Compliance and Ship Speed -- 2021-2022 SMA Season
CHARLESTON, SOUTH CAROLINA
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MANDATORY VESSEL SPEED RESTRICTION IN EFFECT
10 knot speed limit (November 1 - April 30)
This interactive map shows Panamax and Post-Panamax vessels at their maximum speeds for the last seven days. Hover to view details. The monitored section of the entrance channel is 9.7 nautical miles.
Ship Behavior at Charleston
Monitoring shows that in ordinary conditions ships appear to have ample margins for safety—the Charleston entrance channel can be navigated without risk at the regulatory 10 knot speed most of the time. See below.
Figures
Showing Last Seven Days (Updated Daily)
Speed distribution for Post-Panamax and Panamax vessels. 10 knot seasonal speed limit marked in red. Mean vessel speed (VSPD) is computed on a rolling seven-day basis. Automatic Identification System (AIS) data is recorded in one-minute time resolution for all vessel positions in the channel. Pan, zoom, hover for details.
Speed distribution for each monitored vessel. Ship speed is consistently high along the length of the channel. 10 knot mandatory speed limit marked in red. Hover to see details for each vessel, toggle the legend to isolate one-way or two-way traffic. Shown in one-minute time resolution on a rolling seven-day basis.
Wind speed (WSPD) Charleston SMA. NOAA data matched to AIS data in one-minute time resolution. Adverse WSPD Threshold of 30 mph identified by the U.S. Army Corps of Engineers and Charleston Pilots Association. See Charleston, South Carolina Navigation Study. Wind data based on weather buoys on a rolling seven-day basis. Pan, zoom, hover for details. NOAA buoy source.
VSPD vs WSPD. High vessel speed during non-adverse wind conditions. Legend showing vessel positions in one-minute time resolution. Wind data based on weather buoys on a rolling seven-day basis. 10 knot mandatory speed limit marked in red. Pan, zoom, hover for details.
Vessel yaw (course minus heading). Generally below 5º and rarely reaches the threshold for navigational safety indicated by the Charleston pilots of 10º. See Navigation Update: Charleston Branch Pilots Association. Vessel speed has negligible effect on yaw. VSPD-Yaw correlation is computed on a rolling seven-day basis, in one-minute time resolution for all positions in the channel. 10 knot mandatory speed limit and 10º yaw navigational safety threshold marked in red. Pan, zoom, hover for details.
Percent of Channel Occupied. The amount of leeway each vessel has in channel does not appear to be reliant on speed. 10 knot speed limit marked in red. Hover to see details for each vessel; toggle the legend to isolate one-way or two-way traffic. Shown in one-minute time resolution for all vessel positions in the channel on a rolling seven-day basis.