15 August 2002
Secure machinery with anchor bolts embedded in chamber foundations.
Provide watertight manholes for limited ready access to machinery, and
an overall pit cover made in sections to permit removal of machinery.
Provide capstan pits with drainage systems large enough to drain off
Capstan pits, subject to humidity that might interfere with electric motor
operation, may require portable blowers to dry out the pit before operation.
For drawing of capstan and pit for drydock application, refer to American
Civil Engineering Practice, Volume II.
Controls. Install electric power capstan controls in machinery pits.
Provide topside controls, and locate them so that they allow the operator an
unobstructed view, clear of lines and working parties. Topside controls should be
portable so they may be stowed when not in use. Install controls in watertight
Bollards. Bollards are cast steel, upright (concrete filled) posts secured
to foundations by steel bolts. Refer to MIL-HDBK-1025/1 Piers and Wharves for design
Location. Set bollards in line with the capstans at approximately 15.24 m
(50 ft) on centers between capstans.
Pull. Use bollards capable of withstanding a pull of 45,500 kg (100,000
Shape. Bollards must be shaped so that lines will not slip, jam, or ride off
Foundations. A bollard foundation may be a large block of concrete
adequately supported by piles arranged to resist large overturning moments.
Construction economy may be effected by tying bollard foundations to outer crane rail
Cleats. Install cleats (heavy cast steel fittings with horns) spaced about
60 ft (18.3 m) on centers on the coping, and use for securing mooring lines. Refer to
MIL-HDBK-1025/1piers and Wharves for design of cleats.
Stairways. Stairways in the drydock may be cast as part of the wall
concrete or may be constructed of structural steel with open mesh steel treads. Since
steel stairways can be damaged by falling objects, fouled lines, and swinging crane
loads, bolt the supports to the walls in order to facilitate repair. Install stairways at the
One from coping to floor on each side of the dock, inshore from inner