The fore castles, poop decks and quarter decks (where you might expect to find a swivel gun of this type) of fighting galleons of this period were highly painted/decorated. As the figure would appear to be a senior officer he more than likely standing on the poop deck.
Suggest you do a Google images search on, say, the Golden Hind or Elizabethan galleons, for reference.
Personally I would paint the higher relief parts in red, black and yellow leaving the rest stained timber, just to add some colour.