Crossword Genius

Ancient oared vessel heard by military engineers (6)

Ross

I believe the answer is:

bireme

I'm a little stuck... Click here to teach me more about this clue!

'ancient oared vessel' is the definition.
'bireme' can be an answer for 'vessel' (I have seen 'Ancient vessel' mean 'bireme' so perhaps 'vessel' could also mean 'bireme'). I am unsure of the 'ancient oared' bit.

'heard by military engineers' is the wordplay.
'heard by' becomes 'bi' (I can't justify this - if you can you should believe this answer much more).
'military engineers' becomes 'REME' (Royal Electrical and Mechanical Engineers).
'bi'+'reme'='BIREME'

Can you help me to learn more?

(Other definitions for bireme that I've seen before include "old vessel?" , "with two tiers" , "rowing boat" , "Ancient vessel" , "Ancient oared warship" .)

I've seen this clue in The Times.
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