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Old 25-06-2015, 02:00   #31
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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... the standards to which they are now constructed requires them to flood and sink when immersed.
I [blurrily] remember chatting to a wharfie at a pub one evening who informed me that the containers are required to have a dissolvable plug(s?) that allows them to flood once immersed for a period of time. Can't remember specifics as it was fairly well into the evening when I was chatting to him.
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Old 25-06-2015, 02:01   #32
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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And just thinking about this a little more.

A typical container in the U.S. Is 40'x8'x8'. That's a displacement of about 160,000 pounds of water. I suppose the average container hauled by a truck, at least, does not contain much more than 40,000 pounds. So it should float very high. (Hope I got the math right)

I suspect the dreaded container awash, with just a couple of inches above the water, is a rare thing indeed.
They are required to have holes in them so that they will flood and sink.

This does not work in 100% of cases, however, because some containers are full of voluminous low density things.

I doubt if any lost container will float high, however, when it's partially full of water, and with quite a bit of dense steel tare.
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Old 25-06-2015, 03:04   #33
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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They are required to have holes in them so that they will flood and sink.

This does not work in 100% of cases, however, because some containers are full of voluminous low density things.

I doubt if any lost container will float high, however, when it's partially full of water, and with quite a bit of dense steel tare.
No they aren't...
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Old 25-06-2015, 03:27   #34
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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You are Not going to see it at night, period. Small chance of seeing it in the daylight. Odds are in your favor but there is always a chance, sorta like having a tree fall on you ashore. That doesn't keep you inside does it?
I think the chances of seeing a container awash in time to avoid it, even in broad daylight, are close to nil. Low in the water it will not be visible until you are quite close to it, and even if it is visible in time for avoiding maneuver, no one watches the water just ahead of the boat without blinking, when offshore. We do look out like this in coastal waters where there is a risk of crab pots, but not offshore.

I think the falling trees are an excellent metaphor. You don't stare up at the trees as you walk down sidewalks, in order to try to dodge out of the way in case one starts to fall on you. If a tree falls on you, then you're just dead, that's it. Goes with the territory.

That being said, I think it's prudent to build boats with bows which can withstand collisions without sinking. That means watertight compartment in the bows and reinforced hull, which is fairly typical on good boats. One corner I don't like seeing cut is to have the anchor locker open to the forepeak, and then, even worse, to have thin, single-skin layup in the bows, something we've seen in some boats like Benes which are otherwise intelligently designed.
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Old 25-06-2015, 03:44   #35
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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No they aren't...
I've read this in dozens of places. If it is an urban legend, I will be glad to be corrected.
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Old 25-06-2015, 03:52   #36
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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I've read this in dozens of places. If it is an urban legend, I will be glad to be corrected.
OK consider yourself corrected... 'boxes' don't have holes in them.

Its a bit like when you go to the movies and they scuttle ships by opening the 'seacocks'..... ships don't have seacocks..

Mind you if the condenser intake in a steamship fails for whatever reason you will have 'issues'...
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Old 25-06-2015, 04:08   #37
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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OK consider yourself corrected... 'boxes' don't have holes in them.

Its a bit like when you go to the movies and they scuttle ships by opening the 'seacocks'..... ships don't have seacocks..

Mind you if the condenser intake in a steamship fails for whatever reason you will have 'issues'...
Hmm. I think warships have, or used to have, Kingston valves for flooding the magazines, if not actual scuttle valves. And all ships have sea chests or some other way of taking in sea water for different purposes, which can be used for scuttling -- just close the valve, unbolt the manifold, pipe or whatever, and "open the seacocks". I don't see what's so unrealistic about that.
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Old 25-06-2015, 06:12   #38
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Re: how to detect CONTAINER lost at sea and NOT hit it?

There is an ISO standard for shipping containers. Here is some info . . .
Are shipping containers wind and watertight?

Hide Answer Yes, very. Shipping containers are made for transporting goods across the oceans – often on decks of ships. They have heavy duty rubber door seals which keep out the elements. Used shipping containers sold into the storage and the re-use market can have damaged door seals or damage to the steel roof or sides but most companies selling used containers will ensure that they are inspected and repaired before they are delivered or released. There are low grade containers around which have usually been sold and used before and then sold on again. These containers will often be at least 15 to 20 years old and whilst some of this age can be in very good condition there is a risk that there may be corrosion or damage to doors, sides, roof etc. It is a case of ‘let the buyer beware’ and ‘you get what you pay for’. There is a strong market for new and used shipping containers so expect to pay a fair market price for a good wind and watertight container.



The doors apparently have rubber seals, but it is not clear if they are expected to be "rain tight" to protect freight, or water tight as we expect the hulls of boats to be.
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Old 25-06-2015, 06:45   #39
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Re: how to detect CONTAINER lost at sea and NOT hit it?

The floors of a standard container are not watertight. The wood leaks. Carried hides in brine for years. Got dripped on by the disgusting rank brine leaking through the floors. the ship's used to stink as the mess rotted and festered in the sun.

The doors need to face aft to reduce the chance of water ingress so this implys that they are only weather tight, not watertight. Never seen any disolvable plugs, and the amount of water a box boat throws across the bows when punching into a force 10 would quickly desolve any plug.

Air bags are used to help pack containers, but most of the top tier boxes are empty, anyway and they are the most likely to end up in the drink. If empty they would sink pretty quickly methinks. A tanktainer might float for a while, and a refrigerated box would be a hazard for a long time, as I suspect it would be positively buoyant with all the foam insulation.

As I said, in six years with P&o containers we lost one stack in the 26 strong fleet, and this fell inboard not over the side. The lashing system really is pretty solid. All the top boxes are empty. Biggest issue is wrong handed twistlocks, and ports loading boxes in the wrong slots, Resulting in heavies over light boxes.

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Old 25-06-2015, 06:56   #40
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Re: how to detect CONTAINER lost at sea and NOT hit it?

So, I'm sticking with they'll mostly float high until they sink. The perfect combination of trapped air or bouyant contents, such that they'll float barely above the surface, very rare indeed.

Stop worrying about containers.

Worry about lightning, instead.
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Old 25-06-2015, 10:35   #41
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Re: how to detect CONTAINER lost at sea and NOT hit it?

Containers are not water tight, they are weather tight. Even refrigerated containers will leak water if immersed. It may take a day or two, but a container will fill with water and sink in short order unless its contents keep it afloat. if the container is stuffed with high buoyancy items it can stay afloat but just barely, do a displacment calculation.

There are no auto opening valves or purpose built holes to get them to sink. If they were meant to be water proof, they would be built as all steel construction without wood floors and the doors would be massive with close spaced 'dog's all around like a water tight bulkhead door on a ship.

To make you feel better, a guy who works for a shipping company told me they lose thousands of containers overboard every year.
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Old 25-06-2015, 11:30   #42
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Re: how to detect CONTAINER lost at sea and NOT hit it?

Every now and then they lose a container or two from ships waiting to go into Durban harbour. Most of them sink fairly close to the ship that they came from. They make very good spearfishing spots.
Ive also been on a couple of ship salvage jobs. The containers that are under water are all flooded. I really think that the danger that they pose is very small.
Whales are probably a much bigger concern.
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Old 25-06-2015, 11:42   #43
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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Originally Posted by Dockhead View Post
Hmm. I think warships have, or used to have, Kingston valves for flooding the magazines, if not actual scuttle valves. And all ships have sea chests or some other way of taking in sea water for different purposes, which can be used for scuttling -- just close the valve, unbolt the manifold, pipe or whatever, and "open the seacocks". I don't see what's so unrealistic about that.
We aren't talkin about the flooding of warship magazines here we are talking about the popular misconception that merchant ships have 'seacocks'.... they don't. In WW2 german blockade runners could be scuttled at short notice but that was a bit of a special case. On a traditional merchantman it would be possible to downflood via the bilge lines after removing the non return valves but they do not have 'seacocks' as beloved by John Wayne and others.
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Old 25-06-2015, 11:49   #44
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Re: how to detect CONTAINER lost at sea and NOT hit it?

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The floors of a standard container are not watertight. The wood leaks. Carried hides in brine for years. Got dripped on by the disgusting rank brine leaking through the floors. the ship's used to stink as the mess rotted and festered in the sun.

The doors need to face aft to reduce the chance of water ingress so this implys that they are only weather tight, not watertight. Never seen any disolvable plugs, and the amount of water a box boat throws across the bows when punching into a force 10 would quickly desolve any plug.

Air bags are used to help pack containers, but most of the top tier boxes are empty, anyway and they are the most likely to end up in the drink. If empty they would sink pretty quickly methinks. A tanktainer might float for a while, and a refrigerated box would be a hazard for a long time, as I suspect it would be positively buoyant with all the foam insulation.
........
...
Reefers would be an issue as you say .... although I'm not sure what volume of insulation would be required to float the weight of the steel.

Wet hides? horrible things.... but I imagine that would be a corrosion issue with the 'juice' having destroyed the steel of the floor under the 'dunnage'..... boxes used for hides probably stayed in that trade... I can't imagine using them for anything else.
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Old 25-06-2015, 12:04   #45
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Re: how to detect CONTAINER lost at sea and NOT hit it?

An overview of lost container numbers from last year.

How Many Shipping Containers Are Really Lost At Sea? - gCaptain
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