Reading the Shifting Sands (etc) of the ICW

By Kimball Livingston Posted March 19, 2014

With snowbirds counting the weeks until their migration north along the IntraCoastal Waterway—assuming this winter really does have an end—their transit of the ICW will include all the challenges of navigating shallow waters and shifting features. But with new sources of help from technology.

It’s very 2014, incorporating crowdsourced data generated by the users of Navionics electronic cartography products for chartplotters and mobile devices. The result: daily updates for near-real time news you can use. The benefits are obvious along a route notorious for its changeability. Or, as Navionics’ Shaun Ruge pegs it, a route fraught with “soon-to-be-suspect data, as in anything that was true yesterday along the ICW.”

NOAA’s traditional magenta line, marking the suggested channels, is becoming a lot less important. At one point last fall, NOAA announced that it was going to drop the magenta line altogether. Now it speaks of improving the performance of the magenta line. But there’s a but.

Navionics, ahead of NOAA’s announcements, had begun developing a framework for a two-part updating process in which their users’ opt-in shared information plus data from their aggregated under-way sonar logs (recorded through the company web site) can be used to crowdsource exactly the sort of information that matters in the moment, on the water. Quoting from Navionics, ICW data will include: “Up-to-date commanding depths, vertical and horizontal bridge clearances, accurate speed limits, vertical overhead cable clearance, updated coastlines, freshest-data bottom contours and suggested routes.”

Simply put, there is a need for a charting and routing system that is as up to date as a continually-changing waterway. This NOAA statement gets to the heart of the problem: “Last year, Coast Survey investigated problems reported with the magenta line. After receiving reports of groundings by boaters who followed the line into shoals, Coast Survey started to remove the magenta line from Intracoastal Waterway nautical charts.” The magenta line as in . . .


At its inception in 1912, the magenta line was state of the art, however fallible. As of now, NOAA has brought back the magenta line, but at the pace of government: “Resolving chart discrepancies will take . . . up to five years or even longer. In cases where information is lacking and the line depiction can lead to risky navigation, Coast Survey will remove that portion of the line.”

Editorial aside not required. Steamboat ICW

The world is moving on. “With the number of contributors that we already have,” Ruge says “we can synthesize the most frequently-traveled routes with timely updates. We had planned to develop this, because we saw the sheer numbers of people contributing and the capabilities it offered. Then NOAA motivated us to move faster.”

With Raymarine becoming a compatible contributor to Navionics’ sonar-log data, the user base in 2014 will grow. The “community edits” option allows users to add information about fuel prices, random flotsam, whatever they think might be useful, and the process is open-ended. “We don’t mind being contacted by anyone who might want to contribute more than sonar data,” Ruge says. “Maybe there’s something in it in exchange for an open dialogue.”

And with that as an invitation, Shaun, the editor in me just has to let you know that I appreciate viewing the Navionics web app online, but when I pull up my home waters of San Francisco Bay and look at the listings for Sausalito, I can’t help thinking you want to send somebody in to correct Item 22, “Clipper Yatch Harbor.”

Happy to help.

Suns New Jerseys