A ray located opposite middle of ship

I believe the answer is:

abeam

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'a ray located opposite middle of ship' is the definition.
I can't judge whether this definition defines the answer.

'a ray' is the wordplay.
'ray' becomes 'beam' (synonyms).
'a'+'beam'='ABEAM'

Can you help me to learn more?

(Other definitions for abeam that I've seen before include "Set across" , "At right angles to ship's length" , "At right-angles to keel" , "across width of ship" , "In a line at right angles to a vessel's length" .)

I've seen this clue in The Daily Mail.

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