Quantcast CVN Dredge Depths Interim Technical Guidance

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4 March 1997
1.  This guidance explains the determination of minimum dredge depth requirements for U.S. Navy nuclear-
powered aircraft carriers (Nimitz or CVN 68 Class). The requirements presented herein provide consistency and
reliability in the determination of acceptable dredge depths for channels and berths used by active Nimitz class
aircraft carriers. The NAVFAC Criteria Office will address reserve status condition of CVNs when required.
Deviation from this minimum criteria requires a waiver from the NAVFAC Criteria Office which will be
coordinated with cognizant Major Claimants, Naval Sea Systems Command, and Chief of Naval Operations.
2.  Ideally, engineers and planners should base ship channel designs on physical model testing, risk analysis, and
ship simulator analysis. However, time and funding constraints may prevent this process. In any event, the
requesting activity should determine the required dredge depths for Military Construction Projects. Dredge depth
requirements for Nimitz class aircraft carriers depend on the type of waterway to be dredged. Four categories exist
based on the magnitude of wave-induced and speed-induced ship movement:
a. Outer channels entrance channels or waterways subject to significant wave action, that is, wave energy
resulting in vertical ship motions greater than 0.5 feet under design conditions.
b. Inner channels interior protected channels or waterways subject to minimal wave action, that is, wave
energy resulting in vertical ship motions less than 0.5 feet under design conditions.
c. Berths water areas where ship velocity approaches zero, such as anchorages, slips, and pier and wharf
berths that are subject to minimal wave action under design conditions; generally includes turning basins
except as noted below.
d. Special berths defined as berths subject to significant wave action under design conditions.
The following definitions apply:
Datum the horizontal plane from which the dredge depth requirement is referred, normally the local
tidal datum of Mean Lower Low Water (MLLW).
b. Design depth the distance below the datum that must be maintained for safe navigation and berthing,
also called the advertised, nominal, or project depth.
This depth usually appears on Navigational Charts.
c. Contract depth the distance below the datum that is initially dredged by the contract and includes
advanced maintenance dredging requirements but not the dredging tolerance (allowable overdepth). Also
called the required depth, it is the depth noted on the DD-1391 Project Documentation and indicates the
minimum depth required under the dredging contract.
d. Permitted depth the distance below datum to the lowest depth authorized by the regulatory agencies and
normally includes the dredging tolerance (allowable overdepth). Planners and engineers should use this
depth to determine estimated dredging quantities.
4.  Determine required dredge depths using sound engineering practice. The design depth is determined by
summing the following parameters:
a. Minimum water depth requirement the minimum water depth that must be available for safe operation.
For existing locations, use COMNAVSEASYSCOM ltr 11460 Ser 03D3/242 dtd 3 Jan 95 (Attachment
(a)) implemented as follows for design water level, squat, ship motions, and underkeel clearances. For
locations not addressed in Attachment (a), contact the NAVFAC Criteria Office for assistance.


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