The rate hull maintenance technician has only existed in the United States Navy since 1972. Prior to that the rate was split into four different rates including plumber, shipfitter, metalsmith, and pipefitter. The history of these different rates is shown through the current rating badge. It consists of a maul; (consistent with the shipfitters and metalsmiths), an axe; (showing an in depth knowledge of firefighting and damage control), and the carpenters square; (which displays an ability to design as well as construct anything the ship may need).