Navigating waters before GPS: Why some mariners still refer to Loran-C

by Nick Perugini

One of the most popular recurring questions received by NOAA’s Office of Coast Survey involves customers – typically fishermen – wanting to obtain a chart with a Loran-C navigation grid on it. Here are a few inquiries from NOAA’s Nautical Inquiry & Comment System:

  • Hello, I was wondering if it is still possible to purchase or locate older editions of Lake Huron charts (14862-3-4) with the LORAN-C overlay. Many older wrecks and reported snags are still in Loran and have not been converted to GPS. Artificial algorithms are difficult to use when plotting grids. Any help you can give me is much appreciated.
  • Is it possible to access Loran-C charts of New England from prior to 2009 when NOAA stopped published with the LORAN-C lines? THANKS!
  • I was wondering if there was a way for me to buy a chart that has LORAN lines and notes on it? I understand that all of the new charts no longer have this information on them. I am most interested in Chart 11520, Cape Hatteras to Charleston. I didn’t know if there might be an archived form of this chart that shows the LORAN features. Any help in finding a chart like this would be greatly appreciated.

A quick history lesson on Loran-C: Loran (Long range navigation) was a hyperbolic radio navigation system developed in World War II. Loran grid lines (actually hyperbolas) first appeared on nautical charts during the 1950’s. The intersection of these electronic lines of position generated from shore transmitters provided mariners with accurate positions, within hundreds of feet, as their vessels operated nearshore as well as many hundreds of miles offshore. In the 1970’s, the U.S. Coast Guard (USCG) upgraded Loran-A to Loran-C, a system that was even more accurate and much easier to use.

However, positioning technology marches on. With the dawning of a high accuracy Global Positioning System (GPS) in the early 1990s, Loran-C slowly became antiquated and finally the USCG took Loran-C transmitting stations offline in 2010. With no Loran-C signal, Coast Survey followed suit and began to eliminate Loran-C lattices from nautical charts. Most charting customers welcomed the removal of the busy lattices from the chart as it made the chart more readable.

The entrance to the Chesapeake Bay, Chart 12221, with a Loran-C grid on the 2009 edition (left) and without Loran-C (right).
The entrance to the Chesapeake Bay, Chart 12221, with a Loran-C grid on the 2009 edition (left) and without Loran-C (right).

So why do some people still want nautical charts with a Loran-C lattice? Prior to GPS, many fishermen and commercial diving operations did not use a true latitude and longitude (Lat/Lon) geographic coordinate system to position their offshore features. They identified their favorite fishing or diving locations by Loran-C time delay coordinates. When Loran-C lattices were removed from NOAA charts, many fishermen were left with Loran-C coordinates that had no corresponding Lat/Lon. Therefore, they did not have a way of plotting their Loran-C coordinates on current charts.

The Office of Coast Survey Historical Map & Chart Collection provides one way to address the problem. Users can find editions of their charts published prior to 2010 that would likely contain a Loran-C lattice. While historical charts should not be used for navigation today since they have not been updated, they can be used to convert Loran-C coordinates to Lat/Lon (GPS coordinates). Customers can download charts as high-resolution images, transfer the files to a flash drive, and take it to a local printer who can print the charts in a large format. Alternatively, some electronic chart systems allow you to display Loran-C lattices over current up-to-date charts, or to import a chart image, define its Lat/Lon origin, and utilize it with chart plotter software.

So is Loran gone forever? Not quite. In fact, Loran is making a comeback as Enhanced Loran, i.e. “eLoran.” With increased awareness of the vulnerabilities of satellite positioning systems, there is a growing consensus in the national security community that an independent back-up positioning system is required. The USCG and other organizations within the Department of Homeland Security are conducting tests on eLoran. Like the original Loran-C, the new system would have shore-based transmitters that generate hyperbolic grids. Unlike the old system, eLoran would be much more accurate with differential corrections built into the signal transmissions. When and if eLoran comes to fruition, you will not see Loran grid lines returning to NOAA charts since receivers will likely be working in a Lat/Lon coordinate system.

Online NOAA Custom Chart lets boaters create their own charts

A prototype version of a powerful new online tool, NOAA Custom Chart, is now available for boaters and other nautical chart users. The application enables users to define the scale and paper size of custom-made nautical charts centered on a position of their choosing. Once the functionality of this prototype is fully developed, NOAA Custom Chart will be an easy way for boaters to create a paper or digital back-up for the electronic chart system or other GPS-enabled chart display that they are using on board.

NOAA Custom Chart creates a geospatially referenced PDF (GeoPDF) from the NOAA electronic navigational chart (NOAA ENC®) database. In the final operational version of the application, chart notes and other margin notes will be placed at the bottom, below the chart neatline, similar to USGS topographic (US Topo) maps. The user may download, view, and print the output.

NOAA Custom Chart makes it easy for users to create a personalized chart.
NOAA Custom Chart makes it easy for users to create a personalized chart.

There are several options for customizing the appearance of the chart data. The prototype creates charts with either the “traditional” or “simplified” symbology of the Electronic Chart Display and Information Systems (ECDIS) used by professional mariners. Future versions of NOAA Custom Chart will add a full paper chart symbology option.

U.S.CustomChart_Interface
Simple interface lets users choose a scale, paper size, and the center of their own chart.

If you are interested in customizing your own nautical charts, visit NOAA Custom Chart. Then tell us your ideas for improving it through NOAA’s Nautical Inquiry & Comment System. 

 

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.

merrimack-tileservice3
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.

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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.

TampaBay_SunshineSkywayBridge

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.