I have done on average 12,000-15,000NMs at sea per year since 2002, and I don't know how many miles before that but still quite a bit. I saw a floating container (and almost ran it over) 1 time and that was 19 years ago. The only way I saw it was I avoided a 100' patch of seaweed and it was floating in the seaweed with only 4-6" of the container above the waters surface.
The odds vary greatly by where you are and when as well. If you're in the Indian Ocean when the M/V Comfort sinks then it's one thing, but if you're cruising the East Coast of the US the odds go down considerably. Even then you'd have to be the first one to reach it or not have your radio on. Far greater odds of problems on a river and a tree coming down the river or logs in Alaska. Far greater odds of disease hitting while you're at sea or all your systems going out. So, yes, containers are something to be aware of their possibility, but not the top concern boaters face, nor even one of the major threats. Even in the Indian Ocean where many have been lost, I'd be more concerned about pirates than containers.
I also have come across submerged or neutral buoyancy containers floating just below the surface whist at sea. 25 years ago in the Florida straits ( multiple containers ) and again in the late nineties off of central Americas Pacific coast. All you see is a flash of color until you pull the sticks back and get a good look as the blood drains from your face as to what could have been. The deal is that it wouldnt have mattered in my vessel was doing 5 knots or 15 knots and made out of any of the materials mentioned before, simple outcome would be that the boat would have been an ash tray on the bottom. No if's butts or doubts. That being said, it's just the chance that the odds of a collision happening are relatively slim or the actual percentages of reported collisions are few. It would be interesting to track how many sightings are radioed in to the maritime authorities and how many notice to mariner warnings are issued each year.
Loosing a box We have lost 12 boxes in the last 7 years. 7 of them were lost during a tropical storm from a single ship, when the ship was hit by rogue wave on our far east route. These boxes were all TEUs and located on the first column, top row on the bow of the ship and all were empty boxes. Because of the big wave, all boxes were severely damaged and went directly to the bottom of the sea. The ship lost also the forward mast and two mooring line drums.The other boxes, 2 x 40 ft boxes and 3 TEU, got lost during high seastate (no gail force storm) from different ships and routes. All those were empty soft tops and the reason for loosing them was the twisting of the ships during that seastate and the different stability of the hard boxes and the soft tops. All those single losses were located on the last row. The lashings broke and off they went and none of them remained afloat. After that losses we have changed our loading SOP regarding positioning of empty boxes, especially soft tops and changed to more heavy duty lashing hardware. No more losses have been ecountered since that new SOP was implemented. The official figures of lost boxes are most likely incorrect or at least incomplete with a pretty high number of unknown cases. Several sea going nations do not report their losses for prestige reasons because they are "infallible" and some shipping companies do not report lost boxes with their own label on it. A lost empty box out of your own stock of boxes in not worse the paperwork. Floating boxes are very hard to detect on the oceans especially during night. Only a special broadband, short range radar, purposely mounted on the bow and tuned to detect floating objects may, I say again, may see a floating box, if not completly submerged. If floating boxes are reported with pretty accurate position and the skipper places a seaman with a big search light and radio on the bow, at 20+ Kts, at time of detection, there is no time for evasive maneuvers anyhow. And a floating box will not sink or really damage a big ship. Sailors are much more in danger, especially circumnavigators or passagemakers with their smaller boats. On some of them with only small crew or on single handed crossings, nobody is on watch and the boat is on auto steer with tradewind sailing gear (is their a recent Hollywood film comming into my mind ). When they hit a floating box at 8 or 10 Kts while asleep, they will never know what or who sunk them. But taking the total ocean covered area of our planet in account with the total number of ships, especially (smaller) sailboats, chances are rather small, hitting a floating box. Statistically, the probability hitting a sleeping whale during an ocean crossing is much higher than hitting a floating box. The computer program we are using in a field test at the moment is pretty useless up to now, because the number of actually floating boxes, equipped with an GPS tracking system, is close to NIL. Navigare necesse est, vivere non est necesse or in short english version: No risk, no fun
