Er, It's fantasy Chris. It doesn't have to represent reality
Fantasy of course, but since the artist dutifully distinguished between the keel (black) and the freeboard (brown), it's a pity that the cog appears to float like a cork. Heraldic depictions of medieval ships supposedly floating on water often fell into this error, probably because the heraldic artists of the time had no understanding of matters nautical. (The artist who put together this feast of heraldic whimsy does in fact know how to paint ships, so yes, it is deliberately fantastical.)