What's the difference between an 'allision' and a 'collision'?

I have to admit that after a lifetime career at sea I’d never heard the term ‘allision’ until I started reading this web site where it’s used regularly. Do people really talk like that? Do people ask you what you’re talking about when you say it? Is it primarily American?

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It’s the language of the NTSB, that’s how I know the term. I even find it a slightly useful distinction, but I would never use it in daily speech.

Thanks. I had a guess but had to look it up online.

It’s a common term in Maritime Law.

The original poster who used it might object to being called “American.”

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It may be commonly used in US Maritime Law settings but not as common anywhere else:

Um, I didn’t call anyone anything. The site is US-based and the term has been used a few times and that was my American connection. The American connection was also used in online dictionaries although my hard copy dictionaries (US and British) make no mention of the word at all which tends to make believe it is a newish fad perhaps.

Thanks. That’s a better explanation including the US connection. So it’s not a new word, but its increased usage might be.

Most commonly this is another ship, perhaps at anchor or docked, but it can also refer to a ship hitting a fixed object such as a wharf or a bridge. For you and me, that’s a collision, but US law reserves that word for an impact between two moving ships.

Calling striking a fixed object a “collision” sounds wrong to my ear. I went off the road and collided with a tree? Hit or struck sounds better. A “collision” implies the other object was moving.

Further, less strongly, the term ‘struck’ implies that the allision was insufficient to end the action while “hit” might have stopped the moving object. “I went off the road, struck two trees and ended upside down in the creek.” vs “I hit a tree and totaled the car”.

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I never heard the term “allision” until I started working in the insurance side of things. Now, I use it all of the time. As stated above, I have come to use the term when a fixed object is struck. For me, most of the time it is platforms. . . . .

“co” does imply that there are two things actively involved, I think. I don’t use the term ‘allision’ at all except when I think people on the deck side are listening and I want to avoid them saying, “well actually…”

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Nothing wrong with “allision” that I see but to avoid triggering the pedantic types and general critics “struck” would have been a good word.

If a ship “hits” a pier, to my ear at least, it stopped the ship, on the other hand if the ship “strikes” something it implies that the ship kept moving. An allision could be either case but has the disadvantage of creating a distraction from the topic.

Allision – Nautical Word of the Day -gCaptain post from 8 November, 2007

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Allision – the striking of a moving vessel against one that is stationary. – International Maritime Dictionary, de Kerchove 1948

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Here is from the gcaptain post: Allision is a “violent striking” so in the case of the ship and the container crane “allision” fits the case more precisely.

Allision is a violent striking (such as in a collision) with a fixed object. This is in contrast with “vessel contact” with a fixed object such as would be made with bridge fenders in the ordinary course of say a tug and barge passing under a bridge.

Bridge owners would prefer to classify all vessel/bridge interactions as “allisions” when fender systems have not been maintained and simply fall apart upon incidental contact, or were never properly designed.

The right of navigation generally supercedes the right of the bridge to obstruct the waterway. Bridge fenders are intended to protect the vessel, not the bridge. Congress allowed the bridge to be constructed with the provision that navigation would not be interfered with.

Under the “Oregon Rule” the burden of proof is on the moving vessel to prove that the allision was the stationary object’s fault. This might be shown, for example, if the fender was encroaching upon the navigation channel either from damage, or in some cases because it was not built or repaired according to the permit.

The source of the Oregon Rule.

Some other presumptions in Maritime Law:

The Pennsylvania Rule (vessel in violation of navigation statute presumed to be at fault)

The Louisiana Rule (vessel adrift presumed to be at fault)

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Maybe one allides alone but collides in collusion.

Slight coming together.
Or was that the Karma Sutra?


How Freudian of you.

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I collided with a ship once just before I allided with a pier.

English Channel pilot once told me they didn’t consider ship collisions even worth talking about unless they involved three or more ships.