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Submerged Shipping Containers: Avoiding a Collision

Submerged shipping containers: How to avoid hitting one, and what to do in the event of a collision.

shipping containers falling off a ship

Here’s an uncomfortable fact. Every year a not insignificant quantity of shipping containers are lost overboard due to adverse weather. Most of these sink, but a few, filled with light cargo and packing material, stay afloat. Since containerization has been around now for forty years, you would think the cumulative effect would be staggering. Yet there do not seem to be that many incidents with yachts and containers.

What got us thinking about this is a news report a few days ago that the leading single hander in the Vendee Globe Race was adjusting his course to avoid an area where containers were lost a week ago.

The first time we heard a yacht vs. container story was about a wooden sloop in the New Hebrides (now known as Vanuatu) in the Western South Pacific. They tore a large hole in their hull and began to quickly fill with water. The crew managed to get the life raft free, and were eventually rescued.

This was 1978, and we were in the same area with our fiberglass production yacht. Lots of through hull fittings, no watertight bulkheads, and we were not prepared to abandon ship in less than a minute.

Although we do not obsess about containers – the risk is probably less than a drunk driver crossing the center divider and colliding with you – we do acknowledge they could be a problem.

If if is calm, and you are watching, you might see the container. If there is a sea running and whitecaps, the disturbed wave pattern would be a clue. Calm conditions with a good quality radar and there might be a blip (the bigger the antenna the better for weak target detection). Our experience with sonar is that it would not give you warning because of sea clutter. In all these regards spotting a container seems to us to be a lot like finding bergy bits (small chunks of ice).

Bottom line, don’t obsess, keep a good watch, and have an abandon ship plan that works in under a minute.

If you are designing, building, or buying a new boat there are some other considerations.

  • Have a collision bulkhead forward.
  • Integrate tanks with the hull so they form a double bottom.
  • Provide extra reinforcing in the stem (bow) so the bow can ride up and over the debris.
  • Have extra laminate in the turn of the bilge (also helps in a grounding).
  • Provide extra strength keel support (floors) and bolts (we use four times the American Bureau of Shipping scantlings). Avoid keels with bulks or wings.
  • Have a watertight bulkhead aft to protect from flooding caused by a damaged rudder or prop shaft support strut.
  • Design rudder and related to twice the ABS rule.

All of the above also pay dividends when you are aground, or suffer a collision with another vessel; there’s also a psychological benefit in knowing you have the highest factors of safety working for you.

And if you have a stock production boat without any of these features? As we said before, the odds are heavily in your favor. But just in case, be prepared and practice abandon ship routines.

partially submerged shipping container

We’ll end on a positive note. In the last 300,000 or so miles, keeping relatively careful watch most of the time, we have yet to see a container.


Posted by Steve Dashew  (February 9, 2009)




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