Tracing The ICW

By Bill Parlatore

It's the yellow brick road for thousands of boaters along the Intracoastal Waterway, but the ICW's magenta line is sorely in need of an update.

Photo of a Grand Banks 46 Classic tied up on the ICW in North CarolinaA Grand Banks 46 Classic tied up on the ICW in North Carolina. (Photo: North Carolina Tourism)

We begin on an unsettled day in May, apparently a bit too soon for summer's warmth, but late enough that most snowbirds have taken flight. It was clearing for the first time in a week, the break in relentless wind and driving rain raising our hopes that we might finally see some nice weather. It had been a wet, windy trip up from Florida, forcing us inside the ICW after offshore conditions made life lumpy, even on our supremely capable Grand Banks 46 trawler. She's a beautiful and rugged vessel, so crew comfort dictated our decision, rather than the ultimate safety of the boat. My shipmates were two retired professionals, both former Coast Guard officers, well-versed in things of the sea. No newbies.

We'd all hoped for a mostly offshore passage up the coast to Annapolis, a chance to travel in company with dolphins and sea turtles ever present at the 12-mile territorial boundary. But that plan was short-lived, and we diverted into the protected waters of the ICW at Florida's northern border. From there we'd follow the charted magenta line that showed the route along this inside waterway.

The ICW connects rivers, canals, sounds, and cuts into a continuous navigable waterway that stretches along the Atlantic and Gulf of Mexico coasts from New England to the Florida Keys and west to Texas. It offers commercial, military, and recreational mariners a mostly protected alternative to venturing offshore when conditions turn ugly. The ICW also happens to pass through some very beautiful areas of the United States.

Our trip had been mostly uneventful, though we did have to seek refuge when steady 30-plus-mph winds forced the closure of several swing bridges along the North Carolina waterway. That was a first for me, as was seeing how sheets of green water over the boat can get through a full enclosure to soak everything on the flybridge aboard a 46-foot trawler, on a protected waterway! Imagine that.

ICW travel is fairly straightforward. For the most part, a skipper just follows the marked magenta line on the chart, which is especially helpful when a boat exits a confined channel into a wide sound with no obvious direction to go next. The magenta line is also handy through a busy harbor or inlet, such as in St. Augustine, where it is easy to get confused. An early-morning departure found us motoring north on calm seas in the Alligator River, northbound to the Albemarle Sound. With any luck, we'd make Annapolis in a couple of days. We reached the Alligator River Swing Bridge midmorning, and I began to relax. The early departure meant we'd be across Albemarle Sound before the winds came up. Good plan.

Then a curious thing happened. Within moments of leaving the swing bridge behind, we were hard aground, stopped dead in our tracks. We then noticed we were in good company. A large sportfishing yacht lay a hundred yards out of the channel; it had been traveling fast when it ran out of water. This made no sense. We were more or less on the magenta line, and I'd been through this area dozens of times before, although not recently on a boat that drew four-and-a-half feet.

Our collective situational awareness had been on autopilot for days as we'd dutifully followed the magenta line. Now, after grounding, we took a closer look at the plotter and iPad and paper chart. What we saw only confused us more. The magenta line squirreled around buoys in a way that had us wondering if the rules of the road had suddenly switched directions. There was something wrong. We powered off the bottom at a snail's pace, still trying to figure out what had happened while looking for a way back into the main channel. We found our way out, thankfully, mostly by looking at the water, and were soon back on our way. We made it to Annapolis without additional drama, and, as if to either mock or celebrate our arrival, the bright sun finally came out as we passed the seawall of the U.S. Naval Academy, a reminder of the offshore passage that might have been. But that is boating, isn't it?

Our grounding experience still bothered me. Was the magenta line meant to be the yellow brick road by those who created and maintained it or not? I decided to find out more about how the magenta line comes to be, and what it means. I always assumed some all-knowing Ph.D. sat in a big comfy chair, surrounded by huge displays, spending each day updating chart information, massaging the magenta line to fit the curves and bends of current typography, using the latest technology and multi-quad core processing speed. I couldn't have been more wrong.

Photo of the author on his boat in the ICWDespite carefully following the magenta line, the author was surprised
to run aground in North Carolina.

Origins Of The ICW And The Magenta Line

With the help of BoatUS, I contacted the NOAA Office of Coast Survey (OCS), our nation's chief charting agency, and began a conversation with Communications Specialist Dawn Forsythe, who worked my questions through the staff of OCS cartographers. She confirmed that all U.S. nautical charts are the responsibility of the Office of Coast Survey, which maintains source data for all forms of paper and electronic charts. All charts found in chart kits, guidebooks, and electronic chartplotters originate from this agency.

The Atlantic and Gulf Coast Intracoastal Waterways were assembled piecemeal beginning before the turn of the last century but were not fully constituted with those names until 1939 in the case of the Atlantic, and 1949 for the Gulf. One of the larger milestones along that journey occurred with the passage of the River and Harbor Acts of 1902 and 1903 that authorized studies to join various sections of open water with privately constructed canals, and locally dredged channels supported by tolls, and publicly funded land cuts. At the time it was imperative to find continuous water routes for defense and commercial needs, as shipping along treacherous coastlines had serious risks.

The U.S. Coast and Geodetic Survey (USC&GS), a predecessor of NOAA, published its first edition of the Inside Route Pilot in 1912. Included were charts that showed protected routes inside the coasts from New York to Key West and from Key West to Texas. This publication met the needs of the motor-powered vessels that took advantage of increasingly modern navigation for commercial travel. The Inside Route Pilot included hand-drawn red lines highlighting routes on the charts. It was the precursor of what we now know as the magenta line. Interestingly, a controlling depth of just three feet was sufficient for the time. Six editions of the Inside Route Pilot were published between 1912 and 1935. The updates highlighted changes in lights and buoys, variations in typography, and new hazards to navigation. The red-line markings remained much the same over these 23 years.

Now, let's move forward to 1935, and America's struggle to get out of the Great Depression. Among the many government programs to stimulate the economy and get people working, the Public Works Administration more than tripled the USC&GS budget. These additional funds greatly increased the agency's ability to do its job, and one project it undertook was to modernize nautical charts. The agency doubled the number of workers available to conduct field surveys of the waterways. Noting the increasing demands of commercial traffic, they also changed the controlling depths to fit the draft requirements of this traffic. The surveys specified depths of no less than seven feet on the Atlantic waterway and no less than six feet out to Corpus Christi. The substantial investment in this project greatly improved the charts and the entire waterway system, which now stretched from New York to Texas. The new charts included updated magenta-line detail. In the years since, authorized depths have been modified and additional surveys have been conducted, but for the most part, the magenta line has not changed since 1936.

Where Does That Leave Us?

Surprisingly, the magenta line has not been "owned" by any federal agency for quite some time. It seems to have gotten lost among the other realities that define the national maritime landscape. Today the Atlantic and Gulf ICW systems are managed by the U.S. Army Corps of Engineers. NOAA Office of Coast Survey doesn't even survey the ICW, except when requested by the Corps of Engineers in special interagency instances, as in the case of post-Sandy storm damage assessment.

But that isn't to say the magenta line has been untouched. For some period of time, inaccurate portions of the magenta line were simply deleted. It was felt that nothing was worse than providing incorrect information, so it was better to remove these areas rather than keep them on a chart to mislead mariners. One might argue this made sense, but it was a short-term fix that ignored the grander vision of improving the overall system. In March, Commander Shepard Smith became the new chief of Coast Survey's Marine Chart Division. With his appointment comes opportunity. CDR Smith's office wants to review the current state of the magenta line, assign responsibility for it, and develop a plan to make it an accurate and safe navigation tool for all mariners. These efforts will likely involve the U.S. Power Squadrons, U.S. Coast Guard Auxiliary, perhaps even BoatUS His office expects to invite the boating community to participate.

The concept of a protected inland waterway along our coast is as valid today as it was a century ago. A national treasure, wondrously rich in history and natural beauty, the ICW still offers outstanding utility for commercial and recreational use, and is a lasting tribute to our nation's maritime heritage. As for the magenta line, good things are on the horizon for a navigation tool that hasn't had much attention in almost 80 years. Stay tuned. 

Bill and Laurene Parlatore founded PassageMaker magazine, and enjoy boating in many forms, including recent adventures on the French canals.

— Published: October/November 2013

Keeping Our Charts Accurate

The magenta line isn't the only line on our charts that requires updating. With 500,000 square nautical miles of navigable waters in our country, and 95,000 miles of shoreline, NOAA's Office of Coast Survey has an enormous job. These days, underwater mapping has become more complicated than ever, with rising water levels, shifting sediments, shoaling, and the increasing number of extreme storm events. All these changes significantly impact the underwater landscape, making NOAA's job more crucial than ever.

NOAA has four primary survey vessels — two on the East Coast, two on the West. Together with contract vessels, they survey approximately 3,000 square nautical miles of U.S. waters each year. In 2013, that number will be greater given the additional survey needs in the Northeast due to the altered shoreline from Superstorm Sandy. Data is collected and processed aboard the ship, around the clock, then sent to one of two processing facilities, in Norfolk, Virginia, and Seattle, Washington. In areas with rugged shorelines where survey vessels can't operate safely, aircraft determine near-shore water depths through bathymetric light-detection-and-ranging technology.

At the processing centers, staff sort through the millions of soundings to determine those most significant to cartographers. For example, if an area is 30 feet deep and then becomes 29 feet, 8 inches, does that need to be recorded on the chart? While a four-inch difference may not be that important to recreational boats, inches determine how much can be loaded onto a ship in a shipping channel and can have an enormous economic impact.

Data is then sent to the Marine Chart Division of NOAA in Silver Spring, Maryland, and transferred to paper, raster, and electronic nautical charts. In bygone days, data was hand-etched in reverse onto copper plates! Now it happens digitally. For paper charts, data is sent to the Federal Aviation Administration, which prints them. There are also print-on-demand charts, new booklet charts, and electronic navigation charts that are free for download or may be purchased through a provider. In all, it takes about a year from the ship survey to inclusion in NOAA's database of electronic charts. For urgent changes, such as a hazard to navigation, NOAA survey vessels submit "Danger to Navigation Reports" as soon as practicable after discovery and ahead of the complete survey package for incorporation into "Notice to Mariners." Every paper chart has an edition number and date (month and year of printing) in the lower left-hand corner. To see if NOAA has updated your chart, go to Dates of Latest Editions.

— Susan Shingledecker, BoatUS Foundation For Boating Safety & Clean Water; Member, NOAA Hydrographic Services Panel


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