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 06 MAR 97
Subj:
INTERIM TECHNICAL GUIDANCE (ITG) - CVN DREDGE DEPTH CRITERIA
b. Reference (a) states further that, "shallower and/or narrow channels and/or higher speeds will require
greater allowance for squat." Since narrow channel widths and greater speeds result in greater ship sinkage
during transit (squat), and thus deeper water, planners should also include these effects.
c. Reference (a) also states that "port specific fouling clearance studies can be performed if requested
and funded" to possibly reduce the 6.0 foot fouling clearance criteria. The clearance criteria was derived from
condenser fouling studies on stationary ships berthed at NAVSTA Norfolk, VA in 1980. Locations that
exhibit more or less potential for fouling may require more or less clearance to prevent it.
d. Lastly, reference (a) states that "ship motions analyses of the remaining home ports and shipyards
will be completed...after receipt of funding." The motion analyses that NAVFAC prepared for Mayport and
San Diego predicted days of access and generated nomographs for other locations. For channels subjected to
significant waves, engineers and planners must evaluate these wave effects on ship motions.
Therefore, as noted in reference (a), facility engineers and planners should determine dredge depth
requirements by including the additional considerations of design water level, channel width and ship speed
impacts, dynamic effects of sea chest intake fouling, and wave effects. Additionally, they should include
effects from sedimentation and dredging tolerances.
Reference (b) designates responsibilities of the Chief of Naval Operations, Lead Activities, Shore Activities
having assigned water areas, Public Works Centers and Public Works Lead Activities, Naval Facilities
Engineering Command and Engineering Field Divisions, and Major Claimants regarding dredging
coordination.
3. Criteria: The cognizant activity should determine the dredge depth requirements as noted in reference
(b). Base these requirements on reference (a) including the effects of design water level, channel width, ship
speed, sea chest fouling, significant wave heights, sedimentation, and dredging tolerances according to
enclosure (1).
4.
Action:
a. Lead Activities and Shore Activities having assigned water areas determine dredge depth
requirements for Nimitz class aircraft carriers according to enclosure (1).
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