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'''Coolship''' (Anglicized version of the Dutch/Flemish ''koelschip'') is a type of fermentation vessel used in the production of beer. Traditionally, a ''coolship'' is a broad, open-top, flat vessel in which wort cools. The high surface to mass ratio allows for more efficient cooling. Contemporary usage includes any open fermentor used in the production of beer, even when using modern mechanical cooling techniques. Traditionally, ''coolships'' were constructed of wood, but later were lined with iron or copper for better thermal conductivity. See also the [http://www.milkthefunk.com/ccc/ MTF Coolship Cooling Calculator]. See [[Spontaneous_Fermentation#Cooling|Spontaneous Fermentation]] for information on dissolved oxygen in wort that is cooled overnight in a coolship.

Homebrewers may use coolships in their home brewhouse as a way to cool and inoculate beers to be spontaneously fermented. The purpose of a coolship for homebrewers is identical to commercial brewers. (This section in progressFor more information on the process of brewing with a coolship, see [[Spontaneous Fermentation]].) However, the vessel selected as a coolship generally will be determined by the available resources of the homebrewer and the effect of the coolship will be driven by the surface area to volume ratio of the wort within the coolship.

Many homebrewers will construct a miniature coolship, as seen by Devin Bell's picture. Devin has reported good results from using his miniature coolship <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1110677075627172/?comment_id=1110818382279708&offset=0&total_comments=7&comment_trackingCommon Homebrew Coolships===%7B%22tn%22%3A%22R4%22%7D Conversation Homebrew coolships range from repurposed vessels to custom designed equipment. There are costs and benefits associated with Devil Bell on the results of using his coolship. 7/16/2015.]</ref>. The benefit of building one is each design that a ball valve can should be installed near the bottom of the coolship, which will make transferring the wort easier. Another option that some people have reported trying is purchasing a large stainless steel pans from a restaurant supply store, as well as food grade plastic traysconsidered.

The third option is Some homebrewers prefer to use your boil kettle. At purchase or repurpose from the 2015 National Homebrewer's Conference home suitable shallow, food grade containers used in San Diegocooking or catering. These include stainless steel or aluminum baking pans, James Howat's presentationlarge glass baking pans, ''Wild food grade plastic trays and Spontaneous Fermentation at Home'', brought up the issue of [https://en.wikipedia.org/wiki/Surface-area-to-volume_ratio surface area to volume ratio] <ref name="Howat">[http://www.homebrewersassociationstorage containers.org/how-to-brew/resources/conference-seminars/ ''Wild These vessels are often cheap and Spontaneous Fermentation at Home''may already be available in the home. Presentation by James Howat at 2015 NHC.]</ref>. The ''surface area It can be tough working with large vessels with no valve to volume ratio'' of drain the coolship into a fermentor. One must make sure the selected vessel is designed for use with hot liquid, directly affects the cooling rate of that liquid (liquids so it affects the cooling rate of all objects, does not just liquids) <ref>[http://wwwcrack or melt.fmf.uni-lj.si/~planinsic/articles/Cheese%20cubes_EJP.pdf The surface-to-volume ratio Cooling boiling wort in thermal physics: plastic containers that are not rated for boiling temperatures may leech chemicals from cheese cube physics to animal metabolism. Gorazd Planinsic and Michael Vollmer. European Journal of Physics. 29 (2008) 369–384.]</ref>. In other words, the greater the surface area of a given volume of liquidplastic depending on what they contain, the faster it cools. For example, imagine 100 liters of hot liquid is in a very wide and flat container. It will cool much faster than if it was in a perfectly square container, and even faster still than if it was in a spherical container. See [http://wordpress.mrreid.org/2011/10/20/spherical-ice-cubes-and-surface-area-to-volume-ratio/ this article for another explanation of how surface area to volume ratio affects cooling]they are food grade.

Others design coolships using specialized equipment fabricated for that purpose or created out of stainless steel or copper parts. An easy route to design a coolship may employ restaurant supplies such as steel storage racks and stainless steel tubs. These designs allow for convenient features such as a ball valve for draining the cooled wort or screening to keep out break material from the boil kettle. The coolship can be built to an optimum surface area to volume ratio. These coolships are often the most expensive route but the most customized and durable. A third option is to use the boil kettle as a coolship. In this method the kettle is simply left outside after the boil. Here there is no need to purchase or design a separate vessel and it may already provide a valve to drain the cooled wort and handles for easy movement. However, by using the boil kettle the brewer has no choice in the surface area to volume ratio of the cooling wort and there is no opportunity to remove the break material from the wort prior to cooling. Regardless of the method selected, the surface area to volume ratio should be carefully considered due to its affects on cooling and microorganism populations in the spontaneous fermentation. ===Surface Area to Volume Ratio Example===James HowatAbbreviated '''SA:V'''s example , the surface area to volume ratio is the proportion between the surface area of the wort (the dimensions of the wort exposed to the sides of the vessel), and the volume of the wort. The SA:V affects the cooling rate of how the wort. In addition to find this, the surface area of the top of the vessel which is exposed to air in proportion to the volume ratio of wort potentially affects the inoculation rate of the vessel.  ====Cooling Rate====The cooling rate of the exposed wort is influenced by a number of factors including the ambient temperature, the [https://en.wikipedia.org/wiki/Thermal_conductivity thermal conductivity] of the coolship material (for example, Jester King Brewery noted a faster, more preferable cooling rate for a 30 bbl coolship made from copper versus stainless steel because copper is found belowa better thermal conductor <ref>[http://www.thebrewingnetwork.com/session-jester-king-brewery/ "Jester King Brewery"; Interview with Averie Swanson from Jester King Brewery. Brewing Network Session Podcast. 01/30/2017. Note that this example is not a true ~1:22:00 minutes in.]</ref>), and the surface area to volume ratio equation<ref>[http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/heatingandcooling/heatingrev6.shtml ''Energy transfer by heating''. BBC website, Bitesize section. Retrieved 7/24/2015.]</ref>. The most important factor is the ambient temperature, but the easiest variable to control is the surface area to volume ratio. The greater the surface area of a simplified version that only measures given liquid the top faster it will cool <ref>[http://www.fmf.uni-lj.si/~planinsic/articles/Cheese%20cubes_EJP.pdf The surface-to-volume ratio in thermal physics: from cheese cube physics to animal metabolism. Gorazd Planinsic and Michael Vollmer. European Journal of Physics. 29 (2008) 369–384.]</ref>. For example, imagine 100 liters of hot liquid is in a very wide and flat container. It will cool much faster than if it was in a perfectly square container, and even faster still than if it was in a spherical container. See [http://wordpress.mrreid.org/2011/10/20/spherical-ice-cubes-and-surface -area-to-volume-ratio/ this article for another explanation of how surface area to volume ratio affects cooling].The more surface area to volume ratio, the more microorganisms that will be collected in the coolshipfor the given volume of wort <ref name="Howat">[http://www.homebrewersassociation.org/how-to-brew/resources/conference-seminars/ ''Wild and Spontaneous Fermentation at Home''. It makes sense Presentation by James Howat at 2015 NHC.]</ref>.  Some brewers claim that controlling the speed of cooling is important to only consider assembling a desired blend of microorganisms in the top wort <ref name="Howat"></ref>. Microbes survive and multiply at different temperatures and cooling too long or too fast may produce a beer that lacks desirable character or possesses an excess of undesirable character. A larger surface area of wort will allow for greater inoculation of microbes although if the wort cools too quickly the majority of inoculation will occur at cooler temperatures and affect the ratio and growth of various microbes in the wort. (For more information on the coolship since most effects of the heat cooling rate see [[Spontaneous Fermentation]].) Scaling a commercial-sized coolship down to homebrewing volumes will escape from produce a coolship that does not match the uncovered top surface area to volume ratio of the larger coolship. A true For this reason, the surface area to volume ratio would show an even larger difference should be the driving factor in determining how to design the shape and depth of a homebrewing coolship. In his 2015 National Homebrewer's Conference presentation, Wild and Spontaneous Fermentation at Home, James Howat provides a comparison of the surface area to volume ratios between a 36 BBL coolship and a 10 gallon coolship scaled down linearly from the two example coolships below 36 BBL coolship <ref name="Howat"></ref>.

::Dimensions of the example 36 coolship: 10 ft ' x 10 ft ' x 1.5 ft'.

::Surface area of the top surface of the wort (2wl + 2lh + 2wh) = 100 square feet260 sq. ft.::Surface Area to Volume ratio = 100260/150 = '''01.6773''' square feet sq. ft. per cubic foot.

::Dimensions of the example miniature 10 gallon coolship: 2.5 ft ' x 2.5 ft ' x 0.20 ft (2.4 inches).'

::Surface area of the top surface of the wort (2wl + 2lh + 2wh) = 614.5 sq.25 square feetft.::Surface Area to Volume ratio = 614.255/1.25 = '''511.6''' square feet sq. ft. per cubic foot.

The above This example shows that the surface area to volume indicates a substantially lower ratio of for the 36 bbl BBL coolship is much less than . At the lower ratio, the wort will cool considerably slower. As a result difference in cooling rate between the two coolships, the surface area inoculation rate and ratio between microorganisms will differ. Designing a coolship for homebrew volumes may result in a coolship that does not appear similar to its larger companions. To get as close to volume the 1.73 ratio of the 36 BBL coolship with our 10 gallon coolshipexample, thus it will cool slowerthe dimensions would have to be as close to a cube as possible with dimensions approximately 1.1' x 1.1' x 1.03'. This still only gives a SA:V of 4.9 sq. ft. per cubic foot. A homebrewer desiring a more shallow vessel may insulate the coolship to slow the cooling rate although this may affect the inoculate rate. A typical homebrew-volume boil kettle (math not provided due to it involving circles) has dimensions that provide a surface area to volume ratio that is closer to the 36 bbl larger coolship (estimated 1-2 square feet sq. ft. per cubic foot). Further insulation of and insulating the boil kettle when using it as a coolship may help obtain a slow the cooling rate closer to that is comparable of a commercial-volume coolship. ====Inoculation Surface Area====The ''top'' surface area to volume ratio affects the inoculation rate. Some brewers may want their coolship inoculation rate to be somewhere near what commercial coolships are. An example to find the SA:V ratio of just the top surface using the same two coolship dimensions follows: <code>:Example of a 36 bbl coolship:::Dimensions of the 36 coolship: 10' x 10' x 1.5'.::Wort volume = 1122 gallons = 150 cubic feet. Other factors that influence ::Surface area of the cooling rate top surface of the wort are (w x l) = 100 sq. ft.::Surface Area to Volume ratio = 100/150 = '''0.67''' sq. ft. per cubic foot :Example of a 10 gallon coolship:::Dimensions of the 10 gallon coolship: 2.5' x 2.5' x 0.20'::Wort volume: 9.35 gallons = 1.25 cubic feet.::Surface area of the temperature between top surface of the wort and its surroundings(w x l) = 6.25 sq. ft.::Surface Area to Volume ratio = 6.25/1.25 = '''5''' sq. ft. per cubic foot</code>  The example above shows that the shallow 10 gallon coolship also has a much larger ''top'' surface area to volume ratio. ====Coolship SA:V Calculator==== Mark B. Fry's coolship SA:V calculator will calculate the SA:V for cylindrical kettles (updated by Joe Idoni to include a second tab for rectangular coolships). In order to use the files they must be downloaded. Click "File", "Download as", and what the select "Microsoft Excel (.xlsx)":* [https://endocs.wikipediagoogle.orgcom/wikispreadsheets/d/1HFBTCt99OQ9-jSGI9jBZXwC6SqtZZVwlpXYw2rjLO4k/Thermal_conductivity thermal conductivityedit#gid=90184859 Original spreadsheet by Mark B. Fry (download and save a copy to use).] is of the material that the coolship is made out of* [https://docs.google.com/spreadsheets/d/1gB4347cP70Sw6topMoOvDydMYQcS2PF7M0Yl0vgbZbk/edit#gid=1777054704 Updated version by Joe Idoni with tab for rectangular coolships (second tab; download and save a copy to use).]

Another factor that is affected by the surface area to volume ratio is the inoculation rate==Commercial Coolships=====Manufacturers===Any metal tank manufacturer can generally build a coolship <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1327576813937196/?comment_id=1327588103936067&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Conversation with Joe Wells on MTF. The larger the surface area, the more microbes that are collected06/11/2016.]</ref>. However, it has been shown below are manufacturers that the surface area to volume ratio of large commercial coolships is adequate for collecting microbes, so specialize in theory this shouldn't be a concern their construction for homebrewers <ref name="Howat"><commercial breweries: * [http://www.foedercrafters.com/koelschip/ref>Foedercrafters. For more information on the process of brewing with a coolship, see ]* [http://www.metalcraftfabrication.com/ Metal Crafters Fabrication.]* [Spontaneous Fermentationhttp://nsibrew.com Newlands (copper coolship).]].

Some commercial brewers have reported positive results from using industrial maple syrup boil pans. [https:''Editor's note: a discussion on the merits of cooling rates //www.facebook.com/groups/MilkTheFunk/permalink/1459172714110938/?comment_id=1459763314051878&comment_tracking=%7B%22tn%22%3A%22R2%22%7D See this MTF thread] for coolships is worthy of a separate, in-depth analysis, and currently isn't covered heremore information.''