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Old 16-04-2018, 13:59   #16
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

Empty refrigerator containers can float for a long time. One washed up on Moreton island recently that had been afloat for quite awhile. 6 months I think they said ?
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Old 16-04-2018, 16:26   #17
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

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Originally Posted by Watermann View Post
They don't simply slide off. Twist locks are at all four corners. For each container to container interaction, they lock in just as tight as the spreader bar used on the cranes to lift them on and off the ship. You can find photos of containers almost 90 deg to horizontal and still being held on by the twistlocks. Granted, the weight of the entire box and cargo will have a big role in that. The lowest two tiers above deck (or cell guides, if fitted) are also lashed with crossbars and tightened with turnbuckles (to varying degree). The point of failure tends to be at twist lock connections right above the uppermost lashed container. The containers above that one can exert quite a lever arm and once they get moving side to side, or knocked into from an adjacent wayward stack, enormous forces are exerted on a relatively small connection that subsequently fails. It's rare for a single box at the top of the stack to simply be washed over - unless it was never locked in properly in the first place.

Not all containers have equal heights and stack heights vary for many reasons so it's not as simple to just say to throw a truss over each stack. Early container ships did have lashings alongside the upper tiers that were intended to prevent sway as the ship rolled, but they fell out of favor at some point, probably as twist locks became more reliable. They would also be labor intensive to set and remove.

Intermodal containers are very much designed around their time spent at sea. No other mode, for example, utilizes the lashing points on the rear and sides of the corners - those are solely for lashing bars on ships. Rail and trucks just use twist locks. When packing a container that's going to sea, you pack it to protect the contents during that part of the voyage - it's the most dynamic and usually the longest.

Your last suggestion (higher cell guides) is the most realistic but won't come about without change in regulation (ie, everyone has to play by the same rules so no one loses a cost advantage since container shipping is extremely competitive, even among other kinds of shipping). These guides do allow the lashings to get to tiers higher up, which would exert less leverage on the entire stack as the ship rolls. However, higher cell guides is more steel weight above G, which turns into less cargo weight that can be carried up there. You're also then imposing various container size restrictions within the cell guides (there are containers longer than 40's and they must go on deck at least one tier above the hatches or cell guides).

The industry (at least those of us who actually work on ships) is aware of this and it's been happening a lot more lately as it seems. It's frustrating for us as well. Cargo lost overboard is bad for other mariners, can be bad for the environment, usually damages the ship and of course is bad for our customers. Until ship designs change, and in my view it will have to happen through regulation at the IMO level, all the crews can really do is check & tighten lashings and avoid the worst of the weather as best as possible/practical.
I have seen photos of stacks of containers leaning out like banana peels on vessels that have suffered losses in bad seas and weather. These where obviously not secured top and bottom to adjacent stacks.
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Old 16-04-2018, 22:57   #18
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

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I have seen photos of stacks of containers leaning out like banana peels on vessels that have suffered losses in bad seas and weather. These where obviously not secured top and bottom to adjacent stacks.
Every container is secured to the one below it. Adjacent stacks are not secured to each other due to the reasons I listed in my previous reply (their tops don't necessarily line up).
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Old 17-04-2018, 09:58   #19
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

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Originally Posted by Watermann View Post
Every container is secured to the one below it. Adjacent stacks are not secured to each other due to the reasons I listed in my previous reply (their tops don't necessarily line up).
And this was my point. Containers should be standardized in size, and the extra long ones or shorter ones only loaded in common groups.
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Old 17-04-2018, 17:49   #20
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

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Originally Posted by Watermann View Post
They don't simply slide off. Twist locks are at all four corners. For each container to container interaction, they lock in just as tight as the spreader bar used on the cranes to lift them on and off the ship...

Not all containers have equal heights and stack heights vary for many reasons so it's not as simple to just say to throw a truss over each stack. Early container ships did have lashings alongside the upper tiers that were intended to prevent sway as the ship rolled, but they fell out of favor at some point, probably as twist locks became more reliable. They would also be labor intensive to set and remove.

Your last suggestion (higher cell guides) is the most realistic but won't come about without change in regulation (ie, everyone has to play by the same rules so no one loses a cost advantage since container shipping is extremely competitive, even among other kinds of shipping). These guides do allow the lashings to get to tiers higher up, which would exert less leverage on the entire stack as the ship rolls. However, higher cell guides is more steel weight above G, which turns into less cargo weight that can be carried up there. You're also The industry (at least those of us who actually work on ships) is aware of this and it's been happening a lot more lately as it seems. It's frustrating for us as well. Cargo lost overboard is bad for other mariners, can be bad for the environment, usually damages the ship and of course is bad for our customers. Until ship designs change, and in my view it will have to happen through regulation at the IMO level, all the crews can really do is check & tighten lashings and avoid the worst of the weather as best as possible/practical.


Thanks for taking the time to reply. I learned a lot from reading your post.
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Old 17-04-2018, 18:15   #21
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

Quote:
Originally Posted by Watermann View Post
They don't simply slide off. Twist locks are at all four corners. For each container to container interaction, they lock in just as tight as the spreader bar used on the cranes to lift them on and off the ship. You can find photos of containers almost 90 deg to horizontal and still being held on by the twistlocks. Granted, the weight of the entire box and cargo will have a big role in that. The lowest two tiers above deck (or cell guides, if fitted) are also lashed with crossbars and tightened with turnbuckles (to varying degree). The point of failure tends to be at twist lock connections right above the uppermost lashed container. The containers above that one can exert quite a lever arm and once they get moving side to side, or knocked into from an adjacent wayward stack, enormous forces are exerted on a relatively small connection that subsequently fails. It's rare for a single box at the top of the stack to simply be washed over - unless it was never locked in properly in the first place.

Not all containers have equal heights and stack heights vary for many reasons so it's not as simple to just say to throw a truss over each stack. Early container ships did have lashings alongside the upper tiers that were intended to prevent sway as the ship rolled, but they fell out of favor at some point, probably as twist locks became more reliable. They would also be labor intensive to set and remove.

Intermodal containers are very much designed around their time spent at sea. No other mode, for example, utilizes the lashing points on the rear and sides of the corners - those are solely for lashing bars on ships. Rail and trucks just use twist locks. When packing a container that's going to sea, you pack it to protect the contents during that part of the voyage - it's the most dynamic and usually the longest.

Your last suggestion (higher cell guides) is the most realistic but won't come about without change in regulation (ie, everyone has to play by the same rules so no one loses a cost advantage since container shipping is extremely competitive, even among other kinds of shipping). These guides do allow the lashings to get to tiers higher up, which would exert less leverage on the entire stack as the ship rolls. However, higher cell guides is more steel weight above G, which turns into less cargo weight that can be carried up there. You're also then imposing various container size restrictions within the cell guides (there are containers longer than 40's and they must go on deck at least one tier above the hatches or cell guides).

The industry (at least those of us who actually work on ships) is aware of this and it's been happening a lot more lately as it seems. It's frustrating for us as well. Cargo lost overboard is bad for other mariners, can be bad for the environment, usually damages the ship and of course is bad for our customers. Until ship designs change, and in my view it will have to happen through regulation at the IMO level, all the crews can really do is check & tighten lashings and avoid the worst of the weather as best as possible/practical.
Good post. I'll add that the twist locks are typically around 36 tonnes BS each, same with the lashing rods used on the lower two or three tiers. Most of the upper boxes are empty or very light. Typically (at least on the box boats I worked on) only the lower two tiers held cargo.

At one stage they tried open hatch (Hatchless)full cell guide ships. These worked Ok but had other issues, such as flooding and slow load/discharge.

Loading containers athwartships would be worse as the highest loads typically are in the fore and aft plane due to pitching and pounding.

The system works fine if they are properly loaded and lashed. I sailed through all sorts of crap on those boats and we never damaged a stack.

Checking the lashings was a big task, and one that we took very serously. As an officer I had to sign my name to each lashed stack, and the loss of one signed off by me would likely have spelled the end of my career with that company.

Common issues are heavies over light boxes wheb the port stacks them in the wrong place. Left instead of right handed twistlocks, Poorly tensioned or incorrect lashing systems being used, and broken lashing gear being used.

https://youtu.be/pUle32fSfpw
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Old 17-04-2018, 19:07   #22
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Re: WARNING--Shipping Containers Adrift off N. Carolina Coast

I wonder how much boat it would take to drag one of those to shore. The container itself is worth thousands of dollars. If the contents are properly packed they might be salvageable.
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