Mount Stuart Graving Dock No.3

Mount Stuart Graving Dock No.3 is a dry dock that measures approximately 160 meters long and 25 meters wide. The sea walls of the dock are constructed from massive blocks of grey-brown stone, topped with granite copings. Some of the coping stones feature squat cast iron bollards, and there are rebates for gates and passages for machinery. The stepped walls of the dock are made of concrete.

The dock has a double set of sea gates. The outer gates are hollow metal with a railed wooden walkway above them; these gates open outwards into rebates in the sea wall and are operated by hydraulic rams. The lower inner gates open inwards, also using hydraulic rams located in passages behind the rebates. The outer end of the dock is raised above the main dock area, featuring a concrete floor with pits for hydraulic mechanisms that are covered by metal plating.

Each side of the entrance has a large powered capstan and a bollard approximately 60 meters high. Along the southwest side of the dock, about 6 meters from the dockside, there is a row of bollards and manual capstans. Additional bollards and capstans are located on the northeast side between Docks No. 3 and No. 2. Both sides of the dock have rails, or seating for rails, designed for travelling cranes or hoists. There are steps leading down into the dock, with one set at the sea end and two at the northwest end, featuring metal strings and wooden treads. Metal railings are present along the sides of the dock.