Cumulative factors in underwater damage to Titanic


R L W

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Apr 5, 2021
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After having reflected on the wreck, and on all information provided over my lifetime, I am moved to conclusions which heretofore may not have been emphasized collectively, albeit, individually, they may have been noted. I further must include the irony that, had the ship not been so strongly built, she might not have sunk.

In the short version, based on currents and ship's course, the relative movement of the berg would have been athwart and opposite to ship's course, from an angle 10° to 20° off the port bow. At the time of collision, helm was hard over, and the ship was heeling to starboard. Stem was shifting to port, pivot was heading to object, stern was shifting to starboard. First contact was with the flare of the starboard bow, abaft the anchor, which would have induced a counterclockwise torsion, facing forward, and a flexion to port.

The stiff keel would most have resisted flexion, and the bottom in way of deep floors and doubled plating, but just at the turn from double bottom to single thickness, shear forces would have multiplied. A compounding factor enters play here: on this night, the immersed hull, both outer plates and wetted inner plates, in flooded ballast zones, would have been less elastic than those plates warmed by heated air within the ship. Even a fraction of an inch in expansion differential, under the imposed loads, could have resulted in deformation sufficient to leave mechanically caulked seams opened, once the load was removed. Of course, it is possible that some brittle rivets could have failed, but most of those would have been inside the peak tank or double bottom, right forward, and the higher likelihood is that narrow caulking gaps, aggregated over several hundred feet, could have allowed sufficient flooding to endanger the ship. It is not inconceivable that the stretching of starboard plates and compression of port plates, may have induced lesser leakage to port.

The key component in taking the ship down involved the same factors, further aft: as the ship's bow flexed to port, the after section was still driven by momentum, leading to a stretching of the starboard side, laying in a strain that suddenly was disrupted in way of the engine room, where the bed plate webs further dissipated the load, spread among outer plates, inner bottom, and bed plates. But here, elastic differential was greater. Where forward, the inner bottom was in the 30's, and the hold likely was in the 60's, in the engine room, temperatures would have been above 120°, and when we contrast the steel's elasticity there, as well as the dispersion of load at the sudden increase in load-bearing surface, we get a drastic concentration in the outer plates, just forward of the engines, and a second one aft of the engine beds. Rupture of these seams caused the loss of bottom plates shown in the debris field.

Absent this section, the stiffness was reduced so, instead of extra leverage against forward flooding, this allowed the pivot point to be farther forward, thus increasing the speed of depth increase forward and, by extension, the rate of influx as the multiple of the depth. This, joined with the inner plate damage and flooding, may have cost 30 minutes or more in time afloat. Had the pumps only had to contend with overflow into compartment 5, it is possible the ship could have lived another hour, the sea being calm. But with bottom being breached right aft, there was no way to save the ship.
 
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Jim Currie

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When a ship hits something with her shoulder, that something exerts a force at the point of contact. At that moment, the point of contact becomes a fulcrum (hinge point). The normal dynamics of a turning ship are put on hold until she breaks loose from the "Furlcrum". Think of what happens to a ship moving along a quay wall when the bow accidentally contacts the wall...even for a brief moment.
 

Jim Currie

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There likely was, considering the fact that during the later stages of the sinking, water came up from the floor plates in Boiler Room No 4.
Titanic had a cellular double bottom in the area you are talking about. If the plans are correct, then the inner and outer bottoms were about 3 feet apart extending from side to side and reinforced every three feet of length by "deep floors, i.e. transverse vertical frames three feet high.
WT Bilges, 6 feet deep protected the outer ends of the double bottom tank spaces thus formed.
For seawater to have penetrated upward from the bottom into the deep space above the tank tops i.e. under the floor plates in the boiler rooms, it had to get there through breaches in the outer and inner bottom plating. or pass through the ship's side into the bilges and through the tank side margin plates. The amount of force requires to do such a thing would have been like a grounding on a rock and not one single person would have slept through it. So I think you can forget that idea.
 

Kiku

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Titanic had a cellular double bottom in the area you are talking about. If the plans are correct, then the inner and outer bottoms were about 3 feet apart extending from side to side and reinforced every three feet of length by "deep floors, i.e. transverse vertical frames three feet high.
WT Bilges, 6 feet deep protected the outer ends of the double bottom tank spaces thus formed.
For seawater to have penetrated upward from the bottom into the deep space above the tank tops i.e. under the floor plates in the boiler rooms, it had to get there through breaches in the outer and inner bottom plating. or pass through the ship's side into the bilges and through the tank side margin plates. The amount of force requires to do such a thing would have been like a grounding on a rock and not one single person would have slept through it. So I think you can forget that idea.
In his famous book, A Night to Remember, Walter Lord testifies to this event. What other likely causes could have caused the water to come up from the plates?
 

Jim Currie

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In his famous book, A Night to Remember, Walter Lord testifies to this event. What other likely causes could have caused the water to come up from the plates?
The coal bunkers were below the boiler room deck plates. One of the biggest dangers in a stowage of coal is spontaneous combustion. This can only happen with "wet" coal.
Believe it or not, a ship's side "sweats" on the inside... moisture-laden warm air in the boiler rooms and holds condenses against the cold side shell plating. The water produced has to go somewhere or be regurarly pumped out. In the case of the coal bunkers, I suspect there were drain holes at the bases of the non WT transverse bulkheads. If water gained access to any of the bunkers, it would pass through the drain holes and first fill the space below the boilers, then eventually rise above the floor plates. Just a guess.
 
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Kiku

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The coal bunkers were below the boiler room deck plates. One of the biggest dangers in a stowage of coal is spontaneous combustion. This can only happen with "wet" coal.
Believe it or not, a ship's side "sweats" on the inside... moisture-laden warm air in the boiler rooms and holds condenses against the cold side shell plating. The water produced has to go somewhere or be regurarly pumped out. In the case of the coal bunkers, I suspect there were drain holes at the bases of the non WT transverse bulkheads. If water gained access to any of the bunkers, it would pass through the drain holes and first fill the space below the boilers, then eventually rise above the floor plates. Just
The coal bunkers were below the boiler room deck plates. One of the biggest dangers in a stowage of coal is spontaneous combustion. This can only happen with "wet" coal.
Believe it or not, a ship's side "sweats" on the inside... moisture-laden warm air in the boiler rooms and holds condenses against the cold side shell plating. The water produced has to go somewhere or be regurarly pumped out. In the case of the coal bunkers, I suspect there were drain holes at the bases of the non WT transverse bulkheads. If water gained access to any of the bunkers, it would pass through the drain holes and first fill the space below the boilers, then eventually rise above the floor plates. Just a guess.
Thanks for your answer!
 

R L W

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Apr 5, 2021
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There also is speculation that there was damage on the underside of the ship on the double bottom.
Quite so! That is precisely what I covered in the second to last paragraph: elastic differentials led to the athwartship tear that rent and dislodged the large segment of outer bottom plating.
 

R L W

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Apr 5, 2021
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My second to last paragraph covered that issue: the elastic differential in the heated engine room bed plates, versus that of the outer hull plates, was substantial. Whereas the innermost plates already were more expanded, with a consequent strain on the outer, the surge of forces through the "hull girder" would have tended to focus on the area with the least flexibility, the riveted thwartship seam in the outer plates, at the very forward end of the engine room.
History shows that grounding, collision with a massive object, or impact with an enormous hydraulic force, will transfer force through the hull to the weakest point, in this case, the inelastic, stress concentration point forward of the engine bed double floors and triple plating. It is similar to the trying to tear a meat sandwich: the bread tears while the meat stretches. Here, the warm inner plate could flex, where the freezing outer plate tended more to brittleness than flexion.
 

R L W

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Apr 5, 2021
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In oil fired ships, double bottoms were used for bunkerage and ballast, but in coal fueled ships, bunkers were always behind bulkheads, watertight or non-watertight, as coal had to be shoveled out, not feasible other than in gravity fed stowage. The holes you see in the plan elevations, are lightening holes and access holes, for inspection, painting, and mainly, for free pump communication, in case they be needed for seawater ballast.
 

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