Wind-sails, aka Sails
Wind-sails are the traditional canvas sails used before Steam Engines—which are normally used as the secondary propulsion system.  Few Airships utilized Wind-sails anymore. Crystal technology and Etheric Engineering are what is currently used in propelling ships.
Most airships that favored sails were those from Fleets of poor Spires. Or—by scoundrels like pirates, smugglers and so on—those who were willing to to "dare the dangers of the mists rather than sail in open skies".
Grimm ordered the Sails readied, but kept reeled for now as they prepared to attack an Auroran airship. Bridget Tagwynn observes all of the Airship parts on the AMS Predator and considers the reasons why a ship might have sails.
- It was funny, Grimm mused, how often in life a bit of judicious silence could come in handy. — Grimm considering the advantages of wind-sails over Steam Engines.