UFC 4-150-06
12 December 2001
wave height. Each set of nomographs reflects the direction of the
significant wave relative to the direction of the CVN in transit; i.e.,
Following Seas are collinear with and in the same direction of ship
movement, Quartering Seas are those that approach the aft quarter of the
ship at 45 degrees, Beam Seas impact broadside to the ship, Bow Seas
are those that approach the forward quarter of the ship at 45 degrees, and
Head Seas are collinear with but opposite to the ship movement. The
wave height and period should be transformed to and through the channel
entrance using local wave data or Army Corps of Engineers reports
entitled, Wave Information Studies of U.S. Coastlines.
For outer channels, use Hs for periods greater than 10 seconds with a 6 days/month
recurrence interval. Exclude hurricane waves. Here is an example: Determine the
wave climatology using available data determine the significant wave height, direction,
and period. Transform waves into harbor based on shoaling, refraction, and diffraction,
etc. Then based on local traffic and regulations, assume an average ship speed
through channel; e.g. 14 knots. Using the calculated wave climatology, assumed ship
speed, and the charts in Appendix F, determine the predicted vertical ship motion for all
applicable directions. For inner channels and berths, use Hs = 0. For special cases,
use Hs for periods greater than 10 seconds with a 25 yr recurrence interval, unless
directed differently by the Activity. Include hurricane waves if the berth is expected to
be occupied during that extreme event.
Clearance distance from the lowest point on the vessel to the design
depth. For berths, turning basins, and inner channels, Appendix B
incorporates a 1.83 m (6 ft) clearance to prevent ingestion of benthic
biota. This clearance when combined with installed discharge diffusers
reduces the possibility of condenser fouling. Additional studies may
reduce the requirement and can be performed if funded. The planner
must collect all historical data available regarding fouling of condensers to
ascertain the extent of the problem. The NAVFAC Criteria Office is
available to assist in analyzing this data. Notwithstanding, at berths the
planner must ensure that a minimum of 0.6 m (2 ft) of clearance is
provided at Extreme Low Water. See Table 5-6 for other categories:
5-35
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