Titanic and the Iceberg

By Roy Mengot

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It's been popular lore in the Titanic story that the iceberg was spotted 37 seconds before impact and the ship was too large and under ruddered to avoid it. This may not have been the actual fact on the night of April 14, 1912. A willingness to believe Titanic couldn't turn quickly may have served Harland & Wolff and the White Star Line to hide the fact that the berg simply wasn't seen until Titanic was nearly on top of it.

A key definition in understanding the testimony is the nautical term 'point'. To describe where an object is relative to the ship, 90 degrees is divided into eighths. "4 points off the port bow" is 45 degrees left of the direction of travel. Two points is 22.5 degrees but people can picture half of a 45 degree angle easier than they can work with compass degrees.

The origin of the 37 second figure came when Edward Wilding of Harland & Wolff and a designer of the Olympic class ships testified on day 27 before the British inquiry:

25292. Does that complete the information? - No, there is a little more information that I think the Court wishes to have. Since the accident, we have tried the "Olympic" to see how long it took her to turn two points, which was referred to in some of the early evidence. She was running at about 74 revolutions, that corresponds to about 21 1/2 knots, and from the time the order was given to put the helm hard over till the vessel had turned two points was 37 seconds.

25293. (The Commissioner.) How far would she travel in that time? - The distance run by log was given to me as two-tenths of a knot, but I think it would be slightly more than that - about 1,200 or 1,300 feet.

Given the speed, Wilding's numbers for the distance covered, with some addition drag caused by the turn, are correct. However, the 37 second time for Olympic is not consistent with the numbers for Titanic's trials in the high speed turn. In fact, 37 seconds for 2 points is almost 50% greater than what Titanic achieved in her trials off Belfast Lough. His calculation of 12-1300 feet has also reenforced the belief that the berg was spotted at a distance of a quarter mile (400 meters).

The 2 points of turn is significant because it helps to determine how far away the fatal iceberg was when it was first sighted. Quartermaster Hitchens was at the wheel of Titanic during the collision, and while there were inconsistencies in his testimony, he remained consistent on the ship achieving 2 points of turn before the collision started. Fred Fleet in the crow's nest also thought the ship had one or two points of turn in his testimony. Of the survivors in a position to observe the events, these two men are the only ones to comment on the turn.

Plotting Titanic's trials sheds some light on the maneuverability of the ship. In a standard maneuver, Titanic was cruising at nearly full speed, 21.5 knots, and upon passing a marked point, went into a full hard turn and the turning radius was measured. The results showed a 3850' diameter circle (1174 meters). The forward movement of the ship was 2100 feet (640 meters) or about 10% more than the radius of the circle. This was due to the slightly sluggish start as the rudder was turned and began to dig in to throw the stern outward as the ship worked into a full turn.

Figure 1 shows the turning radius of the circle and includes the 10% extended curvature on the forward side of the circle, although it is barely perceptible. A circle with a diameter of 3850 feet has a circumference of 12,100 feet (3688 meters) and traveling at 21.5 knots or 35.5 feet (10.8 meters) per second, Titanic traversed the circle in 5.6 minutes (340 seconds). On average, 360 degrees in 340 seconds is just under 1 degree per second.
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Figure 1 - Turning 2 points to the collision point

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Plotting the tuning radius out in scale reveals a few interesting things:

1) The berg as drawn is roughly 660 feet (200 meters) in diameter. Since it is not known how large the berg actually was, it doesn't matter how large we draw it. For an iceberg approaching the sizes described in testimony, Titanic was left of its center, hence Murdoch ordered a left turn around it.

2) Getting two points of turn on the ship can be achieved in about 25-30 seconds (conservative estimate) by the data from the trials.

3) It takes 25 seconds to pass the full length of the ship past a given point at 21.5 knots.

4) At full turn, the rudder post is about 75 feet (23 meters) outside the circle made by the tip of the bow.

Of particular interest from the testimony was Hitchens' statement that he turned the ship to port and scarcely had the helm over when the collision began. After follow-up questions, he admitted the helm was full over when the collision started. He further stated that he had 'two points' of turn. Frederick fleet testified the ship was already turning while he was on the phone to the bridge, indicating that the bridge had seen it at about the same time and was already in action.

How fast could Titanic turn its rudder? The steam powered steering gear atop the rudder under the poop deck consisted of a primary and back-up steam engine controlled from the helm on the bridge or docking bridge. The steam engine turned gears that could turn the rudder 60 degrees off center in the desired direction. From evidence to follow, Titanic appears to have been able to get the rudder full over from center in 5-7 seconds.
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Figure 2 - The steam driven steering gear of the Olympic class ships

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The Porting maneuver

With the stern swinging out so wide during a turn on such a long ship, a maneuver had to be executed to keep the ship from grinding into the berg over it's hole length. In the Titanic scenario this is called 'porting' the ice berg. To turn left to avoid the berg, 1st officer Murdoch gave the order 'Hard a starboard', which meant to starboard the helm as in an old fashioned tiller, which was turned opposite the direction you wanted to go. To swing the stern left and turn the ship to the right, a 'hard a port' order would be given. Thus 'porting' the stern means giving the command to turn the tiller to port (which turns the ship right).

Figure 3 indicates how this maneuver would appear. The blue line is the turning radius of the ship and the red line indicates the path of the rudder post at the stern if the 'hard a port' command were given the instant contact with the berg began. Compare the path of the rudder to Figure 1 if no porting maneuver was attempted.
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Figure 3 - 'Porting the ship' around the iceberg

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When asked at the British hearings, Quartermaster Hitchens denied there was a command to turn to starboard. It's not clear if Hitchens thought they were asking if the ship initially turned right or if they asked about a subsequent porting maneuver. He volunteered no information and may have been coached to only answer the question put to him and say nothing else. Quartermaster Olliver stated at the US hearings that the ship was executing a porting maneuver when he entered the bridge just after the collision and he went outside and saw the ship swinging away from the berg. Seaman Scarrott at the British hearings also testified he saw the stern swinging away before the stern had cleared the iceberg.

What does this say about the maneuverability of the ship? As mentioned, it takes 25 seconds for the ship to pass a given point. If Titanic's helm was hard over in the turn to port, then in the next 15 or so seconds after the start of the collision, the helm was thrown all the way over in the opposite direction and the rudder responded. This indicates that the rudder could be turned hard over from center in 5-7 seconds. Bringing the rudder back to center will stop the turn more quickly as the water flow aids in straightening the ship. Getting even part of a turn in the last 7-10 seconds before the berg went astern of the ship would suffice in clearing the stern.

The following photo was taken by Father Browne during the run to Queenstown. The ship performed some lazy-S turns to swing the compasses. As can be seen by the wake, Titanic appears to be turning nicely.
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Figure 4 - Titanic performing turns between Cherbourg and Queenstown

The retarded turn to port upon sighting the ice is not consistent with the responsiveness of the ship in the subsequent turn to starboard.

Effectiveness of lookouts

On a dark moonless night, the main way to spot an iceberg is by water breaking around the base. This was not possible for Titanic due to the extraordinarily calm weather. While ice bergs generally appear white, frost diffuses light. If little light is reaching the berg, then even less is reflect back to the viewer.

One of the ways objects are spotted from a ship is if the form partially blots out the sky or distorts the horizon. Eye level from Titanic's crow's nest was about 24 feet (7.3 meters) higher than the bridge. While this extends the line of sight to the horizon by a few miles, it had the side effect that objects on the water will be below the horizon out to a greater distance as well. A 70' (21 meter) iceberg will be below the horizon from the crows nest for about 3 miles (5 km) from the ship. From testimony, it appears that Murdoch on the bridge saw the berg about the same time the lookouts reported it. Fred Fleet testified that the ship was already turning while he was on the phone to report it.

Captain Lord on the Californian testified that he had little experience with ice and all the reports placed ice along his more northerly route to Boston. Despite his admitted ignorance of ice, he placed two additional lookouts; one on the mast above the crow's nest and another of the prow of the ship, lower than the crows nest. As a testament to the darkness, Californian had to turn sharply to avoid icebergs, even though they were going a little more than half Titanic's speed and had the extra eyes looking for them. He subsequently decided to stop for the night.

Engine effects

4th officer Boxhall testified that he thought the engines had been reversed when he arrived on the bridge moments after the collision. All of the testimony from several crewmen down in the engine spaces indicate a stop order was received, but the engines were not stopped or reversed before the collision began. This indicates that the rudder was receiving the full benefit of water flowing past from the ship's speed and the action of the center propeller.

It has been discussed that reversing the engines would have the effect of reducing rudder effectiveness by interrupting the flow of water passing the rudder and removing the force of water coming off the center prop. While it's not stated as a condition in Wilding's testimony about the 37 seconds, if the turning exercise with Olympic also involved reversing the engines as per Boxhall's scenario, then the discrepancy between Titanic's turning performance at the trials and Olympic's performance can be explained. The initial loss of speed from reversing the engines on Olympic would be minimal, as Titanic's trials also indicated it would take over three minutes to stop the ship from full speed.

It has also been discussed that reversing one engine would aid in turning the ship. While this is true, it doesn't become an issue in the Titanic scenario. Murdoch knew he needed to turn and then swing back the opposite way to clear the stern. Reversing one engine to help the turn to port would then hamper the swing back to starboard. Avoiding the obstacle requires two turns. In any event, time was too short for a complicated maneuver such as tampering with the engines. Even the order to stop could not be carried out in time.

Conclusions

37 seconds does not fit the profile of Titanic's turning radius at the trials. A two point turn could be accomplished in something nearer 25 seconds, assuming the ship achieved a full two points of turn. This translates to spotting the ice berg at 900 feet (250 meters) or less rather that 12-1300 feet (400 meters). Actions on the timeline for the collision, such as Fleet phoning the bridge, may have been done in parallel with turning the ship, shortening the timeline. Ultimately, this indicates that the lookouts and Murdoch could not see the berg until they were almost on top of it. At the hearings, the White Star Line and surviving crew were perfectly happy with all the speculation that the ship was under ruddered and unmaneuverable. This speculation, that continues to this day, just hides the fact that the crew just flat couldn't see even large objects and the margin for safety at their speed wasn't there under the conditions of that night. Despite the clear conditions, a reduction in speed was warranted due to the extraordinary darkness.