UFC 4-213-10
15 August 2002
CHAPTER 3
DETERMINATION OF GRAVING DOCK DIMENSIONS
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MINIMUM INSIDE DIMENSIONS. This chapter presents design criteria
on graving dock dimensions with particular reference to minimum inside length, width,
depth, and inside configuration. The minimum inside dimensions of a graving dock
depends on the classes of ships to be accommodated. However, the exact
configuration of the inside of the walls and the resulting shape of the inside cross
section will represent a compromise between several conflicting factors, the dominating
one being the structural type that is finally selected. For designation of drydock
features, see Figure 3-1.
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REPAIR AND SHIPBUILDING DRYDOCKS. This type of double function
drydock is the only type constructed in naval shipyards. Ships needing routine
maintenance and repair, or those coming into drydock in a damaged condition,
obviously require a deeper dock than ships under construction that are generally
removed to a fitting-out pier for completion. A damaged ship may have a severe list
and/or trim requiring additional drydock depth.
3-2.1
Basic Dimensions. Lay out drydock plans according to the applicable
type of ship as shown in Table 3-1. Guidance for dimensional allowances to ease ship
positioning and provide industrial space for shipbuilding or repair work are:
Keel block height (normal)
1.2 - 1.8 m (4-6 ft)
Clearance over blocks 0.6 m (2 ft)
Length clearances:
Head end
1.5 3.0 m (5-10 ft)
Outboard end
4.6 12.2 m (15-40 ft)
Width clearance each side
3.0 4.6 m (10-15 ft)
3-2.2
Relationship to Height of Blocking. The draft of a ship that can be
docked for any given depth from water level to drydock floor is associated with the
height of the blocking. For new docks, use 1.22 m (4 ft) minimal height of blocking,
giving consideration to higher blocking required for docking vessels with sonar domes.
3-2.3
Allowance for Sonar Domes. Sonar domes are ordinarily located on the
fore part of the ship keel. For a new dock to accommodate vessels so equipped, use
the height of blocking required for removing domes with a sonar dolly. Sonar equipment
is of various configurations and no set rules can be given (see Figure 3-2). Specific
criteria shall be outlined in project requirements. Sonar dome pits have been installed
in some drydocks to reduce the required height of blocks.
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