Geiger Engineers performed the preliminary concept design of a retractable roof that would allow work in a covered environment at Electric Boat's Graving Dock 2 submarine dry-dock on the Thames River, Groton, CT. The dock has a plan area nominally 94 feet wide by 578 feet long. The retractable roof system is designed to uncover any one-third of the facility to allow for overhead crane access to place components in and remove components from the dry-dock. The twelve retractable arch roof panels are moved with cable winches mounted under concrete girders. One-third of the retractable roof covering can open in nominally 30 minutes, with a travel speed of 5 ft/min.