could you use the current logos and the gray overalls? it would be cool
here is the badges of rank
http://www.navy.gov.au/general/ranks.html
and you could use the overalls like the one picture here
http://en.wikipedia.org/wiki/Sea_Patrol_(TV_series) in the picture frame at the top
the overalls are all grey and feature the sailors name above the left pocket and the word NAVy on the right pocket. it would be better if they wore overalls all of the time