Reducing speed in ice

[Mark Baber]

In 1894, Henry Parsell, commander of White Star's then-flagship Majestic I, testified before a joint Board of Trade/Admiralty committee on floating derelicts. In a brief diversion from derelicts, the following exchange took place:

666. Have you ever struck ice when your vessels crossed?---No. I have never struck ice.

667. Have you ever found yourself in the neighbourhood of ice?---I have been in a field of ice as much as six or eight hours together, and I have seen icebergs, a great number of icebergs.

668. Do you slow down?---Yes, we invariably, in the ice region before dark, slow the ship down.

Source: Report of a Joint Committee of the Admiralty and the Board of Trade ... on the subject of Floating Derelicts. (1894),https://books.google.com/books?id=uxREAQAAMAAJ&pg=PA117&lpg=PA117&#v=snippet&q=joint committee&f=false

 

[Doug Criner]

About 10+ years ago, we sailed in a small cruise ship during July on the northwest of Svalbard, far above the Arctic Circle. We went as far north as the continuous pack ice. Traveling back south in daylight, we encountered floating ice, mostly growlers, but some larger. No huge bergs. The ship slowed down and maneuvered to avoid the floating ice. We left the ice field before darkness.

 

[Adam Went]

It's just common sense really, regardless of what type of transport you're using, to adjust your speed according to the conditions. Unfortunately in the case of the Titanic I'm not convinced that even if she had been travelling at a significantly slower speed that the impact with the iceberg would have been avoided - it may have altered it to some degree, but spotting the hazard and then having the manoeuvrability to avoid it in time remains the issue with such a huge ship.

Cheers,
Adam.

 

[David G. Brown]

It’s widely accepted that circumstances alter cases. Safe speed for a ship operating in a channel that is relatively narrow and filled with ice is much slower than safe speed on the open ocean. Even though Titanic was approaching a known field of ice, even at the time of the accident it was not surrounded by bergs, bergy bits, or growlers. It was certainly not in a narrow channel nor constrained in its maneuvers by shallow water. Slowing its speed was not required by prudence because it was not the safest action to take. It would have been better by far to have taken the ship far south of the known ice before taking a rhumb line course to New York.

Assuming the intention was to make the fastest passage possible on Titanic’s maiden voyage, slowing or stopping was out of the questions. By stopping the ship would have lost all ability to maneuver to avoid collision with other vessels operating in the area. And, it would have been seven hours late to New York. Slowing to half speed would have cut the delay in half, but the ship would still have been steaming through a dangerous ice field at night. Neither slowing or stopping would have been prudent under the prevailing conditions.

But, altering course is another matter. Not only would it have added less than an hour to the duration of the voyage, it would also have kept the ship clear of most or all dangerous ice that night. Titanic was following the published westbound steamer route. As required, the ship altered from its great circle route to a rhumb line to New York at 42 N 47 W, a spot known as “The Corner.” This course change came at 7:45 pm in April 14th time.
The distance from “The Corner” to Sandy Hook at the entrance to New York harbor as shown in period nautical texts was 1,240 nautical miles on a rhumb line of 266 deg. That track would have crossed the 50W meridian at about 42 52N and forced Titanic to steam through the ice field at night.

However, had the ship continued farther south on its great circle route there would have been no iceberg in its path and, presumably, no disaster. The few extra miles would not have resulted in any significant delay in reaching New York. If Captain Smith instead took his ship from “The Corner” to 41 N x 50 W, Titanic would have been in much safer water. This departure from the published steamer track was allowed for safety. It would have added roughly 18 nautical miles to the voyage to Sandy Hook. At the 22 knots Boxhall used in his calculations, those extra miles would have added about 49 minutes of steaming to the passage – less than an hour.

So, slowing to half speed would still have exposed Titanic to ice danger by forcing it to pick through an ice field in the dark. Stopping meant exposing the ship to collision with another vessel because Titanic could not have maneuvered as required by the Rules of the Road. Either option would have added up to seven hours additional time to the voyage. The safest action – steaming well to the south before taking the rumb line to Sandy Hook – would have cleared most or all of the ice while adding less than an hour to the overall trip.

The question to be asked is not, Why didn’t Titanic slow down?” Rather, the real puzzler is, “Why was Titanic so far north at the time of the accident in the face of known ice conditions?”

-- David G. Brown

 

[Jim Currie]

When discussing this interesting question, it should always be kept in mind that Captain Smith's decisions were based on his very considerable knowledge of the routes in question and the normal behaviour of the sea ice in early April.

Captain Smith had warnings of ice on his track some 135 miles to the west of The Corner. He had written in the Order Book that the ship was to be turned onto her final course for New York at 5-50pm that evening. This meant that he thought Titanic would be in the vicinity of the position where the ice was reported to have been at around midnight...15 hours after the time when it was last seen.
Under normal circumstances.. i.e. a prevailing weather system from the SW and NE trending currents, he probably decided that the ice would be about 30 miles to the north and eastward of his expected position when Titanic crossed the 50th meridian.
The sea temperatures recorded by the SS Californian in the vicinity of The Corner on the same day suggested that the extension of The Gulf Stream was transporting surface water to the north of the 42nd parallel. The sea temperature reading taken on board Titanic when in the same area that Sunday afternoon would have been similar and would have reinforced Smiths estimates of ice movement.
All these assessments would have been made by him during the early afternoon of April 14. Unfortunately. he had no idea that a High Pressure area was building and that the wind would drop away after 6 pm. This would allow Titanic to achieve her optimum speed at for engine revolutions of 75 rpm. My best guess is that she made a knot faster that the speed used by Smith in his calculation and consequently, she was up to the ice area earlier than expected and the ice had stopped moving.
Captain Smiths's main concern was small ice... not icebergs. So far south as that, sea ice is more influenced by wind than by current. Such ice can only be detected in time if the tell-tale breaking waves round its waterline are seen in time. Smith and Lightoller knew this and had taken the normal precautions.

As for reducing speed; The Carpathia was making about 14 knots and the Californian was making 11 knots yet the former, even with much enhanced lookouts, had just enough time to avoid the berg that did for Titanic. The latter did not see the ice in time and actually entered the fringes of the pack before her bow was swung clear.

In my early days, there was a mantra that was dinned into us..."When considering actions to be taken, always have due regard for the circumstances of each case" In my opinion, Smith did nothing more than follow that mantra to the best of his ability.

Jim C.

 

[David G. Brown]

Jim -- You hit the ol' thumb on the nail. Thanks for your analysis.

-- David G. Brown