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.
Recently, Lt. j.g. Patrick Debroisse, junior officer on NOAA Ship Fairweather, trained his NOAA Ship Rainier colleagues on how to use the topographic laser that they will soon be receiving.
“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.
This area on chart 16604 illustrates features that could use the precision of topographic laser scanning.
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.
One of Rainier‘s four launches at work in Uganik Bay.
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.
Illustrated by Kristen Crossett, NOAA Office of Coast Survey
Thanks to a combination of determination and technical advancements, Coast Survey was able to locate, report, and chart a danger to navigation within two weeks – a major improvement over the three-to-ten-year chart update protocol of only a few years ago.
On Monday, November 14, a Coast Survey navigation response team hit the waters of St Simons Sound, off the coast of Georgia, when the U.S. Coast Guard asked us to find a sunken fishing vessel. By the next morning, the team of James Kirkpatrick and Kyle Ward (who augmented on the project, from his normal duty as navigation manager in Charleston), reported to the Coast Guard, noting that the wreck is very shoal. They also observed recreational vessels transiting the area every 10 to 15 minutes. Coast Survey quickly issued an official Danger to Navigation Report.
Location of the wreck
Wreck as seen with multibeam echo sounder
Wreck as seen with side scan sonar
The team’s hydrographic data determined a least depth of 0.4 meters (1.3 feet) at position 31-07-34.41N// 081-25-15.88W. The vessel appears to be lying on its port side with the bow pointing in an approximate SE orientation with the stern slightly higher than the bow. The least depth appears to be on some type of rigging or fishing gear protruding from the midship area.
Recognizing that a boat could easily hit the submerged wreck, the navigation response team asked Coast Survey cartographers to quickly add it to the charts. The cartographers acted immediately, applying the wreck symbol to paper, raster, and electronic charts of the area. The cartographers, working with branch chief Ken Forster, will publish the updated charts with the next cycle of weekly updates, scheduled for Wednesday, November 23.
Coast Survey is updating charts 11506 and 11502, and ENCs US5GA13M and US4GA11M
Finding and charting dangers to navigation are our highest priorities. We encourage mariners who suspect dangers, or who want to report any chart discrepancy, to file a fast and easy report on our website.
NOAA has issued a new nautical chart for the Port of Palm Beach, Florida, an important distribution center for commodities being shipped all over the world, and especially the Caribbean Basin.
The Port of Palm Beach operations include containerized, dry bulk, liquid bulk, break-bulk, and heavy-lift cargoes. It is the only port in South Florida with an on-dock rail where the Florida East Coast Railway provides twice-daily service to the port’s rail interchange.
The Palm Beach Harbor Pilots Association asked Coast Survey for the new chart, citing the dangers confronting navigators who approach the port and anchor offshore using the small scale coverage and corresponding lack of detail currently available on chart 11466 (1:80,000). With more and bigger vessels entering the port, the larger scale inset helps pilots navigating within the turning basin and surrounding infrastructure. This is especially important because it is located within the traffic flow of the Intracoastal Waterway.
In consultation with the Palm Beach Pilots, the U.S. Coast Guard Sector Miami, Port of Palm Beach (Operations Division), and the Army Corps of Engineers Jacksonville District, Coast Survey developed the new chart specifications. All parties agreed that the new 1:15,000 scale chart and a 1:5,000 scale inset would enhance navigational safety and greatly benefit port operations.
In order to create the new chart, new data had to be collected. The National Geodetic Survey’s Remote Sensing Division collected additional bathymetric lidar data along the shoreline and Coast Survey’s navigation response team collected hydrographic data in the area just beyond where the U.S. Army Corps of Engineers data ends.
A larger scale chart for the Port of Palm Beach required additional data be collected by the National Geodetic Survey’s Remote Sensing Division and Coast Survey’s navigation response team.
History is never completely written. There are always new discoveries, new understanding.
NOAA historian John Cloud recently sent Coast Survey an intriguing report:
Yesterday I was looking for some historic Chesapeake Bay T sheets [topography drafts]… Anyway, down in the bottom of a folder, there was a zipped file, dated 2009, never unzipped. I thought: well, since I have noticed this now, why don’t I unzip it? It turned out to be two overly rescaled jpgs, but using my Keith Bridge tricks [a technique developed by a former Coast Survey historical chart expert] I found the two full-scale originals. It was one chart, with a small part cut off to make two separate files: the original 1838 hydrography for New Haven Harbour!
This is the basis for the 1838 engraved chart for Congress, the second published Coast Survey chart. (The first was based on Lt. Gedney’s partial survey of Newark Bay, NJ and the mouth of the Hackensack River, 1837.) The New Haven work was 1838. In 1839, the same Lt. Gedney and company captured the slave ship Amistad and brought the ship and captives to New Haven, claiming the escaped slaves as property. [UPDATE, 10/27/2016: Delving deeper into Gedney’s actions, it turns out he docked the ship in New London, while the captive Africans were brought to New Haven.] Then later, John Quincy Adams persuaded a judge they had freed themselves on the boat and were no longer slaves.
Unzipping the files happened within an hour or so of getting an email from Michelle Zacks, a scholar of marine environmental history who has explored historic Coast Survey field survey notebooks as sources for her ongoing project on the antebellum oyster industry and the lives of enslaved and free African Americans in the Chesapeake region. That research helped lead to her new job, as the associate director of the Gilder Lehrman Center for the Study of Slavery, Resistance, and Abolition, at Yale, which is in: New Haven!
It all happened just like that! Like the chart “wanted” to emerge back into the Amistad story.
We weren’t able to trace the origination of that zip file, but it was obviously created by someone who didn’t realize the value of the historical images. And this, ladies and gentlemen, is why we value historians.