A coolship: science-fact, not science-fiction
To the uninitiated, the word ‘coolship’ — an anglicisation of the Dutch ‘koelschip’ — may be seen in one’s mind’s eye as a seagoing vessel transporting ice, a leisurely vehicle for transporting Happy Days’ Arthur Fonzarelli, or something generically CGI and sci-fi from the silver screen. Each conjured-up image is far from reality, however, since a coolship is a well-established vessel used in the art of brewing for many hundreds of years.
Why a “cool ship”? In a bygone age the coolship may either have been developed from a waterborne vessel, or at least resembled a boat or watery craft of some kind — hence a ‘shipؙ’ — and cooling hot liquid is its function. It is, therefore, historically known as a cooling- or cool-ship.
Anybody familiar with brewing knows that wort — essentially a mix of hot water and powdered malt — needs to be rapidly cooled after boiling to minimise the risk of off-flavours developing in the finished beer (dimethyl sulphide, or ‘DMS’). The device used for cooling in most modern breweries is the ubiquitous heat exchanger, an apparatus that has many other non-beer applications and uses in the fields of domestic goods, air travel and energy production, for example.
Before the advent of the heat exchanger, hot things had to cool down naturally at their own pace. One way to cool a hot liquid is to increase its surface area, exposing a larger percentage of the liquid to the cooler air surrounding it so that heat is radiated away from the surface of the liquid.
This was achieved several hundred years ago in Belgian breweries by means of large, flat vessels that resemble shallow, open water-tanks, usually constructed of metal: the coolship.
The coolship is largely outdated, although it has always been used by Belgian breweries, specifically around Brussels, where they play a vital role in the production of lambic beer. However, there is a resurgence of historic technology and processes in the brewing world, fuelled not only by a desire to embrace something nostalgic because it’s hip and fashionable, but also because there is a realisation that the finished product often benefits from an enhanced taste, aroma or mouthfeel by re-establishing the methods of yesteryear.
The coolship faces a bright future as a highly desirable component in a brewery’s arsenal, with many breweries in the USA, for example, installing their own coolship. Often, the coolship is a bespoke piece of equipment, custom-built for the brewing team.
Kaeru Beer visited the Dovetail Brewery in Chicago to witness their custom-built coolship in action, and here are some short video snippets.