Thursday, September 26, 2013

Intracoastal Waterway Route “Magenta Line” on NOAA Nautical Charts

 See more information on the history of the Intracoastal Waterway Route

From Federal Register from Rear Admiral Gerd Glang (Director, Office of Coast Survey, National Ocean Service, National Oceanic and Atmospheric Administration)

Since 1912, a series of nautical charts of the Intracoastal Waterways, produced by the U.S. Coast and Geodetic Survey and, subsequently, NOAA, have depicted an Intracoastal Waterway Route, a “recommended route” known to recreational boaters and commercial mariners as “the magenta line.”
Coast Survey originally added the line to the charts to show the best route through the Intracoastal Waterway but it has not been consistently maintained since its last comprehensive update in 1936.
Aware of safety concerns, NOAA's Office of Coast Survey is removing the “recommended route” from NOAA nautical charts.

In 1938, Chart 830 explained the route depiction.

We are also issuing a Local Notice to Mariners, advising caution in using the line in charts where it has not been removed.
The Office of Coast Survey invites written comments about whether NOAA nautical charts should depict a recommended route through the Intracoastal Waterways.

 Intracoastal waterway in Miami
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The first known appearance of what is commonly referred to as the “magenta line” is in a set of eight charts (each titled “U.S. Coast and Geodetic Survey INSIDE ROUTE”) included in a now-defunct U.S. Coast & Geodetic Survey publication, Inside Route Pilot, 1st edition 1912.

As a sample, the chart edition from 1913
NOAA Historical Maps & Charts Collection

The U.S. Coast & Geodetic Survey published seven editions through 1935, when their depiction of the Intracoastal Waterway Route underwent a major update.
As the agency pointed out in their 1935 annual report, “the existing [pre-1935] charts of this system of waterways have been based principally on surveys made from 60 to 80 years ago and, necessarily, are obsolete in many respects.”

The U.S. Coast and Geodetic Survey received substantially more appropriations from the Public Works Administration in 1935, which allowed the agency to update the Intracoastal Waterways Route on nautical charts.
“[W]hile the entire area has not been surveyed, by concentrating on the through route and its most important tributaries, sufficient field surveys have been made so the charts of the entire route can be produced,” the agency director reported.
At some point, the Inside Route Pilot was discontinued (the latest edition in the NOAA Central Library is from 1936) and USC&GS changed its charting system.
Beginning in 1936, the “Inside Route” series of charts were absorbed into the Intracoastal Waterway nautical charts.
From 1936 to the present, the Intracoastal Waterway Route has remained on Intracoastal Waterway charts, largely without changes or updates.

Chart 830, from 1938, shows the magenta line after it was updated by thousands of field workers hired with funds from the Great Depression era's massive Public Works program. 

Current Status of the Intracoastal Waterway Route on Nautical Charts

 courtesy of Water Way Guide

Numerous examples can be found where the charted Intracoastal Waterway Route (“magenta line”) passes on the wrong side of aids to navigation; crosses shoals, obstructions, shoreline; and falls outside of dredged channels, etc.
Coast Survey is taking several actions to address the problems.
First, Coast Survey is systematically removing the Intracoastal Waterway Route “magenta line” from new editions of affected nautical charts.
Second, Coast Survey is preparing chart notes for dozens of charts that are updated but not issued as new editions, and where the magenta line will not be deleted.
Coast Survey will revise the chart notes and publish the revised notes in the Local Notice to Mariners. The LNMs will warn: “The general location of the Waterway is indicated by a magenta line. Mariners are advised to follow the aids to navigation and avoid charted shoals and obstructions.”
Third, Coast Survey is updating the position of the magenta line on current charts (not scheduled for new editions) when authoritative reports or information indicate proper re-positioning.Show citation box
Fourth, Coast Survey is considering the options for future charts: should NOAA continue to depict the “magenta line,” and what should the “magenta line” designate?

The Thin Magenta Line (book from Evelyn Chisolm and Robert de Gast)

Public Comments

The director of NOAA's Office of Coast Survey invites interested parties to submit comments to assist Coast Survey as it decides whether to maintain a new or updated magenta line depicting an Intracoastal Waterway Route on Intracoastal Waterway nautical charts.
Comments may address whether recreational or commercial mariners need a magenta line depicting a specified Intracoastal Waterway Route, and whether that should be a federal government charting responsibility. Additionally, the director specifically seeks comments regarding:
  1. How do you currently access the magenta line? On paper nautical charts, raster navigational charts, electronic navigational charts, commercial paper chart books, commercial charts, or other?
  2. How do you use the “magenta line”? Do you consider it to be a general route, a specific trackline, or a reference line?
  3. Given limited government resources, what are your ideas for how NOAA should develop and maintain a reinstated magenta line?
  4. How do you use the Intracoastal Waterway? Recreationally or commercially? Locally or long distance?
  5. What are your boat's length and draft?
Written, faxed, or emailed comments are due by midnight, December 26, 2013.

Email comments to, or fax to 301-713-4019.
Written comments may also be mailed to Lt.j.g. Leslie Flowers,
Office of Coast Survey, 1315 East-West Highway, #6312, Silver Spring MD 20906.
T : 301-713-2730, ext. 115
E :

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