NOAA RNC Tile Service displays first ENC-only product

NOAA Office of Coast Survey released its 1:12,000 electronic navigational chart (NOAA ENC®of the Merrimack River, Massachusetts, in the RNC Tile Service. This is the first time a navigational chart—created solely as ENC product—is included in the tile service. The tile service renders a traditional depiction of the nautical chart for use with GPS-enabled electronic chart systems or other “chart plotter” display systems to provide real-time vessel positioning for recreational mariners. This chart is included in the single chart tile sets and the quilted tile sets both in the online and offline versions.

The Merrimack River, located in Massachusetts, is just south of the New Hampshire border.The single chart tile set is named​ 13274K0000_1.
The Merrimack River, located in Massachusetts, is just south of the New Hampshire border. The single chart tile set for this area is named​ 13274K0000_1.

The tile service version of the Merrimack chart retains the look of a NOAA paper chart but is derived from the ENC charting database. This gives users the opportunity to use ENC-only data with a traditional NOAA chart feel. NOAA intends to incorporate all future charts that are produced only as ENCs into the tile service (ENC-only charts are outlined in the National Charting Plan, page 25).

“This release represents a major milestone in nautical charting,”  said Rear Admiral Shepard Smith, the director of Coast Survey.  “This is the first chart that was digital from its inception, breaking with the longstanding practice of digital charts based on paper charts.”  

For professional mariners, it is important to note that there is no paper chart equivalent, and that this chart will not be served by the Notice to Mariners systems provided by the U.S. Coast Guard and National Geospatial-Intelligence Agency.  Updates will be made as necessary by NOAA weekly.  Customers with compatible applications will get the updates automatically.

The original 1:12,000 ENC of the Merrimack River was released at this time last year. Recognizing the need for a more detailed chart, a group of local and state stakeholders concerned with the economic revitalization of the area contacted NOAA to create a new, larger-scale chart. The new, larger-scale ENC was compiled using U.S. Army Corps of Engineers data, NOAA lidar data, and privately funded survey data. When shown in detail, the combined data provides mariners with a clearer picture of the overall conditions and dangers to navigation. The availability of this chart in the RNC tile service provides mariners greater flexibility in viewing the chart.

This update to the RNC tile service also includes the ArcGIS Tile Metadata Service, adding support for source chart metadata from within ArcMap and other GIS applications. Instructions for loading the tile metadata into ArcMap have been added to the developer’s website.

Instructions for loading tile metadata into ArcMap are available from the tile service website.

The ArcGIS Tile Metadata Service can be accessed from a web application, as shown below in our ArcGIS sample viewer for the quilted tile set.

ArcGIS sample viewer for the quilted tile set.



NOAA surveys for recreational boat traffic safety in Tampa Bay

NOAA’s navigation response team 2 (NRT2), homeported in Fernandina Beach, Florida, conducted a survey around the Sunshine Skyway Bridge, which spans Tampa Bay. The U.S. Coast Guard (USCG) and additional members of the Tampa Bay Harbor Safety Committee requested the work and expressed interest in establishing alternate routes for recreational boating traffic. Alternative routes will alleviate increasing congestion where the main ship channel passes beneath the bridge. This area is naturally restrictive to navigation and, as a result, there have been multiple accidents and near accidents here in the past.

Multibeam echo sounder coverage. Credit: NOAA
Multibeam echo sounder coverage. Credit: NOAA

Lt. j.g. Patrick Debroisse from NOAA Research Vessel Bay Hydro II installed a topographic lidar system on NRT2, which marked the first time a lidar system was employed from an NRT boat. The lidar system enabled 3D data to be collected for those portions of the bridge that are above water line. NRT2 collected lidar data for associated bridge protective structures and two fixed light range towers in addition to the bridge and bridge supports.   

The accurate positional and dimensional information gleaned from this data will be used to compliment extensive hydrographic sonar data collected beneath the surface. Together, the complete data set will enable full consideration of area features, both above and below the water line, in determining the placement of alternative routes.


The center spans of the Sunshine Skyway Bridge (left) were successfully captured from lidar data (right). Photo credits: NOAA
The center spans of the Sunshine Skyway Bridge (above) were successfully captured from lidar data (below). Credits: NOAA

A USCG approval decision is anticipated in the spring. If approved, the chief of the cartographic team will work to have the alternate routes added to all affected NOAA charts.

The NRT2 team consists of James Kirkpatrick (team lead), Lucas Blass, and Howie Meyers. NOAA’s NRTs operate trailer-able survey launches to provide time-sensitive information during emergency response and maritime incidents such as vessel groundings, sinkings, or cargo loss. The launches are equipped with multibeam and side scan sonar, which can help identify navigation hazards and mitigate risk to life and property.

The largest scale raster navigational charts of this area, charts 11415 and 11416, are available online.

NOAA Coast Survey offers new certification program in nautical cartography

The International Board on Standards and Competence for Hydrographic Surveyors and Nautical Cartographers (IBSC) recognized and approved Coast Survey’s new certification program in cartography (CAT-B) at their 40th meeting in Willington, New Zealand. Capt. Andy Armstrong (NOAA, ret.), co-director of the Center for Coastal & Ocean Mapping/Joint Hydrographic Center at the University of New Hampshire, presented the program at the meeting.

Capt. (NOAA ret.) Andy Armstrong (left) with IBSC Chair, Mr. Adam Greenland (right) at the 40th meeting of the IBSC in Willington, New Zealand.
Capt. Andy Armstrong (left) with IBSC Chair Adam Greenland at the 40th meeting of the IBSC in Willington, New Zealand.

The new program will grant certificates to up to 13 cartographers per year, through a combination of lectures, hands-on chart production experience, work details to various branches within the Coast Survey, and field trips to working hydrographic survey vessels. The first class (which is already full), will begin in fall 2017 at Coast Survey headquarters in Silver Spring, Maryland. The duration of the program is 51 weeks and comprises six courses:

A refresher course will review basic math, computer and communication technology, marine geography, hydrography, and geodetic topics.

Introduction to cartography course (provided by Montgomery College) will review elements of cartography; specifically scale, design, and data manipulation techniques.

GIS and spatial analysis course (provided by University of Maryland, College Park) will provide a comprehensive understanding of spatial analysis methods and practical experience using GIS.

Map design course (provided by Montgomery College) will offer hands-on experience using various styles and techniques associated with cartographic design, including analysis of chart design parameters and compilation of thematic cartographic projects.

GIS and spatial modeling course (provided by University of Maryland, College Park) will give the student a foundation and understanding of various issues related to modeling and simulation in GIS, including concepts, tools, and techniques of GIS modeling (vector- and raster‐based modeling).

NOAA training project and 12-week internship program will include: 1) a detailed review of many of the activities conducted by the branches in Coast Survey’s Marine Chart Division; and 2) a training project that demonstrates the student’s ability to implement the knowledge gained during the certification.

Coast Survey plans to offer this program on annual basis. Registration for the 2018 session will be announced next January.

Beta test of crowdsourced bathymetry holds promise for improving U.S. nautical charts

We are on the verge of acquiring a significant new source of data to improve NOAA nautical charts, thanks to an enthusiastic industry and mariners equipped with new technology.

By Lt. Adam Reed, Integrated Oceans and Coastal Mapping (IOCM) Assistant Coordinator

The United States has about 3,400,000 square nautical miles of water within our coastal and Great Lakes jurisdiction. Coast Survey, who is responsible for charting that vast area, averages about 3,000 square nautical miles of hydrographic surveying each year. The data collected by those surveys update over a thousand NOAA charts. However, hydrographic surveys are expensive and laborious, and so Coast Survey directs them toward the highest priority sites, which leaves many coastal areas without updates for many years.

Coast Survey may soon get new sources of information, provided voluntarily by mariners, which will alert cartographers to areas where shoaling and other changes to the seafloor have made the chart inaccurate.

Rose Point Navigation System beta tests new crowdsourcing database

Technology has reached the point where any boater can buy an echo sounder kit, add a GPS system, record depth measurements, and make their own geospatial observations in a common reference frame. The question then for hydrographic offices (who are concerned with improving nautical charts for safe navigation) becomes “how do we take advantage of that?”

Rose Point Navigation Systems is working with system developers at NOAA’s National Centers for Environmental Information (NCEI) and with hydrographic experts at Coast Survey and others who are collaborating on an international effort to maintain crowdsourced bathymetry. In a beta test released on May 13, 2016, Rose Point has added a new feature to Coastal Explorer that gives users an option to send anonymous GPS position and soundings data to a new international database managed by NCEI. After getting permission from users, Rose Point systems will generate data log files of positions, depths, and time, and automatically transmit the files to the data center, where Coast Survey can pull the data to compare it to nautical charts.

Crowdsourced bathymetry is an international project

Using data from private sources is not new for Coast Survey. Private interactive cruising guides and other internet-based enterprises have set up services that allow commercial mariners and recreational boaters to share information about navigation hazards they see (or experience) while on the water. The United States Power Squadrons and the U.S. Coast Guard Auxiliary have a decades-long tradition of sharing updates through our cooperative charting programs. But the lack of appropriate software and integration between sources has hampered efforts to use the information to its full potential.

Hydrographic offices around the world are re-thinking crowdsourced bathymetry. In October 2014, Coast Survey led the U.S. delegation to the Fifth Extraordinary International Hydrographic Conference, with Rear Admiral Gerd Glang at the helm. At this meeting, the U.S. and France jointly proposed an initiative (see Proposal No. 4) that introduced crowdsourced bathymetry as a recognized source of data for nautical charts. One of the results of that initiative was the formation of the IHO Crowdsourced Bathymetry Working Group (IHO CSBWG) that set out to develop crowdsourcing principles and guidelines, and then offer a platform for sharing best practices around the world.

Working hand-in-hand with NCEI, the working group has developed a database that can receive volunteered bathymetric data. Data can come from anyone in the world, and everyone can access it.

Coast Survey will use crowdsourced bathymetry to assess chart accuracy

Crowdsourced reports serve an important role in focusing attention on trouble areas. The data helps cartographers determine whether a charted area needs to be re-surveyed, or if they can make changes based on the information at hand. Even with very sparse data, cartographers can make improvements to nautical charts.

Agreeing in principle to use crowdsourced data is much different than applying the system to the vigor of data transmission from moving vessels, however, so Coast Survey experts contributed hydrographic expertise and system testing. Using Rose Point’s Coastal Explorer, Coast Survey Research Vessel Bay Hydro II transmitted “crowdsourced” data using log files that were automatically produced by the electronic charting system software. (Bay Hydro II is Coast Survey’s primary platform to test and evaluate new hydrographic survey technologies.)

BHII bathymetric data collection
Coast Survey Research Vessel Bay Hydro II collected about 123,000 soundings, over 12 days, to pre-test the efficacy of Rose Point beta test for bathymetric crowdsourcing.

“When you aggregate crowdsourced data, we can expect to see trends develop where the seafloor has likely changed from charted data,” explains Lt. Anthony Klemm. “Using Bay Hydro II data transmissions, we saw such trends indicating shoaling near the Patuxent river entrance. Similarly, in the approach to Solomons harbor, trends displayed depths deeper than charted.”

It is important to emphasize that Coast Survey does not necessarily make changes to any significant charted feature based on crowdsourced data alone. That data, however, is about to become a major factor in making charts better.

How accurate are nautical charts?

Charts will provide more information on “zone of confidence”

It is a major challenge – some might say an impossibility – to keep all thousand U.S. nautical charts up to date. But exactly how out of date is the chart data? Chart users will get a better idea now that Coast Survey is gradually rolling out a new chart feature called the zone of confidence, or “ZOC” box. It will replace the source diagram that is currently on large-scale charts. Source diagrams, and now the improved ZOC, help mariners assess hydrographic survey data and the associated level of risk to navigate in a particular area.

The first charts to show the new ZOC box are 18622, 18682, 18754, and 11328. They were released on April 7.

Both source diagrams and ZOC diagrams consist of a graphic representation of the extents of hydrographic surveys within the chart and accompanying table of related survey quality categories. Where the old source diagrams were based on inexact and sometimes subjective parameters, however, the new ZOC classifications are derived more consistently, using a combination of survey date, position accuracy, depth accuracy, and sea floor coverage (the survey’s ability to detect objects on the seafloor).

To see the zones of confidence on charts, look for the chart markings (A1, A2, B, C, and D) on the chart itself. Check the ZOC box (located on non-water portions of the chart) for the date of the data acquisition, the position accuracy, the depth accuracy, and characterization of the seafloor for each particular zone.

ZOC categories

Why do users need a “zone of confidence?

The age and accuracy of data on nautical charts can vary. Depth information on nautical charts, paper or digital, is based on data from the latest available hydrographic survey, which in many cases may be quite old. In too many cases, the data is more than 150 years old. Sometimes, particularly in Alaska, the depth measurements are so old that they may have originated from Captain Cook in 1778.

Mariners need to know if data is old. They need to understand the capabilities and the limitations of the chart. In particular, the mariner should understand that nautical chart data, especially when it is displayed on navigation systems and mobile apps, possess inherent accuracy limitations.

Before the advent of GPS, the position accuracy of features on a paper chart was more than adequate to serve the mariner’s needs. Twenty years ago, mariners were typically obtaining position fixes using radar ranges, visual bearings, or Loran C. Generally, these positioning methods were an order of magnitude less accurate than the horizontal accuracy of the survey information portrayed on the chart. Back then, Coast Survey cartographers were satisfied when we plotted a fix with three lines of position that resulted in an equilateral triangle whose sides were two millimeters in length at a chart scale of 1:20,000. In real world coordinates, the triangle would have 40-meter sides. Close enough!

Now, with GPS, charted locations that are off by 10 or 15 meters are not nearly close enough. Mariners now expect, just as they did 30 years ago, that the horizontal accuracy of their charts will be at least as accurate as the positioning system available to them. Unfortunately, charts based on data acquired with old survey technologies will never meet that expectation.

Source data is deficient by today’s standards

The overall accuracy of data portrayed on paper charts is a combination of the accuracy of the underlying source data and the accuracy of the chart compilation process. Most nautical charts are made up of survey data collected by various sources over a long time. A given chart might encompass one area that is based on a lead line and sextant hydrographic survey conducted in 1890, while another area of the same chart might have been surveyed in the year 2000 with a full-coverage shallow-water multibeam echo sounder.

In general, federal hydrographic surveys have used the highest standards, with the most accurate hydrographic survey instrumentation available at the time. On a 1:20,000-scale chart, for example, the survey data was required to be accurate to 15 meters. Features whose positions originate in the local notice to mariners, reported by unknown source, are usually charted with qualifying notations like position approximate (PA) or position doubtful (PD). The charted positions of these features, if they do exist, may be in error by miles.

Similarly, the shoreline found on most NOAA charts is based on photogrammetric or plane table surveys that are more than 30 years old.

Another component of chart accuracy involves the chart compilation process. Before NOAA’s suite of charts was scanned into raster format in 1994, all chart compilation was performed manually. Cartographers drew projection lines by hand and plotted features relative to these lines. They graphically reduced large-scale (high-detail) surveys or engineering drawings to chart scale. Very often, they referenced these drawings to state or local coordinate systems. The data would then be converted to the horizontal datum of the chart, e.g., the North American 1927 (NAD27) or the North American Datum 1983 (NAD83). In the late 1980s and early 1990s, NOAA converted all of its charts to NAD83, using averaging techniques and re-drawing all of the projection lines manually.

When NOAA scanned its charts and moved its cartographic production into a computer environment, cartographers noted variations between manually constructed projection lines and those that were computer-generated. They adjusted all of the raster charts so that the manual projection lines conformed to the computer-generated projection.

Many electronic chart positional discrepancies that are observed today originate from the past graphical chart compilation techniques. The manual application of survey data of varying scales to the fixed chart scale was a source of error that often introduced biases. Unfortunately, on any given chart, the magnitude and the direction of these discrepancies will vary in different areas of the chart. Therefore, no systematic adjustment can automatically improve chart accuracy.

Coast Survey is addressing the accuracy problem

NOAA’s suite of over a thousand nautical charts covers 95,000 miles of U.S. coastline, and includes 3.4 million square nautical miles of U.S. jurisdiction within the Exclusive Economic Zone (which is an area that extends 200 nautical miles from shore.) About half of the depth information found on NOAA charts is based on hydrographic surveys conducted before 1940. Surveys conducted with lead lines or single-beam echo sounders sampled a small percentage of the ocean bottom. Due to technological constraints, hydrographers were unable to see between the sounding lines. Depending on the water depth, these lines may have been spaced at 50, 100, 200, or 400 meters. Today, as NOAA and its contractors re-survey areas and obtain full-bottom coverage, we routinely discover previously uncharted features (some that are dangers to navigation). These features were either: 1) not detected on prior surveys; 2) man-made objects, like wrecks and obstructions, that have appeared on the ocean bottom since the prior survey; or 3) the result of natural changes that have occurred since the prior survey.

Coast Survey is also improving our chart production system. As NOAA developed its charts over the centuries, cartographers relied on separate sets of data: one set for traditional paper charts, and another for the modern electronic navigational charts. We are currently integrating a new charting system that will use one central database to produce all NOAA chart products. The new chart system slims down the system while it beefs up performance, speeding new data and updates to all chart versions of the same charted areas and removing inconsistencies.

As always, NOAA asks chart users to let us know when you find an error on a NOAA chart. Just go to the discrepancy reporting system, give us your observation, and we will take it from there.

New tips for understanding nautical chart symbols

SymbolGlobeAs a responsible boater, you examine your nautical chart before sailing, determined to avoid problems during a nice trip along the coast. Charts are packed with symbols and abbreviations, so you might refer to the free copy of U.S. Chart No. 1, which lists all of the symbols used on NOAA nautical charts. It is an excellent quick reference for identifying unfamiliar symbols.

However, sometimes mariners need a deeper understanding…

Coast Survey is now providing additional information about complex or particularly confusing chart symbols to augment what is available in U.S. Chart No. 1. The first two tip sheets are available now. Coast Survey will add more chart symbology tip sheets to the U.S. Chart No. 1 webpage as the need arises.

Understanding NOAA chart symbology

K46.1 - FishHaven

Fish havens: The typical U.S. Chart No. 1 entry, such as this one for fish haven, lists only the name and the symbols. The tip sheet explains what fish havens are, what they look like in context with other charted features, and what restrictions may apply to them.


Anchorages and harbors of refuge: The anchor symbol has been used for decades to represent an anchorage on U.S. nautical charts, but the specific meaning of the symbol has evolved over the years. The tip sheet explains what the symbol means now – and, perhaps more importantly, what it doesn’t mean.

Questions or suggestions? Email

NOAA and Cuban chartmakers working together to improve maritime safety

Callender, Gomez, and Glang
NOS Acting Assistant Administrator Russ Callender (left) and Coast Survey Director Rear Adm. Gerd Glang (right) welcome Colonel Candido Regalado Gomez, chief of Cuba’s Office of Hydrography and Geodesy.

Following up on Coast Survey’s visit to Havana last spring, Cuban hydrographic officials traveled to Maryland on December 15-17, to meet with NOAA National Ocean Service leaders for discussions about potential future collaboration. High on the agenda for Coast Survey is improving nautical charts for maritime traffic transiting the increasingly busy Straits of Florida.

The historic meeting began with Dr. Russell Callender, NOS acting assistant administrator, welcoming the Cuban delegation, led by Colonel Candido Regalado Gomez, chief of Cuba’s National Office of Hydrography and Geodesy.

“You will receive briefings today as a backdrop to the hydrographic collaboration we are pursuing to make maritime navigation safer in the transboundary waters our nations share,” Callender told the group. “I hope your meetings this week in Silver Spring will contribute to your understanding of the breadth and work of NOAA firsthand, and strengthen our work together.”

The five Cuban officials and representatives from NOAA’s navigation services and the National Geospatial-Intelligence Agency worked through the day, explaining the ins-and-outs of each other’s responsibilities and processes. The teams were ready, by the end of the jam-packed agenda, to resolve charting challenges that interfere with smooth navigational transitions from Cuban waters to U.S. waters in the busy Straits of Florida.

This heat density map of maritime traffic illustrates the high volume of traffic (the brown area south of Florida) needing seamless chart coverage.

First, Cuba’s Office of National Hydrography and Geodesy and Coast Survey’s Marine Chart Division confirmed the division of responsibilities and updated each other on the progress for collaborating on international charts (known in mariner’s parlance as “INT Charts”) 4148, 4149, 4017, and 4021. Then, in a technical move sure to please recreational boaters and commercial mariners alike, the two countries conferred on adjusting Cuba and U.S. electronic navigational charts to eliminate overlaps and gaps in coverage.

U.S. and Cuban officials
U.S. and Cuban officials met at NOAA Coast Survey offices in Silver Spring, Maryland, for an intensive day of reports and collaboration. From left to right, Dr. Russell Callender, acting assistant administrator for the National Ocean Service; Rear Admiral Gerd Glang, director of Coast Survey; Richard Edwing, director of CO-OPS; John Lowell, the National Geospatial-Intelligence Agency’s chief hydrographer; Tim Wiley, environmental engagement officer, Office of the Coordinator for Cuban Affairs, U.S. Department of State; Captain Richard Brennan, chief of Coast Survey Development Laboratory; Sladjana Maksimovic, Coast Survey cartographer; Edenia Machin Gonzalez, scientist, Cuba’s National Cartographic Agency; Ramon Padron Diaz, frigate captain and chief of Hydrographic Department, Cuba’s National Office of Hydrography; Colonel Candido Regalado Gomez, chief of Cuba’s National Office of Hydrography and Geodesy; and Victor E. Aluija Urgell, lieutenant/general director, GEOCUBA Marine Studies.

By examining adjacent and adjoining ENCs, both sides were able to confer on ways to improve chart coverage in the busy Straits of Florida, where chart misalignments can play havoc with navigational systems as a vessel moves across maritime borders. Countries around the world regularly resolve these issues, as the U.S. does with Canada and Mexico, through regional consultations hosted by the International Hydrographic Organization but, until now, the U.S. and Cuba were unable to work together on their common set of challenges.

Coast Survey initiated the charting discussions earlier this year, when a team of cartographic professionals traveled to Havana in February for three days of meetings with Cuban officials from the Office of National Hydrography and Geodesy and GEOCUBA. During the visit, the Americans and Cubans agreed to work together on a new international paper chart, INT Chart 4149, which will cover south Florida, the Bahamas, and north Cuba. The Office of Coast Survey is now creating the chart, using data supplied by the United Kingdom Hydrographic Office and the Cubans in addition to U.S. data, and plans to publish the new chart in 2016.

This week’s charting progress follows closely on another major accomplishment. Last month, NOAA Administrator Dr. Kathryn Sullivan and Dr. Holly Bamford, acting assistant secretary of conservation and management, traveled to Havana to sign a Memorandum of Understanding on Marine Protected Area cooperation between our two countries. The agreement provides an opportunity for the U.S and Cuba to develop science, education, and management programs between sister sites in both countries, and will strengthen our collaborative relationship.

“The Cuban maritime industry, like many U.S. ports, is building new infrastructure to support commerce and tourism,” said Rear Admiral Gerd Glang, director of Coast Survey. “Like us, they are improving their charts as port and coastal uses evolve, to support expanding maritime commerce.”

“We are now able to work together, as we do with other nations, to coordinate chart coverage and data acquisition.”

Katie Ries with Cuban delegation
In addition to hours of indoor meetings, the Cuban delegation was able to spend some time discussing data acquisition onboard Coast Survey’s research vessel, Bay Hydro II, homeported in Solomons, Maryland. Kathryn Ries (in blue jacket), deputy director of Coast Survey, hosted Ramon Padron Diaz, frigate captain and chief of the Hydrographic Department, Cuba’s National Office of Hydrography; Victor E. Aluija Urgell, lieutenant/general director, GEOCUBA Marine Studies; Edenia Machin Gonzalez, scientist, National Cartographic Agency – Cuba; Yanet Stable Cardenas, first secretary, Embassy of the Republic of Cuba; and Colonel Candido Regalado Gomez, chief of Cuba’s National Office of Hydrography and Geodesy.