Watertight doors

[Philip Bowler]

Holds obviously not allowing for the volume of cargo within!
A 5300 tonne cargo hold is massive even by todays standard. 5300 cubic metres?
Your figures come from where? Assuming a specific gravity of? 1025 for standard sea water? 1000 for fresh water or somewhere in between as there was likely to be fresh water mixed with salt in the vicinity of the berg.
Canberra had a forepeak tank holding (as far as I remember) 450 tonnes of Fresh water. At 45000 tons and built of lighter material she was bigger. Your figures are, I feel, slightly excagerated, 29750 tonnes of water? I'm amazed that it stayed afloat for 2 seconds let alone 2 hours!

 

[Noel F. Jones]

It is not clear whether Daniel Foerster's figures allow for the attribute of permeability.

Permeability = available volume/total volume

The forepeak can be taken as 100%.

Regarding machinery spaces, there are standard notional permeability ratios. Post-design, it should be possible to arrive at an actual percentage permeability and this should be available to the officers via the hydrostatic curves provided by the builders and posted in the ship.

As for hold spaces, there is also a standard permeability ratio for general cargo. However, this would have to be reconciled with the prevailing condition of lading.

The values for Titanic would of course reflect a seawater operating environment. The effect of any variation in specific gravity due to the presence of ice would be marginal.

As for the time take to founder, presumably these figures represent the fully developed casualty and do not reflect the rate of ingress.

Noel

 

[Daniel Foerster]

Hi!

I posted this tonnages because of Mary's question "I don't know if this is possible mathematically, but how much would the water filling one compartment actually weigh?"

The data is quoted from the Bedford & Hacket paper from 1996. The tonnage is not for the Holds and Boiler Rooms only, it also contains the whole space above up to C deck. The tonnes are metric (1000 kg). The used permeabilities were 0.7 for spaces forward of the boiler rooms and 0.85 for the boiler rooms.

Titanic's lightweight was 39,380 tonnes, her deadweight 13,767 tonnes. At the time of the collision she displaced approx. 49,000 tonnes.
She foundered after loading approx. 40,000 tonnes of water, so she displaced about 90,000 tonnes at that time.

 

[shawn sparkman]

if plans would have been better made the water tight compartments would have been topped off with effecient pumps to control the water mass entering the ship. even so, survivability is still in question

 

[Michael H. Standart]

Shawn, the design of the Titanic was as good as they came for the time and in terms of watertight subdivision, better then most ships then, and even superior to most vessels...excepting warships...today. I doubt very much that you'll find even one liner/cruise ship which has as much in the way of watertight protection as did the Olympic class liners. (And no, this dirty little secret isn't the sort of thing you'll see Carnival or Princess Cruises advertising in their brochures...for obvious reasons!)

That's not to say the design was perfect. It wasn't, and nothing built by the hand of man is or ever will be. The very dirt simple and strieghtforward fact is that the Titanic wasn't killed by faulty design. She was killed by the one single factor that has caused more carnage then any other; Human error.

 

[Daniel Foerster]

Michael, to my knowledge modern passenger vessel of Titanic's size have to comply a three compartment standard and to fulfil damage stability requirements that were not met by Titanic.
This are minimum requirements that are normally treated as the maximum with very little margin to spare in contrary to Titanic, where the Builders went well beyond what was required at that time.
In addition the pumping capacity of today's vessels is much higher than 1912. Probably some vessels could float on their pumps today if damaged like Titanic.

 

[Erik Wood]

Daniel said Michael, to my knowledge modern passenger vessel of Titanic's size have to comply a three compartment standard and to fulfil damage stability requirements that were not met by Titanic.

Most of today's passenger vessels are one compartment ships with the exception of the new carnival builds which are two compartment ships soley because of the plant layout. I can't speak for the QM2 or QE2. The Independence has or had a three or four compartment design similar to Titanic.

There are more stability requirements then there are damage requirements, the main reason being that it is the view of todays world that you should be able to see and avoid danger without hitting it, there are far more regulations about how to avoid it then what to do when you hit something.

SOLAS and U.S. Port State Control Inspections carried out by the Coast Guard manadate the ship be at least a one compartment ship inregards to flooding and a two or three (depending on size) for fire. To my knowledge these types of regulations didn't exsist in Titanic's day.

Daniel said:In addition the pumping capacity of today's vessels is much higher than 1912. Probably some vessels could float on their pumps today if damaged like Titanic.

This is sort of true but is also very misleading. Ships today have a much larger pumping capacity because ballast is used for stability much more frequently and in different ways then in 1912. The sinking of the Oceano's, the Archille Lauro (although the loss was primarily by fire, the list the ship took due to internal firefighting and flooding was the main reason for abandonment) would seem to indicate that the pumps where unable to do the job that was required of them. Unlike Naval ships all of the passenger ships that I have served on did not have have a large scale pumping ability. They did have the ability to shift ballast as well as to pump certain compartments (main space only) dry or hold the flooding at what is at, but they did not have ability to pump themselves dry.

 

[Michael H. Standart]

Erik has covered most of the ground. I'll just add that the Titanic was built to up to a four compartment standard.

 

[Erik Wood]

In addition to my last post:

There is no such thing as a watertight compartment, water will invade the compartment, it is only a matter of time. That is why techniques for shoring and peaking where developed in both World Wars. The information that was gained from Titanic was used to a extent in future designs, until the mid to late 50's, when fire became the big evil. Ships have fire doors that provide temporary blockage of water and fire, this system was put in place after it proved very effective on aircraft carrier hanger decks.

The emphisis today is more on prevention, that being said ships like the Carnival Conquest and her sisters are probably some of the more stable ships of the new era. But how this came about was not by design in case of damage, but necessity.

With the invention of the azipod one compartment now does two things which require seperation in the event of an emergency, where in the past the jobs done by one piece of equipment took up to 4 pieces of equipment. Because of the design and layout of main spaces it is now necessary to put a water/fire resistent barrier between the two compartments. This is only a temporary solution to a much larger problem. On most ships the main space runs a third of the ships (make that passenger ships built today) length with associated compartments only sealed by "dogged" doors in case of emergency. If you where to loose the main space the ship would become far to unstable, when I say loose, I mean flood. Fire is a different beast all together.

Now main space areas are usually confined to four seperate compartments divided by fire doors, with only one being completed sealed by a set of double doors. The first is main control, which is sealed via "dogged" door from the main space, this door is also usually a lesser form of a fire door as well. Then there is the main space, which is sealed by a set of watertight doors and fire doors from the "pod" compartment and by a "dogged" door from main control and usually another set of "dogged" doors on either side of it. Assuming the ship is not a steam ship, one door leads to what is frequently referred to as "AUX 1". This is where extra machinery is kept, i.e. sewage, garbage, plumbing, hot water tanks and the like. The second door leads to a seperate control center in case of the loss of the first (a lesson learned and implemented by the NTSB after the Columbia Ferry Fire in Alaska) and the rest of the machine spaces. If I had the intelligence and know how on how to draw a picture and post it I would.

My point is that watertight compartments do not signify a ship to be safe, nor does its pumping capacity. What makes the ship safe, is it's abiltity to stay in a stable condition when the internal workings of the ship are damage or extra weight is added or removed from sections of ship, but not within the rest of the ship.

In computer models ships fitting the Carnival Conquest design were able to loose it's main space and remain afloat and stable in a sea state up to 5 feet.

What also makes design so important these days are the heights of the superstructre compared to the displacement of the ship. The tops of ships including the newer ones are made of a lighter material then the rest, making it a gigantic sail in windy conditions. This also has to do with watertight compartments and how they are designed.

 

[Michael H. Standart]

And in making a ship safe, it also helps not to hit solid objects that move out of the way for nobody. Titanic learned this lesson the hard way.

 

[Samuel Halpern]

On warships there are, in addition to watertight doors (WTDs), doors marked as airtight doors (ATDs). I assume they are to prevent the spread of fire and gases. Anyone know how they differ from WTDs? The WTDs and ATDs I've seen recently on an amphibious assault ship look very similar to each other. All are operated by hand.

 

[Daniel Foerster]

Erik said There is no such thing as a watertight compartment, water will invade the compartment, it is only a matter of time.


What do you mean with "it is only a matter of time"? Surely nothing is for eternity but the watertight compartmentation should help the ship to float until it reaches the next port (if still manouverable). I.e. as it was after the Olympic/Hawke collision.


The tops of ships including the newer ones are made of a lighter material then the rest, making it a gigantic sail in windy conditions.


Seeing this high towering vessels I ever wondered if there are operating restrictions in bad weather?

 

[Charles B. Weeks Jr.]

Naval vessels and commercial vessels are built for different missions, therefore they have different degrees of subdivision. The warship which is intended to go in harms way will inevitably be more finely subdivided, it helps to limit the extent of damage. While the commercial vessel has more large open spaces, to facilitate handling of cargo or passenger activities. A war ship may well have more than one deck which can be sealed watertight. On a merchant ship one would expect to find only the main deck capable of being closed watertight. Both types of ships have transverse watertight bulkheads, the warship having more than the merchant ship. Longitudinal watertight bulkheads being rather out of favor except to divide liquid tanks. When flooding occurs they tend to cause large lists, such as in Lusitania, Empress of Ireland and Andrea Doria.
Regards,
Charlie Weeks

 

[Michael H. Standart]

It's been awhile, but the watertight doors I recall seeing were more ruggedly constructed and also had beefier gaskets then what you would see with an air tight door.

On "it's only a matter of time", much would depend on the nature and extent of the damage the ship suffered. The strength of these doors is only as good as what's supporting it. When a compartment is flooded, there is a lot of weight and pressure that's put on the thing, and it won't hold up forever. Withour remedy and repair, eventually, it'll give up the ghost. The whole idea behind this sort of subdivision is to contain the flooding, fire, or both so the crew can buy time to fix the problem, make a safe port where repairs can be effected, or make it possible to safely evacuate the ship.

 

[Erik Wood]

Mike hit upon Daniel's question to me, but I would further say this. In order for a compartment to be truely watertight it has to be somewhere out of water with no rain. Steel "bleeds" to certain extent. Seems open up, parts of bulkheads begin to seperate as the water pushs on certain parts of it, bending it.