One of the most difficult lessons learned around this time was that people could break their necks when they jumped more than 10 feet down into the water while wearing rigid cork life jackets that were not fitted tightly.
Checking the performance of a life jacket by conducting tests from a specific height remains a key piece of testing protocol today. This check is called a jump test or water entry from a height. Almost all current international standards have requirements for devices to be tested for entry into the water from heights ranging from 1 meter to 4.5 meters (about 15 feet). The height required depends on the environment the devices are designed to work in. Devices intended for offshore service need to pass a jump test of at least 3 meters, and then after the jump, the device needs to meet all tests for in-water performance.
