And, if you could see the starboard side of the starboard tail fin, then you'd see the crest for the 154th, designating a 154th gunboat carrying Huscarles Marines!![]()
Doubtful - double unit heraldry is historically VERY limited for marking vessels.
It's more common on ground units - US, it's Division or independent brigade as a patch, and Regiment or Bn on the dress uniform shoulder strap. (Sometimes Corps-level buttons associated with specific regiments.)
Aircraft, I've neer seen doubles... port & SB always match. (National rondels on the wings)