Evaluating the seaman (6)
I believe the answer is:
rating
I believe this is a double definition.
'evaluating' is the first definition.
(rating is a kind of evaluating)
'the seaman' is the second definition.
(British term for a naval enlisted man)
(Other definitions for rating that I've seen before include "Grading or ranking" , "Ordinary seaman" , "Grade or assessment" , "Non-commissioned sailor - classification" , "Seaman; class" .)