Image copyright Getty Images

With South Korea's biggest shipping company filing for bankruptcy protection, the vessels, sailors and cargo of Hanjin Shipping are stuck in limbo, stranded at sea.

Ports, fearing they will not get paid, refuse to let them dock or unload.

That means the ships are forced to wait for Hanjin, its creditors or partners to find a solution.

It's a case of unprecedented scale, with experts expecting the deadlock to last for weeks, if not months.

"[It is] a major disaster for the shipping companies and for the companies that own the goods in those containers," Greg Knowler, maritime and trade analyst with IHS Markit, told the BBC from Hong Kong.

Read more: Shipping giant Hanjin to enter receivership

Peak season

Not only are ships not allowed to unload, containers waiting to be picked up are also being held back by the ports as collateral over unpaid bills.

And even if the ports did allow them in, Hanjin would probably not as the vessels could expect to be immediately repossessed by the firm's creditors.

Beyond the ships and containers, there is of course the cargo within those containers - in many cases part of a tight chain of supply and delivery.

By September, the global shipping industry is already into what is its busiest time of the year ahead of the Christmas season.

"Just imagine, there are some 540,000 containers with cargo caught up at sea," explains Lars Jensen, chief executive of Sea Intelligence Consulting in Copenhagen.

Image copyright Getty Images Image caption The cranes are ready but the Christmas merchandise is stuck at sea

That means that a lot of the goods en route to the US are geared at the busy year-end holidays and any disruption will be a major headache for the companies that have entrusted their products into the hauls of the Hanjin freighters.

Who owns what?

Let's break down the somewhat confusing ownership structure at play here.

Hanjin operates partly with its own ships, and partly with vessels it leases from others. So some of the vessels stuck at sea are owned by other companies who now can't get them back and on top of that have to assume they won't get paid for leasing them in the first place.

The containers on board the ships are also not all Hanjin's own. As the company is part of an alliance with five other cargo firms, there will be a mix of containers on each vessel - some belonging to Hanjin, the rest to the other four partners.

And lastly, there are the firms who own the content of the containers, for instance an Asian electronics firm sending its goods to the US market.

Hanjin's bankruptcy is the largest ever to hit the shipping industry so there's no roadmap as to what will happen now, no precedent of comparable scale.

Stuck in ports

There are the containers stuck at ports.

Image copyright Reuters Image caption Countless containers are stuck in ports around the globe

Let's take a container brought from, say, the Philippines to Hong Kong, to then be picked up from there and taken to the US.

Berthing and handling of that cargo at the Hong Kong port costs money. If Hanjin can't pay that, the port will hold on to those containers as collateral until someone will be willing to pay.

A possible solution would be that the companies who own the contents of those containers ask other shipping companies to step in and pick up where Hanjin left off. The cost of this would be immense, and would come on top of anything they had already paid to Hanjin beforehand. Part of it might be covered by insurance but it would still be an extremely costly endeavour.

Stuck at sea

The containers stuck on board the ships are the next problem. While at sea, there is no way to get the cargo off board.

Ships that are only leased by Hanjin could see their actual owner take back control and bring them into a harbour. They would still need to be cleared of their cargo but could then be leased to other companies.

Given that the owners of any leased vessels would probably not want to foot the bill themselves they may try to draft in the four partner lines that have containers on the ship or maybe even the companies whose cargo is inside those containers.

Image copyright Getty Images Image caption Hanjin's bankruptcy is the largest ever to hit the shipping industry

The ships owned by Hanjin itself would most likely have to be sold before anyone would bring in the money to get them into a port and cleared. The fact that they would have to be sold as is, i.e. at sea, and with a load of overdue containers on board would probably weigh down the price of the vessels.

Stranded sailors

Each stranded ship has about 15 to 25 crew on board. Unable to call at any port, they will have to depend on the supplies they have with them until a solution can be found. While food should last long enough, they will eventually need fuel.

In a worst-case scenario, should they find themselves unable to pay for fuel being delivered by a shuttle, they would risk running into serious trouble. In that case though, nearby ports would likely be forced to accept them.

Aside from the prospect of being stuck for weeks at sea, the sailors will also face uncertainly over their wages. Most of them are not actually hired by Hanjin but by crewing agencies. Those agencies are unlikely to get paid by Hanjin and therefore won't be able to pay the crews.

"Unless someone steps in very quickly - and there is no sign of that - this will last a very long time," according to Mr Jensen.

Ships, cargo and crew might find themselves stuck for weeks, if not months, without knowing when and where their current voyage will end.