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Old 04-21-2012, 03:45 PM
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Titanic: Why wasn't the watertight bulkheads extended to the top

According to Wikipedia:

Quote:
Although the watertight bulkheads extended well above the water line, they were not sealed at the top. If too many compartments were flooded, the ship's bow would settle deeper in the water, and water would spill from one compartment to the next in sequence, rather like water spilling across the top of an ice cube tray.
As an amateur, I can't help asking the question: Why on earth were the walls in between the compartments not extended to the roof? Even though they couldn't have foreseen the particular damage Titanic suffered, it just seem so obvious to me that "compartments" whose whole point (as far as I understand it) are to contain water from a leakage should be separated by walls from bottom to top of the deck. What am I missing in my ship building logic?
Old 04-21-2012, 03:56 PM
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Money.
Old 04-21-2012, 04:03 PM
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Getting around on the ship would have been difficult. If you are down on one of the lower levels and you want to go to the back of the ship, you would have to go all the way to the top, then go back, and then go all the way back down again (you can't have hallways going through your watertight bulkheads or they aren't watertight bulkheads any more).

And besides, no one really thought that they would puncture that many of the compartments. Trying to convince them to make the bulkheads go all the way to the top would have come across as silly and paranoid. They didn't think it was a very realistic scenario.
Old 04-21-2012, 04:09 PM
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Because they wanted a grand and impressive staircase and the bulkheads got in the way.
Old 04-21-2012, 04:18 PM
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* sigh *

No, the OP is not asking why the watertight bulkheads did not extend to the top of the Titanic, he is asking why the bulkhead had spaces above them down in the basement--whatever it was called--of the ship.

Last edited by Eve; 04-21-2012 at 04:18 PM.
Old 04-21-2012, 04:28 PM
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Apparently they felt the possibility of the water rising above the level of the bulkhead was too remote to justify the extra expense of building taller bulkheads.
Old 04-21-2012, 04:32 PM
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Quote:
Originally Posted by engineer_comp_geek View Post
Getting around on the ship would have been difficult. If you are down on one of the lower levels and you want to go to the back of the ship, you would have to go all the way to the top, then go back, and then go all the way back down again (you can't have hallways going through your watertight bulkheads or they aren't watertight bulkheads any more).
The bulkheads had watertight doors, so this wasn't the reason.

Quote:
And besides, no one really thought that they would puncture that many of the compartments. Trying to convince them to make the bulkheads go all the way to the top would have come across as silly and paranoid. They didn't think it was a very realistic scenario.
This is the reason. If only a few compartments were punctured, they would fill to the waterline and stop. Since the bulkheads went above the waterline, they were deemed to be sufficent. They would only fail if enough compartments were breached so that enough water got in to force the bow of the ship to sink below the height of the bulkheads. Apparently whomever did the designing didn't consider that likely enough to make it worth the cost of building higher bulkheads.

Note they did build them higher in the bow and stern, presumably because a hit on the bow or stern was considered more likely then a hit on the side.

Quote:
Originally Posted by Eve
No, the OP is not asking why the watertight bulkheads did not extend to the top of the Titanic, he is asking why the bulkhead had spaces above them down in the basement--whatever it was called--of the ship.
I don't read it that way.

Last edited by Simplicio; 04-21-2012 at 04:35 PM.
Old 04-21-2012, 04:58 PM
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Water tight bulkheads are expensive. The higher above the water line they go the more expensive they become. Putting water tight hatches in the bulkheads would add to the expence.
Old 04-21-2012, 05:02 PM
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To clarify what I meant (hopefully), as I understand it, the "bulkhead" walls looked like this:

-------------------------------------------
Deck this and that
-------------------------------------------
Deck this and that
-------------------------------------------

| "Compartment" | "Compartment" |
| "Compartment" | "Compartment" | [water surface?]
| "Compartment" | "Compartment" |
-------------------------------------------
[below ship]

... where the walls didn't go to the "roof" of the lower deck, and allowed the "water spilling across the top of an ice cube tray".

While I would assume the walls should be like this:


-------------------------------------------
Deck this and that
-------------------------------------------
Deck this and that
-------------------------------------------
| "Compartment" | "Compartment" |
| "Compartment" | "Compartment" |
| "Compartment" | "Compartment" | [water surface?]
| "Compartment" | "Compartment" |
-------------------------------------------
[below ship]


... where the walls did reach the top of the deck and would isolate the water in case of leakage somewhere would be contained by the compartments.

(Sorry if being somewhat incomprehensible, English is not my first language and ship engineering terms is not my speciality either.)
Old 04-21-2012, 05:17 PM
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Penny-wise, pound-foolish head slaps kicked in only after Titanic sank.
Quote:
Following the loss of the Titanic and the subsequent inquiries, several design changes were made to the remaining Olympic-class liners. With Britannic, these changes were made before launching. (Olympic was refitted on her return to Harland and Wolff.) The main changes included the introduction of a double hull along the engine and boiler rooms and raising six out of the 15 watertight bulkheads up to 'B' Deck.

Last edited by Kenm; 04-21-2012 at 05:19 PM.
Old 04-21-2012, 05:27 PM
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Here's a picture. The red lines are the bulkheads.

I'm thinking "not sealed" just means they aren't watertight between the bulkhead and ceiling so if there's hydraulic pressure it'll be able to push through the crack if it makes it up to that point.
Old 04-21-2012, 05:46 PM
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Quote:
Originally Posted by Simplicio View Post
pparently whomever did the designing didn't consider that likely enough to make it worth the cost of building higher bulkheads.
Thomas Andrews


I seem to recall as well that some of the bulkhead doors were left open that night, to make passage between easier for the crew.
Old 04-22-2012, 04:59 AM
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Simplicio has it right. Raising the bulkheads wouldn't have made a great deal of difference in the case of Titanic. Water only started to spill over the top of them in the latter stages of the sinking, when the bow was very low in the water. If they'd been higher, the ship would have only stayed afloat for a few minutes longer.

Quote:
Originally Posted by Simplicio View Post
Note they did build them higher in the bow and stern, presumably because a hit on the bow or stern was considered more likely then a hit on the side.
The bow and stern bulkheads are higher because flooding at the ends of the ship changes the angle it sits in the water.
Old 04-22-2012, 05:00 AM
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I think what doomed the Titanic was the failure of its hull plates not the lack of watertight till the decks.
Old 04-22-2012, 05:46 AM
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Wikepedia does say though, that:

Quote:
Unfortunately Andrews was overruled to have 36 more life boats and a double hull and water tight bulkheads that went up to B deck.
So the ship's architect clearly thought it would've been a good idea, just like the OP. Poor Andrews, I always felt so sorry for him.
Old 04-22-2012, 06:13 AM
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Quote:
Originally Posted by Alka Seltzer View Post
Water only started to spill over the top of them in the latter stages of the sinking, when the bow was very low in the water. If they'd been higher, the ship would have only stayed afloat for a few minutes longer.
I might be misremembering this. Looking at the Britannic article, it states that due to the design changes she could stay afloat with the first six compartments flooded, which would have been enough to save Titanic.
Old 04-22-2012, 06:33 AM
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Technically speaking the ship might not sink however as soon the bow slipped below the waterline sealed bulkheads would not prevent rolling over or even flipping upside down.
Old 04-22-2012, 05:53 PM
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Quote:
Originally Posted by AK84 View Post
I think what doomed the Titanic was the failure of its hull plates not the lack of watertight till the decks.
That isn't quite the case as I understand it. There is no evidence I've seen or read of that the hull plates failed. The iceberg impact would have damaged almost any steel-hulled vessel in much the same way, with the possible exception of a naval dreadnaught (battleship) with fully armored and blistered hull sides...and those didn't come along until a bit later.

The problem was that the damage compromised several compartments, leading to their flooding, and the ship's floatation was no longer assured.

The miracle was that she didn't capsize before going under. That fact allowed the lifeboats to at least be launched. Most big ships that flood, do capsize at some point before finally sinking.
Old 04-23-2012, 11:49 AM
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Quote:
Originally Posted by Eve View Post
* sigh *

No, the OP is not asking why the watertight bulkheads did not extend to the top of the Titanic, he is asking why the bulkhead had spaces above them down in the basement--whatever it was called--of the ship.
The Titanic had a basement!?
Old 04-23-2012, 12:00 PM
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Yes, just like the Alamo.
Old 04-23-2012, 12:20 PM
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Not only "extended to the top" but "sealed at the top" would have been much better. As stated above, the water tight compartments were really open topped boxes. Submerge them enough and water would indeed pour from one to another like a giant ice cube tray.

But if they were sealed boxes (or sealable -- water tight bulkheads and doors on the top as well as the sides) then water could enter but would stop when it could no longer displace air. The water level would rise, probably above the level of the leak, but once compression of the air balanced the water pressure, no more water would flood in. Any passengers and/or crew trapped inside would have been able to breathe and survive for a considerable time. Those people could even have congregated at any watertight hatch above the interior water line, opened it briefly to exit en mass, and shut it again. Some water would have entered, but would again have stopped once pressures equalized.

Of course, the costs in inconvenience (to both loading and within-ship movement) as well as capital outlay would not have been trivial. But the ship might actually have been unsinkable.
Old 04-23-2012, 02:06 PM
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Quote:
Originally Posted by Wakinyan View Post
According to Wikipedia:

As an amateur, I can't help asking the question: Why on earth were the walls in between the compartments not extended to the roof? Even though they couldn't have foreseen the particular damage Titanic suffered, it just seem so obvious to me that "compartments" whose whole point (as far as I understand it) are to contain water from a leakage should be separated by walls from bottom to top of the deck. What am I missing in my ship building logic?
If I'm understanding you correctly, you're under the same misconception my father was.

Is what you're asking is why, for example, the E Deck watertight bulkhead didn't extend all the way up to the "roof," which would be the underside of "D" Deck? As if the "wall" (bulkehead) had an actual gap at the top?

Or are you asking why the watertight bulkheads didn't extend all the way up to A deck? Or even the Boat Deck?

CannyDan: the kind of compartmentalization you describe is fairly standard on warships, and it's still no guarantee against sinking. If you build a ship out of steel, and then poke enough holes (or a big enough hole) in it, it will, sooner or later, sink.
Old 04-23-2012, 02:41 PM
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Quote:
Originally Posted by ExTank View Post
Is what you're asking is why, for example, the E Deck watertight bulkhead didn't extend all the way up to the "roof," which would be the underside of "D" Deck? As if the "wall" (bulkehead) had an actual gap at the top?.
Yes, this is what I was asking, where "E" deck would be the lowest (the "compartmens" deck in my illustration above).
Old 04-23-2012, 02:51 PM
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You can get great deals on souvenirs in the Alamo basement. Just ask one of the docents.
Old 04-23-2012, 03:12 PM
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In warships, which can expect to sustain battle damage, there is much greater compartmentalisation and a good deal of effort is devoted to damage control, both in the form of active measures to shore up bulkheads, fight fire and counter flood, and passive ones like phoning the damage control centre for permission to open hatches and confirming that they are dogged down again after you passed through the compartment. Passengers won't stand for being treated like that. They will leave doors open, will think of themselves before the ship, and won't obey orders that might seem a bit dangerous. They're paying for a pleasant sea voyage, not to re-enact Two Years Before the Mast. They will pretty well negate any design features that might save a ship full of disciplined sailors.
Old 04-23-2012, 03:19 PM
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Quote:
Originally Posted by Wakinyan View Post
Yes, this is what I was asking, where "E" deck would be the lowest (the "compartmens" deck in my illustration above).
Then in that case, yes, the bulkheads did extend all the way to the "roof," with the "roof" being the underside of the next deck up.

What they did not do is extend all the way up to A Deck, the last enclosed deck before the Boat Deck, which was a "weather deck;" an open-air, unprotected deck exposed to the weather.
Old 04-23-2012, 04:03 PM
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ExTank, warship compartmentalization is exactly what I had in mind. I admitted that it had costs, even insurmountable costs, in convenience and treasure, as Mk VII points out.

Nit pick regarding a "big hole"- one can in theory remove the entire bottom of a floating hollow steel container (a ship, say, or a simpler shape like a tin can) without it sinking, as long as an air bubble of sufficient buoyancy remains to float the weight of steel. (Capsizing is a whole different issue.) Water inside at or below the water line doesn't constitute "weight" and won't "pull the ship down". Adding another hole, no matter how large or small, that allows the air to escape will indeed inevitably lead to sinking though, as water replaces the air. And fighting ships are certainly subject to multiple holes
Old 04-23-2012, 04:39 PM
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(Using the link in post #11 as a guide.)

It appears that all of the bulkheads go up as far as "E" deck, with the bow and stern areas having bulkheads that go up to "D" deck.

I've always assumed that the bulkhead "F" (between boiler rooms number 4 & 5), for example, does indeed reach the underside of "E" deck, meaning that flooding cannot proceed fore and aft until it gets above "E" deck, and that "E" deck itself was not watertight (meaning there were ladder/stairwells down from "E" deck into boiler room 5 that were not watertight).

To make "E" deck watertight would have added a lot of weight (and cost) high up in the ship, as well as constricting crew, cargo, or passenger traffic.

How do we find similar drawings for modern cruise ships?
Old 04-23-2012, 04:53 PM
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Quote:
Originally Posted by AK84 View Post
I think what doomed the Titanic was the failure of its hull plates not the lack of watertight till the decks.
The steel was of inferior quality -- is that what you're talking about? It became especially brittle in colder water.
Old 04-23-2012, 05:11 PM
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The brittle qualities of steels at freezing (and not so freezing) temperatures were not well understood at this time. The ship was not the only on with this problem.
Old 04-24-2012, 03:53 PM
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Quote:
Originally Posted by ExTank View Post
Then in that case, yes, the bulkheads did extend all the way to the "roof," with the "roof" being the underside of the next deck up.

What they did not do is extend all the way up to A Deck, the last enclosed deck before the Boat Deck, which was a "weather deck;" an open-air, unprotected deck exposed to the weather.
Thanks, ExTank, that's the answer to my original question (thanks everyone else too for an interesting thread)!
Old 12-06-2016, 05:09 PM
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Quote:
Originally Posted by gunnergoz View Post
That isn't quite the case as I understand it. There is no evidence I've seen or read of that the hull plates failed. The iceberg impact would have damaged almost any steel-hulled vessel in much the same way, with the possible exception of a naval dreadnaught (battleship) with fully armored and blistered hull sides...and those didn't come along until a bit later.

The problem was that the damage compromised several compartments, leading to their flooding, and the ship's floatation was no longer assured.

The miracle was that she didn't capsize before going under. That fact allowed the lifeboats to at least be launched. Most big ships that flood, do capsize at some point before finally sinking.
Yah...true. The bulkheads were a HUGE factor in the sinking. But it was also the hull plates and the rivets that were used. From what I've read and seen, especially from Dr. Robert Ballard, the rivets used were cheaper than the ones that were actually going to be used. Being cheaper made them more brittle and inseffiecient.
Old 12-06-2016, 05:21 PM
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Remember the engineers who designed the Titanic class said they were "Virtually Unsinkable".
The press didn't like weasel-words, so they printed "Unsinkable".

This was the first civilian ship to have ANY anti-flooding compartments.

Best laid plans of mice and men...


(these lessons need to be considered in the great rush to autonomous cars...)
Old 12-06-2016, 06:05 PM
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I saw a documentary the proposed a theory that the rivets used on the hull were substandard, and that this what the reason the plates parted.
Old 12-06-2016, 09:06 PM
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Quote:
Originally Posted by bob++ View Post
I saw a documentary the proposed a theory that the rivets used on the hull were substandard, and that this what the reason the plates parted.
I remember it as the rivets were more brittle than the plating but they were as planned. Substandard implies that they didn't meet spec. I believe the problem was the spec for the rivets was different than that of the steel. Which has already been mentioned suffered from unexpected brittleness in cold temperatures.
The rivets apparently failed even before the plates did, at least at the collision points.
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