I have never seen a or heard of anyone seeing or hitting a container. However, it's a natural concern, just like falling into a sink hole or the road/bridge collapsing while driving. The odds are probably less for hitting a container.
Whale are a different story or at least "Whale Sharks". I hit of of those blubbery masses at sea one time. We were 3 days out of Darwin, Aust, bound for Christmas
Island (S of Indonesia). We were sailing in 10-15kts of wind
astern and probably doing 5kts. It was mid-day and I was sitting in the cockpit
. All of a sudden, the boat just came to a skidding stop, everything went flying and Kanani just shuddered. My immediate thought was that we must have hit a sand bar, then I thought, "Impossible, it must be a big fishing
net". About that time, this huge greenish, spotted mass came rolling up astern. It was a Whale Shark. He rolled on his back and gave out a big BELCH
. It was the worst smell that I have ever smelled in my life.
We were very fortunate to have a modified full keel
with a very heavy skegg-hung rudder
. The day after this incident, we were becalmed in the morning and I jumped in the water
to check for damage. Other than long, deep scratches in the paint
(obviosly from barnecles) we were fine.
That same day, we saw another Whale Shark floating on the surface. It was a pretty scary feeling for a while.
I have heard a lot of stories about boats hitting trees and logs
in the North-West US. That really is a concern. There is always the story (that most have heard) about the guy that hit a refridgerator off of the coast. He towed it to the marina, tracked down the original owner and notified the police.