Thoughts on NOAA’s Planned Phase-Out of Raster Charts

Below is the feedback I have offered in response to NOAA’s request for public comment on the elimination of raster charts.


I am writing in response to NOAA seeks public comment on ending production of traditional paper nautical charts.

Executive Summary

The move from raster to ENC charts is inevitable, and I am confident in NOAA’s ability to generate high quality ENC charts that enhance the safe passage of mariners. However, two crucial ingredients are needed before a complete transition from raster charts can occur without exposing mariners — recreational, in particular — to danger:

  1. ENC chart creation. A precisely defined and rigorous process to ensure navigational hazards appear on all scales of the ENC chart(s) for a given area.
  2. ENC chart rendering. Appropriate standards and certifications relating to the rendering of ENCs, with an emphasis on safety and the display of hazards.

ENC Chart Creation

Several navigational incidents have emerged in recent years relating to the use of ENCs.

As described in What The Volvo Race Crash Teaches Boaters by Susan Shingledecker:

In the case of the Vestas Wind grounding, the smaller-scale e-chart (1:1,000,000) showed water depths of approximately 40 meters, with no indication of a reef or other obstruction to navigation. However, the larger-scale e-chart (with a more zoomed-in scale of 1:75,000) clearly showed the reef, and so does the paper chart of that region of the ocean. […] “To see the reef on our electronic charts, you have to zoom right in on top of it. But how and why would you zoom in to it if you don’t know [the hazard] was there in the first place?”

See also Electronic charts and grounding – a cautionary tale by Chris Beeson.

The creation of raster charts relies on intelligent human judgment for the inclusion of hazards to navigation on the charts of differing scales. In the Vestas Wind incident, it is clear that the issue lies in the ENC chart data, which clearly has room for improvement.

I urge NOAA — if it hasn’t already — to establish a clearly-defined and rigorous process, whether it be mechanical or human in nature, for ensuring that hazards to navigation appear in all scales of ENC charts, and, furthermore, to share this definition and/or process with other (perhaps commercial) chart makers for the benefit of all mariners.

This is a necessary step before ENC charts can be relied upon for safe navigation.

ENC Chart Rendering

With raster charts, what you see is what you get. Mariners see the chart exactly as the cartographer created it. When using raster charts, I have confidence that I am seeing on there what needs to be seen.

However, with ENC charts, an additional layer is introduced between the cartographer and the mariner — the rendering process.

Rendering processes include ECDIS displays, navigational software for computers and tablet devices, as well the NOAA Custom Chart tool.

As a consumer of recreational marine software and equipment, how can I be confident that a particular rendering of an ENC chart is showing what needs to be seen, even in the event that the provided ENC chart data is complete and flawless?

A set of comprehensive standards and certifications is necessary to ensure that important details of ENC rendering is consistent across software and devices from all vendors, particularly in the area of safety and displaying hazards to navigation.

I have confidence in NOAA’s ability to create detailed, quality, and safe ENC charts. I have little faith in the consumer marine equipment and software market to display ENC charts in a consistently safe manner.

NOAA’s own Custom Chart tool has a long way to go before it can realistically be used to generate charts that can be relied on for safe navigation. This is stated not as criticism, but rather to highlight the inherent and complex challenges present in ENC rendering.

The IMO’s ECDIS Performance Standards (MSC 232(82)) are a good start, however there are two key issues with it:

  1. The standards, in my opinion, do not go into deep enough detail about how ENC charts are to be rendered to ensure a level of safety better than, or at least consistent with, the use of raster charts.
  2. The standards, while not explicitly excluding recreational vessels, appear to be authored primarily with commercial vessels in mind. The commercial and recreational markets for navigational displays and devices are quite different, and I have little faith in the recreational market absent well-defined standards and independent, third-party certification processes.

The fact that ENC charts are now mandatory on some commercial vessels, crewed by professionals, says little about their appropriateness and readiness for recreational mariners and vessels, nor the equipment and software available to them.

Thank you for providing the opportunity to voice my concerns, and for taking the time to consider these words.

Best wishes,

Chuck Batson
San Rafael, CA

Raster chart of the entrance to San Francisco Bay.
The same chart generated from ENC data using the NOAA Custom Chart prototype.
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