All hail the coolship. It’s a shallow, open-top vat where wort-to-be-beer cools, collecting airborne bacteria and yeast that will ferment the beer spontaneously. It’s a vessel where powerful, unpredictable forces of nature take place, yielding complex beers with highly nuanced aromas and flavors.
Jeff Sparrow’s book Wild Brews (Brewers Publications, 2005) identifies the coolship as the most classic cooling method in brewing. “All breweries once had to use some form of a coolship,” Sparrow writes. “It is shallow to promote the greatest contact with the air to induce as rapid a cooling as possible. Windows or slats in the coolship room, open to the outdoors, allow the cool outside air to come into contact with the beer.”
The first coolship at Jester King Brewey in Austin, Texas, was a makeshift, miniature one. “The very first batch we brewed was a barrel-aged wild ale, inoculated with wild yeast isolated from local air using a miniature coolship,” says Co-owner and Brewer Ron Extract. “That is, a pan of wort left overnight on the roof of the brewery.”