Image above, Lateral-Sliding Watertight Door - A drawing of a typical lateral-sliding watertight door of the era. While the design details differ somewhat from those on Titanic, the principle components are the same. Note the automatic sill cover which prevented dirt and debris generated by foot traffic from collecting in the lower track of the door. Scott Andrews collection.

   Collision bulkhead - The foremost watertight bulkhead was termed the “collision bulkhead.” It was fitted for the specific purpose of serving as an inner skin in the event the bow should be broken open in an end-on collision. Because of the relatively small volume of the peak compartment, the amount of water that could enter would have little effect on the vessel’s trim; in addition, due to the small area of this bulkhead, the bursting pressure it could be subjected to was small and, being narrow, it was naturally strong. However, the integrity of the bulkhead depended directly on the amount of damage sustained by the bow. To ensure the bulkhead’s efficiency, it was placed a distance from the stem about one twentieth of the vessel’s length . . . (continued)

   Vertical-sliding watertight doors - The vertical sliding watertight doors giving communication between the various compartments at the Tank Top level were arranged on the drop system. They were designed by Harland & Wolff, made of cast iron of heavy section and worked on the “geared” system. These doors were fitted in two distinct sizes, with the doors through WTBs D through J having a clear opening measuring 5'-6" high by 4'-0" wide, while the doors at WTB K and aft were narrower, having a clear opening of 5'-6" x 2'-9". The wider doors were employed throughout the boiler rooms to deal with the large numbers of men passing through these compartments during each change of watch, and also to permit the passage of wheel barrows . . . With the exception of the last 18 to 24 inches, the doors did not fall like a guillotine, but descended gradually, requiring 25 to 30 seconds to close. The heaviest of these doorplates weighed about 15 cwt. (1,680 lbs.). In order to prevent any possibility of a man being caught in the door as it descended, hydraulic cataract cylinders similar to a gun recoil cylinder were arranged so that the speed of the door’s descent was comparatively slow . . . (continued)

Image Upper-left caption. At left, the float is to the left of the door below a horizontal line which indicates the height of the as-yet-to-be-fitted stokehold deck plates above the Tank Top. The image at right shows more of the area above the door, including part of the two hydraulic cataracts which checked the speed of descent of the door.

Image Middle-left caption. At the left of the image, part of the starboard wing shaft can be seen, visible through an opening in the bulkhead which will soon be closed up around the shaft with bolted plates and and a watertight gland. Clearly visible to the right of the door are the solenoid (A), friction clutch (B), weighted bellcrank (C), and hand releasing lever (D), as well the rod and lever from the actuating float (E) located below the deck plates of the compartment. Below the clutch, the gears and shaft of the hand raising gear (F) may be seen, while above the clutch is the remote operating shaft leading to the bulkhead deck above (G). Also visible in this image are the lugs (H) on the door frame and the corresponding wedges (J) on the door plate.