Public shipyards, which are owned and operated by the Navy, conduct a large majority of all submarine maintenance. To reduce delays at public shipyards, the Navy sent 29 submarines to private shipyards for Docking Selected Restricted Availability (DSRA) overhauls between 1993 and 2017. During that period, 117 DSRA overhauls were done at public shipyards. The overhauls conducted at private shipyards have been 31 percent less expensive, on average, by CBO’s estimate. That gap has narrowed in recent years, but CBO’s data include only one overhaul at a private shipyard after 2010.