I thought of a heraldic sea-eagle, (i.e., the upper portion an eagle, the lower, fish/whale-like) thus representing both air and sea, with the added advantage of the eagle portion of the charge symbolizing the United States of America.

Terry your crest is inspiring.  :D And I was in fact a green shirt, Aviation Boatswain’s Mate 3rd Class.  My rate badge is a pair of crossed anchors, one wing issuing from each of the outer stock arms.  I have a few images of that rolling around in my head now.  Oh, and just had the idea of a merman armed with a trident and shield.  The shield bearing the anchors and wings.  If that’s possible.  Also, two wings conjoined in lure with two crossed anchors overall.  That’s interesting.