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.
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.
Recently, NOAA navigation response team 5 (NRT5), responded to a survey request from U.S. Coast Guard (USCG) Sector New York following several groundings near Rockaway Point in Queens, New York. Waves and currents often influence the size and shape of nearshore sandbars, and the USCG was concerned that a sandbar may have expanded beyond the area depicted on the nautical chart. Lt. j.g. Dylan Kosten, Eli Smith, and Michael Bloom traveled from New London, Connecticut, to Jersey City, New Jersey, to launch their vessel and start the survey of the area.
The location of the shoal and characteristics of the sandbar created challenging conditions for the survey team. In addition, the crew was asked to survey at a tighter contour (6-foot) than the standard 4-meter (13.1-foot) contour so that they could more clearly define the boundaries of the shoal. To fulfill this requirement, the crew of NRT5 took strong precautions to mitigate risks associated with surveying in shallow water with breaking waves and strong currents, and closely monitored conditions for changes throughout the day.
Conditions changed quickly. The northeast experienced unseasonably warm temperatures, and a thick blanket of fog engulfed New York Harbor as the warm air met the cold water of the ocean, harbors, and bays. With weather conditions thought to be better outside of the harbor and to likely improve later in the morning, the team cautiously transited to the project area and found conditions were indeed much more favorable.
Despite the challenges, NRT5 successfully completed the survey of the area by the end of the week. While the 6-foot contour was not reached in all areas due to breaking waves, the data was interpolated to that scale using lines of data run across the shoal in between wave sets. NRT5 has processed and analyzed the acquired data and Coast Survey will use it to create products to improve the resolution of the charted shoal and prevent future incidents.
Coast Survey’s NRTs conduct hydrographic surveys to update NOAA’s suite of nautical charts. The teams are strategically located around the country and remain on call to respond to emergencies speeding the resumption of shipping after storms, and protecting life and property from underwater dangers to navigation. NRT5 team members contributed the content of this story.
How tall is that rock, really? Is that islet charted correctly? Mariners will have greater confidence in the location and height of charted features as NOAA’s hydrographic ships increase their use of newly adopted laser technology to measure and locate topographical features like rocks, islets, and small islands.
“Fairweather used this laser throughout this past season for feature attribution, and I was tasked with creating the procedures and training other ships,” Debroisse reports. “Rainier will be the next ship to receive the lasers, followed by the East Coast ships [Thomas Jefferson and Ferdinand R. Hassler].”
NOAA charts features such as rocks, piles, islets, kelp beds, and buoys, to give the mariner a clear picture of the dangers that could be in the area. Along Alaska’s and Maine’s rocky shores, for instance, features can be especially important because the tide ranges can be large. It’s especially important to accurately measure a rock at low tide, so a mariner will know its depth when they can’t see it at high tide.
Charted features are also used for visual points of reference during navigation.
Until recently, hydrographic ships’ launches were used to locate the features. To get a reasonable location, the launch would carefully approach the rock or other feature, and “kiss” it with their bow. They would then add the five feet from the boat’s GPS unit to the feature, and mark it on their field hydrographic sheets for use by the cartographers. If the seas are too heavy, or the area too rock-strewn, the surveyors stand on the ship or shore, and use a hand-held laser range finderto measure the height and distance of the feature, and then note the time so it can be corrected for the tide.
This laser technology will be safer than using a launch, and more precise than is possible with the human eye. The laser uses focused light to find and place objects accurately, similar to the way sonar is used to find the seafloor. The laser head produces sixteen laser beams, which reflect off the target object and are received back by the laser head. The computer then uses that data, along with precise positioning and attitude (roll, pitch, and yaw — or orientation) data, to determine the height and location of the object.
These infrared lasers are invisible and completely safe to the eyes of humans and any animals in the area. Also, unlike airborne lidar units that obtain shallow water bathymetry, the ships’ laser cannot penetrate the water.
“Fairweather worked with the Coast Survey Development Lab to test this laser scanner, to determine its feasibility as a topographical tool in the Alaskan environment,” Debroisse says. “We found that this laser method increased the speed and accuracy of data acquisition, and increased the safety of the boat crews completing these surveys.”
And safety, after all, is important for everyone from the NOAA charting teams to the millions of chart users.