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Navigational Safety

Updated: Dec 21, 2021


American Pilots’ Association

It is in these off-shore, unsheltered, restricted channels – with the challenging combination of strong currents, confused winds, heavy vessel traffic, and close proximity to dangerous shoal waters – where pilots ply their trade. It is precisely in these port approaches, with vessel traffic funneled together, narrow offshore channels and sea lanes, shoal waters, and challenging winds and currents, where pilots must exercise their independent judgement.


The APA is using adverse conditions to justify non-compliance in non-adverse conditions. NOAA’s assessment does not suggest that the navigational safety provision should be weakened or eliminated, only that it should not be used as a justification for high transit speed in non-adverse conditions. Data in our analysis indicate a significant level of opportunity for compliant pilotage.

Data for transits at 10- knots or less indicate generally good navigational safety margins. Effective beam calculations based on AIS data from Charleston and Savannah indicate ships do not get swept into high yaw angles in average conditions. In Charleston’s and Savannah’s entrance channels the difference in yaw angles between compliant and non-compliant ships is less than 1 degree.

Regulatory language should be strengthened to allow pilots to use their independent judgement, with monitoring, reporting, verification and potential enforcement for non-compliance.

Charleston Branch Pilots’ Association

The report references a…2019 study at the Army Corps laboratory in Vicksburg Mississippi, in which pilots from this organization participated, comprised (of) 4 simulation runs in the Charleston entrance channel with the ship going 10 knots and winds of 30 knots. The objective of that simulation project was to evaluate newly designed channel improvements throughout the port and focused primarily on the harbor channels with 128 more runs, so the conclusions referenced are based on a project convened for another purpose.

Another study of navigation in the Charleston entrance channel by US Army Engineering Research and Development Center...for the National Marine Fisheries Service, Probabilistic Risk Assessment of Impact of Vessel Speed Restrictions on Navigational Safety Analysis of Charleston Entrance Channel in November 2014 concluded that the navigational precision a mariner could reasonably attain is substantially reduced at 10 knots compared to normal safe speeds.


The 2019 study was not convened for another purpose; it was part of a study convened for the purpose described. Its value with respect to the entrance channel is that it functions as one of the few points of reference for vessels traveling at compliant speeds, given the rarity of real-world data of actual vessels under pilotage transiting the channel at 10 knots. It also helps to establish a high-wind threshold value, and two-way traffic, as significant adverse conditions values.

The 2014 study does conclude that the navigational precision is substantially reduced at 10 knots compared to higher speeds. Whereas the 2019 study establishes a high threshold, this study describes a lower threshold. Together, they may constitute the basis for a general understanding of the range of adverse conditions.

Bridge simulations should be run to identify adverse and non-adverse wind thresholds and navigational safety provision guidelines. Operational decisions, like limiting traffic to one-way in actual adverse wind conditions, and pilots’ independent judgement, can be tested. Bridge simulations will help identify a range of non-adverse conditions, leading to appropriate management practices. In practice, questionable instances of non-compliance could be reviewed using ships logs, which should be available for timely review by the USCG and NOAA OLE.

Monitoring and enforceable standards should be established; ultimately, federal responsibility pertaining to entrance channels, which have not kept pace with shipping or port infrastructure, should be addressed. A closer reading of the National Economic Interest (NEI) references in the Army Corps of Engineers Post 45 report may be useful.

Please see: Marine Mammal Commission and Southern Environmental Law Center’s public comments.

Also: "Court Rejects Federal Attempt to Sink Right Whale Ship Strike Lawsuit"(WDC); see lawsuit brought by Center for Biological Diversity, Conservation Law Foundation, Whale and Dolphin Conservation and Defenders of Wildlife challenges the National Marine Fisheries Service’s delay in responding to rulemaking petitions on vessel strikes.

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