. As a result, they roll over frequently during their lifetimes. After a few rolls, the middle-aged berg has lost its topping of snow, leaving only the dense, hard-frozen core. The result is that less berg is exposed above the waterline. Older bergs float with only about 1/8th of their bulk exposed to the air.
The most significant factor with regard to understanding what happened to Titanic is that icebergs are typically 20% to 30% longer under the water than above. Thus, a berg that has a length of 100 feet above the waterline can be expected to be 120 to 130 feet wide under the water. The sloping ice shelves that extend outward beneath the water pose a significant threat to ships operating near icebergs. This is made clear in H.O. Pub 9, The American Practical Navigator ("Bowditch"):
Another danger is from underwater extensions, called rams, which are usually formed due to melting or erosion above the waterline at a faster rate than below. Rams may also extend from a vertical ice cliff, also known as an ice front, which forms the seaward face of a massive ice sheet....In addition to rams, large portions of an iceberg may extend well beyond the waterline at greater depths.
American Practical Navigator, 1995
Icebergs are the subject of continuous study at the Center for Cold Ocean Resource Engineering (C-CORE) in St. John's, Newfoundland. Richard F. McKenna, Ph.D., P. Eng, is Director of Ice Engineering for C-CORE. He confirmed for the authors of this paper the dangers of ice rams or other underwater extensions of icebergs. "Iceberg shapes are highly irregular," he wrote. "From a technical standpoint, we are cautious about making conclusions from above water shapes. That said, underwater shapes are quite variable and underwater protrusions beyond the water line extend (rams) are quite common."
The practical aspects of handling ships around ice are also discussed in Bowditch. Vessel operators are cautioned that if they must make contact with an ice floe:
...never strike it a glancing blow. This maneuver may cause the ship to veer off in a direction which will swing the stern into the ice. If possible...hit it head-on at slow speed....
...Keep clear of corners and projecting points of ice, but do so without making sharp turns which may throw the stern against the ice, resulting in a damaged propeller, propeller shaft, or rudder. The use of full rudder in non-emergency situations is not recommended because it may swing either the stern or mid-section of the vessel into the ice.
American Practical Navigator, 1995
Although this advice comes from a recent navigation text (1995), the dangers of ice rams were well known in 1912. More specifically, they were well known to Captain Edward J. Smith, who was Master of Titanic on her fatal voyage. Eerily, the captain appears to have predicted Titanic's accident to some American friends, Mr. and Mrs. W. P. Wills, and a Dr. Williams in 1910. At that time, Smith was Master of the White Star liner Adriatic.
"...the big icebergs that drift into warmer water melt much more rapidly under water than on the surface, and sometimes a sharp, low reef extending two or three hundred feet beneath the sea is formed....If a vessel should run on one of these reefs half her bottom might be torn away....Some of us would go to the bottom with the ship."
Captain E.J. Smith, as quoted in The New York Times, April 18, 1912
Stability of Icebergs
One piece of universal advice to navigators is to avoid approaching icebergs because they have a tendency to capsize with little or no warning. "It is dangerous to approach an iceberg because it can calve or roll, creating a huge disturbance in the water which can upset a boat," is the warning from Dr. Stephen E. Bruneau, Ph.D., P. Eng. of Tatham Offshore Canada Ltd., Bain Johnston Centre in St. John's, Newfoundland. According to Dr. Bruneau, "It is even more dangerous to attempt to get on an iceberg. Falling ice is a threat and a rolling berg can dump you in the very cold water before collapsing over on top of you."
The notorious instability of icebergs is the result of their random shapes, coupled with non-uniform melting that can cause bergs to suddenly reorient themselves in the water. Another cause of rolling is a large portion of the berg breaking off to form a growler. Tabular icebergs are considered the most stable. The least stable are dome and wedge-shaped berges, which can roll over within seconds for no apparent cause.
Color of Icebergs
Icebergs that originate in Greenland are comprised of compacted snow. It is estimated that this compaction takes 10,000 to 15,000 years to accomplish. The resulting ice is full of tiny air bubbles, which reflect sunlight, giving icebergs their characteristic white color. Blue bands are usually the result of meltwater that has re-frozen and is bubble-free. Ice that does not have trapped air is bluish in color. Dark streaks through an iceberg can be caused by dirt and rocks picked up while the berg was part of its mother glacier. Lighter colored streaks may result from layers of airborne dust. Antarctic explorer, Sir Ernest Shackleton, testified about icebergs before the British Board of Trade:
"There are many bergs I have seen that appear to be black, due to the construction of the berg itself. Again...if it is not of close construction it is more porous and taking up the water does not reflect light in any way."
Ernest Shackleton
David G. Brown, Parks E. Stephenson
May, 2001
Presented for consideration by the Marine Forensic Panel (SD-7) chartered by the The Society of Naval Architects and Marine Engineers at Gibbs & Cox, Inc., Suite 700, 1235 Jefferson Davis Highway, Arlington, Virginia on Thursday, May 31, 2001
Comment and discuss