Why did Titanic sink faster when her Boat Deck began to flood?


Cam Houseman

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Why did she? I don't really get it, unless I'm missing something. I mean, it was reported Titanic began to sink faster, but she sank super fast after the Bridge began to flood. Why is that?
 

William Oakes

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Weight of the flooding and gravity.
At some point the weight of the seawater overcame the ballast and away she went.
 
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B-rad

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There was more area for which water could enter the ship. Originally water could only enter through the damage done by the iceberg. Flooding would be rapid but then slow down as the water level inside the ship met the water level outside the ship. Of course if the damage had been limited this equalization would have allowed Titanic to remain afloat. As the ship sank any open portholes or doors would have allowed more water in, but of course to a limited amount. Flooding would continue until the frwd. well deck began to flood, this would allow a massive amount of water to enter the ship through the holds increasing the rate of flooding and weight of the ship. As the ship sank deeper and the upper decks flooded water was no longer limited to the few holes punched by the iceberg, or a few open portholes, but now had free range (so to speak) to enter the ship from all angles.
 
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Cam Houseman

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There was more area for which water could enter the ship. Originally water could only enter through the damage done by the iceberg. Flooding would be rapid but then slow down as the water level inside the ship met the water level outside the ship. Of course if the damage had been limited this equalization would have allowed Titanic to remain afloat. As the ship sank any open portholes or doors would have allowed more water in, but of course to a limited amount. Flooding would continue until the frwd. well deck began to flood, this would allow a massive amount of water to enter the ship through the holds increasing the rate of flooding and weight of the ship. As the ship sank deeper and the upper decks flooded water was no longer limited to the few holes punched by the iceberg, or a few open portholes, but now had free range (so to speak) to enter the ship from all angles.
Ohhhh, thank you! This explains it perfectly
 

Arun Vajpey

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Cam, this is very superbly explained in Sam Halpern's book Report into the Loss of the SS Titanic: A Centennial Appraisal. You should really read it; the relevant bits are in pp 115 to 118.

Yes, the progressive flooding of the bow that resulted in pushing it further and further down was the starting point. When the bow actually went under, that part of the ship lost its buoyancy and as the sinking progressed, the weight of the water above the submerged bow accelerated the process. With the stern now rising out of the water, it was as if the ship was on a pivot; at around 02:15 am this resulted in sudden loss of longitudinal stability and Sam believes that this was the reason for the sudden 'forward lurch' described by many survivors followed by the 'wave' that worked its way towards the stern. The 'wave' was due to sudden displacement of a large volume of water.
 
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Cam Houseman

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Cam, this is very superbly explained in Sam Halpern's book Report into the Loss of the SS Titanic: A Centennial Appraisal. You should really read it; the relevant bits are in pp 115 to 118.

Yes, the progressive flooding of the bow that resulted in pushing it further and further down was the starting point. When the bow actually went under, that part of the ship lost its buoyancy and as the sinking progressed, the weight of the water above the submerged bow accelerated the process. With the stern now rising out of the water, it was as if the ship was on a pivot; at around 02:15 am this resulted in sudden loss of longitudinal stability and Sam believes that this was the reason for the sudden 'forward lurch' described by many survivors followed by the 'wave' that worked its way towards the stern. The 'wave' was due to sudden displacement of a large volume of water.
Thanks Arun. This also explains it very well! :)
Basically, Titanic's interiors slowed the flooding?

I plan to get Sam's book, yes
 

Arun Vajpey

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Basically, Titanic's interiors slowed the flooding?

Well, I guess that's one way of looking at it. Water, like all fluids under the influence of gravity, finds its own level and so when there was uneven flooding at first through the gaps caused by the collision, the intervening structures and bulkheads would have slowed that process. But once they were breached either by overtopping or structural failure, the flooding water in a particular space would have started to equilibrate with those around it and that would obviously continue and hasten the flooding process.

The way I look at it is that the flooding was simply following laws of physics. The terms 'slow' or 'fast' are relative and meaningful only to the human beings caught-up in the process.
 
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As time went on there was less area left to fill. And as B-rad said more area open to the sea for water to come in. Less spaces + more water inflow = accelerated sinking.
 
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Jim Currie

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Since the water entered at a point about 24 feet below the surface, it did so at a pressure of 10.6 p.s.i. If it entered an empty, sealed compartment, it would gave simply pressurized the air in that compartment. However, it did not do so. It entered ventilated compartments thus pushing the air out of these compartments at ever-increasing pressure as the ship sunk deeper. Water would have found it difficult, if not impossible to enter a small hull opening such as a porthole or vent pipe at sea level because it was trying to enter at a pressure of 0.4 p.s.i against air coming out at an ever increasing pressure as the hull sunk deeper. Keep in mind the billowing hatch covers.
Holds and bunkers which were full would not add much to the volume of lost buoyancy. I understand Holds 1 and 2 were full of cargo. Nor would tanks full of liquid.
Although Titanic was tilting by the head, other things were happening: she was losing buoyancy, sinking bodily deeper and acting around a point in he water plane area which was also moving because the water plane areas was getting less and less as more and more of her hull left the water i.e the force of gravity was acting more and more toward the direction of the bow instead of as it was originally, toward the keel almost amidship. She would not have lurched by the head until there had been a sudden inundation. I suggest to you there were two possibilities
(1) When the water level over topped the WT bulkheads or
(2) When the hull girder started to fail and allowed water to enter from aft at the forward end of the engine room i.e. at the moment when the hull started to separate. This would cause a sudden inundation into all the compartment from Boiler room 1, increasing progressively upward, deck by deck as the added water cause the bow and forward end to suddenly sink deeper and hinge down ward.
 
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Cam Houseman

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Since the water entered at a point about 24 feet below the surface, it did so at a pressure of 10.6 p.s.i. If it entered an empty, sealed compartment, it would gave simply pressurized the air in that compartment. However, it did not do so. It entered ventilated compartments thus pushing the air out of these compartments at ever-increasing pressure as the ship sunk deeper. Water would have found it difficult, if not impossible to enter a small hull opening such as a porthole or vent pipe at sea level because it was trying to enter at a pressure of 0.4 p.s.i against air coming out at an ever increasing pressure as the hull sunk deeper. Keep in mind the billowing hatch covers.
Holds and bunkers which were full would not add much to the volume of lost buoyancy. I understand Holds 1 and 2 were full of cargo. Nor would tanks full of liquid.
Although Titanic was tilting by the head, other things were happening: she was losing buoyancy, sinking bodily deeper and acting around a point in he water plane area which was also moving because the water plane areas was getting less and less as more and more of her hull left the water i.e the force of gravity was acting more and more toward the direction of the bow instead of as it was originally, toward the keel almost amidship. She would not have lurched by the head until there had been a sudden inundation. I suggest to you there were two possibilities
(1) When the water level over topped the WT bulkheads or
(2) When the hull girder started to fail and allowed water to enter from aft at the forward end of the engine room i.e. at the moment when the hull started to separate. This would cause a sudden inundation into all the compartment from Boiler room 1, increasing progressively upward, deck by deck as the added water cause the bow and forward end to suddenly sink deeper and hinge down ward.
Thank you for this all encompassing answer, Jim. It makes sense that the flooding slowed due to objects in that corridor or space.

So, what about Scotland Road? Or rooms like the Dining Saloon and Reception Room? Did that hinder the crew's hope of compartmentalization? (as in, Titanic would stop flooding, and sit there)
 

Jim Currie

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Thank you for this all encompassing answer, Jim. It makes sense that the flooding slowed due to objects in that corridor or space.

So, what about Scotland Road? Or rooms like the Dining Saloon and Reception Room? Did that hinder the crew's hope of compartmentalization? (as in, Titanic would stop flooding, and sit there)
As you know, water does not flow up hill Cam. "Scotland (Scotty) Road" was a fore and aft, port side alleyway. It was closed off at the aft end by a manually operated with WT door . For a graphic description of the time you are inquiring about, I suggest you read the evidence of Chief Baker Charles Joughin Day 6 UK Inquiry - particularly from Q6040 onward.
 
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Arun Vajpey

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However, it did not do so. It entered ventilated compartments thus pushing the air out of these compartments at ever-increasing pressure as the ship sunk deeper.
Surprisingly, I have found that many 'ordinary' people who have asked me questions about the Titanic in pubs, parties and such have failed to consider something very obvious. This is that when intact, on a ship like the Titanic, the thing that took up most space in terms of volume was air. Thus, when a room like a half-empty cargo hold flooded, the water displaced that air and took up its space, thus making a huge difference in weight and affecting buoyancy.
 
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Cam Houseman

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As you know, water does not flow up hill Cam. "Scotland (Scotty) Road" was a fore and aft, port side alleyway. It was closed off at the aft end by a manually operated with WT door . For a graphic description of the time you are inquiring about, I suggest you read the evidence of Chief Baker Charles Joughin Day 6 UK Inquiry - particularly from Q6040 onward.
yes, forgot Joughin and Mr. Wheat, and how they sealed the Horizontal Sliding WTDs. I really meant the forward end of Scotland Rd, sorry for not making that clear. Wouldn't that worsen/begin the Port List, and increase the flooding rate?
 

Jim Currie

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yes, forgot Joughin and Mr. Wheat, and how they sealed the Horizontal Sliding WTDs. I really meant the forward end of Scotland Rd, sorry for not making that clear. Wouldn't that worsen/begin the Port List, and increase the flooding rate?
The flooding rate would not increase until the sea over-topped an empty compartment or until the hull breach was widened or increased at sea level.
As for the port list -think deeply about that ;)
 
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Arun Vajpey

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As for the port list -think deeply about that
Jim, instead of speaking in riddles, do you mind explaining that comment? I always assumed that the port list occurred because there were more open spaces on the port side of the ship, including 'Scotland Road'. I was under the impression that as flooding water started equilibrating in various spaces, it filled the portside ones as well and the increased weight of the water on that side of the ship therefore contributed to the eventual port list.

Even though 'Scotland Road' had a manually operated WTD at its aft end, the space must have flooded at some stage during the sinking?
 
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The flooding rate would not increase until the sea over-topped an empty compartment or until the hull breach was widened or increased at sea level.
True, and in fact the flooding rate would start to actually decrease initially as the flood water inside a compartment started rise for a hull breath near the bottom of a compartment such as the case with Titanic.
 
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Jim Currie

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.......in fact the flooding rate would start to actually decrease initially as the flood water inside a compartment started rise for a hull breath near the bottom of a compartment such as the case with Titanic.

It is the across-hull flow which concerns me and should do others, Sam.

When a ship is bilged in flat calm conditions, she will adopt a list to the side she is bilged on and retain that inital list as she sinks bodily. She may, in fact, roll over on the side of the list if the amount of flooding causes the main deck edge to submerge. The water level does not equalize across the beam width as a natural process.
However, if water is pumped from the low side,at the same rate or faster than the rate of downflooding as, for instance, from an undamaged DB., then, if the rate of pumping-out exceeds the flooding rate she will regain buoyancy and start to come upright again. As this happened, the positions of B and G change and the metacentric height reduces.
In the case of Titanic, an already "tender" vessel became even more tender and the potential for free surface effect increased. When she was upright, then and only then did the water flooding-in start to flow across the hull. Chief Officer Wilde was very much aware of this. As I said to Cam.. it doesn't flow uphill.
As I have written: I suspect they intitially thought that the ship's bottom was holed and the ballast tanks breached. If there was ballast in those tanks and they were not holed, that would have caused the ship to come upright at first without having any effect on the rate of the downflooding. Thus equalize the water level and bring her totally up right, but then, (possibly due to a modicum of free surface effect. ) she lolled to port, steadied and eventually took an on ever-increasing port list. as she went down by the head and stabalized. In fact, if I am right, the pumping out action caused anormous complication of heel and trim during the sinking process. Cam is right in that there were more fee volume to fill on the port side than on the starboard side one free cross flow was established.
 
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