Friday, July 10, 2020

Are Shipping Containers Lost at Sea a Major Hazard - or Is the Case Overstated?

All Doubts Might be Easily Eradicated Using Available Technology
Shipping News Feature

WORLDWIDE – For the last decade or so the World Shipping Council (WSC) has taken a keen interest in the number of containers lost at sea, and since 2011 has surveyed its members annually to try and get a grip on the figures. What this has evidenced is that, despite peaks and troughs dependent on the number of serious maritime accidents, the percentage of boxes lost overboard represent a tiny fraction of those carried.

Why then the interest if the loss factor accounts for an average of less than one thousandth of 1% of the roughly 226 million containers currently shipped each year? The answer is really twofold, firstly the dangers when the cargoes represent a genuine hazard to the marine environment. Some of the losses arise for reasons directly attributable to hazardous cargo, often misdeclared, and possibly flammable.

The second reason is the theoretical possibility that a 20 or 40 foot shipping container has the potential to drift, possibly for years, sub surface, a long lasting threat to any vessel passing above. Although this factor has been dismissed by many in the past as presenting virtually no danger, as with whale strikes, whilst a merchant ship may encounter such a hazard and probably escape with little damage, that is not always the case for smaller craft.

Racing yachts seem to be the type of vessel most at risk, with several reporting accidents which bear all the classic hallmarks of running into a square edged, solid object at speed. Additionally some skippers have had near misses where they actually managed to veer off and avoid barnacle covered containers, wallowing with barely a couple of inches above the waterline.

Certain containers and cargoes have more of a propensity for buoyancy, reefers with their hermetically sealed doors, and boxes containing sealed packages with lots of foam or polystyrene inside are good examples. However the only study of container buoyancy we could find, was by Jonathan Ridley, Head of Engineering at Solent University’s Warsash School of Maritime Science and Engineering University.

Ridley concluded that the subsurface danger is a myth and that there will virtually always be part of the box visible above the surface, saying:

“I did a lot of tank tests on this, and that [semi-submersion] is actually physically impossible. It might be that a wave washes over it, and it can float very low in the water, but once a container actually goes beneath the surface of the sea, the air inside the container gradually gets compressed and gets less buoyant, so it sinks.

“They could sink within days, or they could be several months still afloat, it depends on the type. All have doors with rubber seals and when their rubber seals start to break down you’re going to get water in. The containers’ major structure is in their corners, the side panels have a minimum thickness of 1.6mm, which is not a lot for steel.

“So if a container falls off the side of a vessel the twisting torsion on it is probably enough that the container would fail. A container with moving cargo inside is likely to suffer a loss of structural integrity fairly quickly in waves. But it could be just a couple of inches above the surface, and if it’s filled with the right amount of polystyrene, it could stay there forever.”

Despite these theories the WSC continues to take the problem seriously. Nobody wants to lose anything overboard, particularly since the French authorities decided in 2014 that the 75 loaded and 442 empty containers washed from the Svendborg Maersk in a stormy Bay of Biscay were the responsibility of the Danish shipping company.

Four months after the incident the French decided that the sunken boxes presented a risk for their fishing fleet, always a hot topic in Gallic realms, and it ordered Maersk to locate every single one of the missing boxes, setting a precedent in terms of responsibility for the line and its insurers.

There are of course ways of dealing with the problems associated with these missing containers, assuming those responsible are prepared to adopt them. Firstly the sheer size of the new breed of container ships somewhat contra-intuitively means serious accidental losses overboard are less likely, although the additional problems of wallowing in heavy seas are worsened, but can be mitigated by the correct steerage instructions.

The wider beams of the huge 20,000 plus TEU vessels make a more stable platform and safer lashing blocks, although the perennial problem of poor quality lashings and damaged corners and twistlocks remain. Additionally devices such as the Containersinka, patented by Tony Priestly can be retrofitted to a box for under $10 and will ensure it disappears completely beneath the waves in less than 6 hours. As yet nobody seems to have adopted the technology which floods the box using a simple U bend valve entry to allow the ingress of water.

Then there is underwater location technology, using EU funding Ladar UK, an Anguilla registered subsidiary of GMS Global Maritime Services is working on producing sub surface radar sweeps ahead of a vessel to detect unseen threats day or night. Despite the doubts about just how much danger submerged objects represent it seem the EU has been willing to invest over €2.5 million in the tax haven registered company’s trials.

The latest WSC report ‘Containers Lost at Sea – 2020’ can be downloaded HERE.

Photo: Damaged containers on board the Svendborg Maersk following her accident in 2014. (Courtesy of the Danish Maritime Accident Investigation Board) with (Inset) a Containersinka, the development of which was apparently partially funded by Maersk Line.