From back of box:
Enhance your Space:1889 adventures with Cloudships and Gunboats: Detailed deck plans, construction rules, and standup adventurers help you resolve any negotiation, battle, or encounter within the Space 1889 role-playing system.
This expansion was intended to bridge the gap between the boardgame Sky Galleons of Mars and the role-playing game Space 1889. Ship to ship battles can be fought and won; but if there is an opportunity for a Boarding Actions, which were abstracted in Sky Galleons, they are now fleshed out in man-to-man, or man-to-Martian action. This allows for players to add characters from the role-playing game.
Weapons are added, and clarified from Sky Galleons. Shipwright's Handbook with data on the aerial navies of Earth and a ship record forms book. Rules for designing your own aerial vessels are included.