Questions Than Answers, Part 2
Over the next few weeks I would present my series of CG renderings to Jim and Ken, and they would suggest revisions that I would then use to generate a new set of images. Our give-and-take conversation is too lengthy to reproduce here, but the result of our deliberations is shown in the following series of images.
Titanic at the time of impact, with zero degrees of trim angle.
As reported by eyewitnesses, Titanic would initially heel to starboard, then assume a slight but gradually increasing port list. For the first two hours after the collision, Titanic settled by the bow due to steady and progressive flooding.
At about 2 a.m., the stemhead submerged and water began to work its way up the foredeck. Water also poured into the well deck and found its way into non-watertight openings such as the cargo hatches. The port list became especially noticeable after water found its way into Scotland Road, the working alleyway on E Deck that ran halfway down the port side of the ship.
Water reached the forward end of Boat Deck at around 2:15 a.m. Because of a combination of the ship settling and the trim angle increasing, the propellers started to rise above the surface of the water. Second Officer Lightoller looked down at Collapsible B from atop the port side of the Officers' Quarters and saw that rising water precluded the launch of that boat, so he crossed over to the starboard side where First Officer Murdoch was working the falls to launch Collapsible A. The port list was making this task difficult.
Approximately a minute or two later, Lightoller was standing atop the Officers' Quarters forward of the No. 1 funnel, starboard side, when the ship seemed to, as he would describe later, "take a bit of a dive." Lightoller stated that it felt as if a watertight bulkhead somewhere down below had suddenly given way, but Jim believes that the motion that Lightoller felt was most likely caused by downflooding of the Grand Staircase or another major vertical void. It's obvious at this point that Titanic was transitioning from a state of neutral to unstable equilibrium, and the subsequent sequence of events would happen in rapid succession. In addition to a loss of longitudinal stability, the hull experienced a larger angle of port list.
When the base of the forward funnel was submerged by about 20 feet, it is likely that differential pressure buckled the thin steel of the funnel uptakes, causing the funnel to collapse (due to time and scope restrictions, the positions of the funnels in these CG renders are merely placeholders and do not reflect the actual movement of the funnels after collapse).
Because of the relatively shallow down angle of trim, even the slight loss of buoyancy felt by Lightoller and subsequent settling of the hull caused the water to appear to rush aft along Boat Deck in the manner of, as Archibald Gracie would put it, "a wave on the seashore," washing a multitude of people (Cook John Collins would describe the number to be in the hundreds) from the deck at least as far aft as the Grand Staircase.
Near the No. 2 funnel, Jack Thayer watched as Milton Long attempted to abandon ship by sliding down the starboard side of the hull. Thayer would never again see his friend, but the very fact that Long acted on the notion suggests a significant amount of port list at that point.
This was the moment of maximum stress on the hull. The extreme height of the stern was reported by a number of eyewitnesses...as stated above, I initially chose a 30° angle as a rough average of their accounts and our analysis to date seemed to support this assumption. The shifting centre of buoyancy, though, which appeared to move farther aft and upward than has been previously assumed, prompted me to settle the ship model deeper in the water. This left only the after third of the ship unsupported by water. Assuming (in lieu of a proper flooding survey) that the forward third of the hull was acting under almost complete negative buoyancy, most of the remaining buoyancy in the bow section would therefore be located high in the structure and roughly aft of the Grand Staircase.
It is this assumption that most differentiates our traditionalist break-up scenario from Roger's. In our analysis, the stem arched downward at an increasing rate throughout the course of the sinking. Because the hull was rotating around the centre of buoyancy, the stern rose at the same angle and rate as the bow dropped. Because the rising stern was unsupported by water, though, gravity acted upon it, placing additional loads upon the structure. The port list transferred stresses asymmetrically to the starboard side, where we speculate that they concentrated in the plating directly underneath the sharp angle formed by the aft expansion joint.
The base of the No. 2 funnel collapsed similar to that of the No. 1 funnel, except that it apparently kicked to starboard, impacting Boat Deck just outside the Gymnasium. Restricted by the stays, the top of the funnel would have collapsed almost straight down.