Airships are the primary means of travel and trade in this age. The seas being far too dangerous to continuously traverse mean the skies are the best bet. There is an unspoken rule however when it comes to airships “why destroy when you can board?” Destroying an airship is rarely beneficial for anyone involved. The dangerous nature of the sea makes recovery of goods nearly impossible, and the equipment on even an empty airship is almost always worth the risk to not simply blow them out of the sky with cannon.
Sky piracy is a rather common affair, and as such merchant vessels almost always have capable warriors on board to fight off attackers. Most human and dwarven cities have a standing bounty for pirates and their ships, preferably alive and intact.