The tubing is sewn into the shirt to maximize cooling over a large surface area of the body, except it only works if cold water is running through the tubes. Once the water becomes body temperature, it is useless.

Racing equals heat. Anyone who has driven in a race can tell you how hot things get inside a racecar. I’m not just talking about engine or brake temperatures. I mean life is extremely hot for the driver. On a 90-degree day, wrapped from head to toe in Nomex, drivers can lose up to 5 pounds just from sweating it out as they work their magic behind the steering wheel.

There are a few different systems teams use to try to keep a driver’s body temperature down, such as the F.A.S.T. water-cooled suit system or the Cool Shirt water-cooled shirts. Both these systems are simple in design, using surgical tubing sewn into a shirt, with the tubing routed along the driver’s body and connected to what is essentially a beer cooler filled with water and ice. Cold water stored inside the cooler is circulated by a small water pump, which moves it from inside the cooler to the shirt tubing around the driver. These systems work great, and as soon as you flip the switch to the pump on, you can instantly feel cold water running around your body. The only drawback to the system is thermodynamics. Heat from the driver’s body is transferred to the water, which eventually melts the ice inside the cooler. Eventually all of the water becomes the same temperature as the driver’s body, and at that point the system is just pointless extra weight in the car. During a 100-degree day you can get about two and half hours of real cooling before the water becomes essentially urine temperature.

Two and a half hours of cooling doesn’t do anyone much good in a six-hour enduro. It certainly doesn’t help the anchor driver, who gets tossed in the car last to bring it home for the team. Because the ice inside the cooler melts and turns to water, you can’t add more ice to the system without overfilling the cooler, thus splashing a gallon of water into the interior of the racecar during a pit stop. Our team came up with a great solution to this problem, and we have been able to get a cool suit system to cool our drivers for not only 6 hours, but 24 hours straight. A simple wet/dry vacuum used during a pit stop to evacuate the water out of the cooler box allows room for more ice to be added into the box, thus providing cooling capacity for the next driver.

Having the cool suit box in the passenger foot well helps with crew member access during a pit stop. From this position, it is easy to vacuum out the warm water and refill with ice during an endurance racing pit stop.
Having the cool suit box in the passenger foot well helps with crew member access during a pit stop. From this position, it is easy to vacuum out the warm water and refill with ice during an endurance racing pit stop.
This is what the cooler looks like after three hours of racing, just a box full of warm water. The trick is to evacuate that water to make room for new ice, to help your next driver keep cool.
This is what the cooler looks like after three hours of racing, just a box full of warm water. The trick is to evacuate that water to make room for new ice, to help your next driver keep cool.

The process is simple. The car comes into the pit for fuel and a driver change. Once fueling is complete and work can be done on the car, a crew member pops the top off the cooler, inserts the vacuum hose into the cooler and sucks all but about 2 inches of water from the box (the system still needs some water to circulate). Then the crew member drops a large block of ice into the cooler box, shuts the lid, and the car is ready for action. With practice, this exchange can be done in the same amount of time it takes to strap in a driver or change a tire. No pit lane time is extended and the ability to keep the next driver cool is in place so he or she can stay focused for the job at hand, winning the race!

We used a Sharpie to mark the “minimum” line inside the box so crew members know when to stop drawing water out. A small amount of water is still needed in the system so it can be cooled by the fresh ice and circulate sweet coldness around the driver.
We used a Sharpie to mark the “minimum” line inside the box so crew members know when to stop drawing water out. A small amount of water is still needed in the system so it can be cooled by the fresh ice and circulate sweet coldness around the driver.
Any shape of ice will work, just fill it to the rim. We have found through testing that a large block of ice, shaped to fit exactly inside the cooler seems to last longer than the crushed ice shown in this photograph.
Any shape of ice will work, just fill it to the rim. We have found through testing that a large block of ice, shaped to fit exactly inside the cooler seems to last longer than the crushed ice shown in this photograph.
Here you can see the shop vacuum, a cooler with ice stored in it, and a generator all at the ready as a crew member slides in “duke boy style” through the passenger window to access the driver’s cooling system. Another crew member will assist by passing the vacuum hose, fresh ice, and towels just in case anything spills. Remember to empty the vacuum after each pit stop, because the water can fill the vacuum to its capacity quickly.
Here you can see the shop vacuum, a cooler with ice stored in it, and a generator all at the ready as a crew member slides in “duke boy style” through the passenger window to access the driver’s cooling system. Another crew member will assist by passing the vacuum hose, fresh ice, and towels just in case anything spills. Remember to empty the vacuum after each pit stop, because the water can fill the vacuum to its capacity quickly.
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Image courtesy of Rob Krider