What does the age of the survey mean for nautical charts?

Alaska’s nautical charts need to be updated — we all know that. The diagram below shows the vintage of survey data currently used for today’s charts in Alaska. The graphic includes all surveys done by NOAA’s Office of Coast Survey (and its predecessors), and some limited data acquired by other agencies, i.e., the U.S. Coast Guard. Areas that are not colored in have never been surveyed or have data acquired by another source — from Russia or Japan, for instance — before the U.S. was responsible for charting in that area.

Vintage of Alaska survey

What are the differences between data collected in 1900, 1940, or 1960? Let’s take a look at a…

Brief Historical Sketch of Survey Technologies

Nautical charts have a lot of information, but mariners especially are concerned with two major components: water depths (known as “soundings”) and obstructions (like underwater seamounts or wrecks).

Different eras used different technologies to find, measure, and determine the position of the two components. Note that adoption of new systems does not happen abruptly; rather, new technologies are phased in as techniques and equipment improves.

Measuring Water Depth (Soundings)

3.7 million years ago to present day: sounding pole

It isn’t inconceivable that the earliest humanoid, Australopithecus afarensis, used sticks to gauge water depths before crossing streams and rivers. People still do it today.

Egyptian use of sounding pole
Note the ancient Egyptian on the far right, using a sounding pole.

~ 2000 B.C. to 1930s: lead line

As good as they were for their eras, 19th and 20th century surveyors faced technological challenges. The first challenge was accounting for gaps between depth measurements. The second was the inability to be totally accurate in noting the position of the measurement. (In other words, a specific location out in the ocean may be 50 feet deep, but a surveyor must also accurately note the position of that specific location.)

Casting a lead line
This surveyor is casting a lead line.

Early Coast Survey hydrographers measured depths by lead lines — ropes with lead on one end — that were lowered into the water and read manually. Even though soundings were generally accurate, coverage between single soundings was lacking. And we need to remember that this was before the age of GPS. While sextants gave accurate positions when a hydrographer could fix on a shoreline feature, the further offshore the survey, the less accurate the position.

(Interesting fact: Hydrographers still use lead lines occasionally, in some circumstances — but not for a complete survey.)

There have been variations on lead lines through the centuries. From 1492 to the late 1870s, for instance, mariners used hemp rope for deep-sea soundings.

(Interesting fact: Christopher Columbus and Ferdinand Magellan each tried to measure mid-ocean depths with about 1,200 feet of hemp rope. Neither one of them found the sea bottom.)

In 1872, the hemp was replaced by small diameter piano wire (again, primarily for deep-sea work), and the weight of the lead was increased. Later, hydrographers added a motorized drum to wind and unwind the line, with a dial to record the length of the line.

(Interesting fact: In 1950, the British ship Challenger used piano wire in the first sounding that established Mariana Trench as the deepest place on earth.)

20th century to the present: echo sounders

comparison of survey technique coverage
Compare the bottom coverage achieved by the different survey methods.

1918 to 1990s: single beam echo sounder

Sonar came into its own in 1913. The first echo sounders (also known as “fathometers”) had single beams that measured the distance of the sea floor directly below a vessel. The echo sounders were able to take many more depth measurements than was possible with the lead line, but the technique still resulted in gaps between the lines where the beam measured the water depth.

The U.S. Coast and Geodetic Survey (a NOAA predecessor agency) adopted this acoustic sounding technique in 1923, installing it on USCGS Ship Guide. But full-fledged change didn’t happen right away. These early sounding systems were too large to install on survey launches used in harbor and inshore work, so from 1924 until the early 1940s many surveys were still conducted with a lead line, and many were totally acoustic — and some were hybrid, using soundings from both methods, depending on coverage area and seafloor configuration.

→ 1940: U.S. Coast and Geodetic Survey fully adopts single beam echo sounding technology

The development of smaller “portable” fathometers for shallow waters, about 1940, was a primary impetus in the obsolescence of lead line as survey technology and the adoption of acoustic systems. The development of World War II electronic navigation systems for bombing purposes led to the development in 1945 of the first survey-quality electronic navigation systems, which allowed for more accuracy in positioning.

1964 to current day: multibeam echo sounder

By mid-century, scientists were increasing the beams projected by the echo sounder, to get a broader swath of measurements. The multibeam echo sounder was developed for the Navy in 1964, but it remained secret until the late 1970s when commercially available systems were developed.

Coast Survey first used a MBES technique, called the “Bathymetric Swath Survey System,” in 1977 on NOAA Ship Davidson, for depths ranging from 160 to 2,000 feet. In 1980, NOAA Ship Surveyor installed a deep-water MBES system called “Sea Beam,” for depths from 1,600 to 33,000 feet.

About 1986, Coast Survey began using GPS to calibrate medium-frequency navigation systems while operating in the far reaches of the United States Exclusive Economic Zone. By the mid-1990s, GPS was the primary control for accurate positioning.

→ 2000: Coast Survey fully adopts multibeam surveying

By 2000, Coast Survey was performing full-coverage multibeam hydrographic surveys for charting purposes. NOAA survey ships now use multibeam echo sounders that measure navigable coastal depths from 45 to 1,000 feet. For shallower and more constricted waters, the ships deploy hydrographic survey launches with multibeam echo sounders that efficiently and safely survey areas from 12 to 200 feet deep. These systems make it possible to acquire 100% sea floor coverage in the survey grounds (excluding ultra-shallow, near-shore, or obstruction areas).

Finding Underwater Obstructions

1880s to early 1990s: wire drag

Surveyors used wire drag, not as a sounding system but as a way to look between the sounding lines to find obstructions to navigation and establish safe navigational channels. The first documented wire drag was conducted in the 1880s, in French Indochina, Gulf of Tonkin area, attaching the wire to buoys at each end and letting it drift with tidal currents.

Around 1900, the U. S. Lake Survey developed the technique of using a ¼-mile wire drag between two boats. In 1903, Coast Survey began using the technique, and within a few years was using it extensively in Alaskan waters as they looked for pinnacle rocks. Coast Survey’s Alaska wire drags were up to 3.5 miles long. (Initially, “least depths” over discovered obstructions were determined by lead line, then acoustic means and, ultimately, by divers with depth/pressure gauges.)

wire drag operations
Survey vessels conduct wire drag operations.

1960 to present day: side scan sonar

Side scan sonar is essentially the sonar equivalent of an aerial photograph. It improves the ability to identify submerged wrecks and obstructions. Evolving from submarine detection sonars of World War I and World War II, side scan sonar was fairly well developed by 1960, when the United Kingdom Hydrographic Office started using it regularly with their surveys.

→ 1990: Coast Survey fully adopts side scan sonar for East Coast and Gulf Coast surveys

NOAA Ship Whiting used the technology in 1984-1985 for approaches to New York. U.S. Coast Survey fully adopted side scan sonar (in place of wire drag) in the early 1990s.

lowering the tow fish for SSS
Side scan sonar operations use “towfish” like this one, lowered into the water and towed from the back of the vessel.
SSS image of wreck
Side scan sonar captures images of objects, which improves the ability to identify submerged objects.

Today’s Charts Reflect Different Tech Eras

Each of NOAA’s 1000-plus nautical charts, even today, can contain information collected by any or all of these sounding and positioning techniques.

Most nautical charts are an amalgamation of geospatial information collected using different techniques at different times. For example, one area of a specific current-day nautical chart might be based on a lead line and sextant survey conducted in 1910, and another area on the same chart might be based on a multibeam and GPS survey conducted in 2010. If we dig deep enough, we will probably find a sounding or two from the 18th century British explorer, Captain James Cook.

NOAA cartographers mold this disparate information so that it fits together as a coherent representation of the geographic area.

So when was the data acquired for the chart you’re using? NOAA cartographers add a “source diagram” to large-scale charts. (See the diagram on the current chart 16240, pictured below.) Check yours. That will give you the years of the surveys… and now you have a better idea on the technology used by the surveyor.

source diagram 16240
This is the source diagram on nautical chart 16240.

Coast Survey helps scientists sharpen hydrographic skills

By Lt.j.g. Eric Younkin

For four weeks in February, NOAA’s Office of Coast Survey offers formal hydrographic training to newly hired survey technicians and physical scientists, using the beautiful campus at the United States Coast Guard Training Center in Yorktown, Virginia. This year, dozens of NOAA employees and others took the extensive training, covering everything from acoustics and statistics to the processing of hydrographic survey data within the CARIS software package.

Two dozen people attended in person. They came from a wide range of duty assignments: NOAA ships Rainier, Fairweather, Thomas Jefferson, Pisces, and Oscar Dyson; Coast Survey’s R/V Bay Hydro II, Navigation Response Team 1, and the Atlantic Hydrographic Branch; NOAA’s National Geospatial Data Center; and the Washington State Energy Office. In addition, we had “virtual” attendance from the NOAA ships as well as from the Olympic Coast National Marine Sanctuary, the Integrated Ocean and Coastal Mapping Center, Washington State Energy Office, and United States Coast Guard District 17.

NOAA hydro class at USCG Training Center
NOAA Hydrographic Training course at U.S. Coast Guard Training Center Yorktown, Feb. 27, 2015. Photo by U.S. Coast Guard Auxiliarist Jonathan Roth.

During the last two weeks, we experienced a severe winter storm. The training facility and the surrounding roads and schools closed – but we still held classes, even though some of the commuting students had to join the ranks of the remote attendees.

POS MV demo
Training class participants enjoy a mobile demonstration of the POS MV.

First on the agenda, attendees received on-the-job training on board R/V Bay Hydro II, thanks to the officer-in-charge, Lt.j.g. Bart Buesseler, and physical scientist technician Rob Mowery. Students also set up a horizontal control base station, performed leveling runs, simulated shoreline feature acquisition and calibrated an Applanix POS MV system. Capt. Shep Smith, Lt. Cmdr. Olivia Hauser, Lt. Cmdr. Michael Gonsalves, physical scientist Glen Rice, and others offered their expertise on a variety of topics, including statistics and the organizational structure of Coast Survey.

Students learned about field operations and sonar theory, with classes offered by Lt. Megan Guberski from the NOAA Ship Thomas Jefferson, physical scientist Matt Wilson from Coast Survey’s Atlantic Hydrographic Branch, and physical scientist Mashkoor Malik from Coast Survey’s Hydrographic Systems and Technology Programs. Lt.j.g. Matthew Forrest from NOAA Ship Rainier, and Keith Brkich and David Wolcott from NOAA’s Center for Operational Oceanographic Products and Services covered vertical control and tidal theory.

We also appreciated the participation from CARIS’ Josh Mode and Tami Beduhn, as they explained the CARIS processing workflow.

To cap off the training, Rear Admiral Gerd Glang, director of Coast Survey, talked about the future of hydrography and – importantly – awarded training completion certificates to the students.

RDML Gerd Glang awarded training completion certificates. Here, Danielle Power receives her certificate. Photo by U.S. Coast Guard Auxiliarist Jonathan Roth.
RDML Gerd Glang awarded training completion certificates. Here, NOAA survey technician Danielle Power receives her certificate. Photo by U.S. Coast Guard Auxiliarist Jonathan Roth.

Coast Survey announces plans for 2015 NOAA survey projects

In 2015, NOAA survey ships Thomas Jefferson and Ferdinand R. Hassler are scheduled to survey nearly 1,800 square nautical miles in the U.S. coastal waters of the lower 48 states, collecting data that will update nautical charts for navigation and other uses. In Alaska, NOAA ships Fairweather and Rainier will increase their Arctic operations, planning to acquire 12,000 nautical miles of “trackline” depth measurements of the U.S. Coast Guard’s proposed shipping route. (See this NOAA article.) The ships will also conduct several “full bottom” hydrographic survey projects, acquiring data from over 2,800 square nautical miles in survey areas along the Alaskan coastline.

We are also planning several projects for our contractual private sector survey partners, and those projects will be announced after work orders are finalized.

The Office of Coast Survey will manage the surveys that measure water depths and collect ocean floor data for charting, identifying navigational hazards, informing wind farm decisions, mapping fish habitats, and assisting with coastal resilience. Check the useful story map, 2015 Hydrographic Survey projects, for the survey outlines and more information. Coast Survey will update the map as weather and operational constraints dictate.

2015 survey plan outlines
See the story map for all 2015 in-house projects.

Briefly, this year’s NOAA survey projects include:

1. Gulf of Maine, where chart soundings in heavily trafficked and fished areas are decades old and need updating for navigational safety

2. Buzzards Bay (Massachusetts and Rhode Island), where increased use of deeper-draft double-hull barges – and possible installation of marine transmission cable routes and wind energy development — requires updated soundings

3. Rhode Island Sound, where the Bureau of Ocean Energy Management has identified a wind energy lease area

4. Approaches to Chesapeake (North Carolina), where charts of critical navigational areas need updating for navigation and to assist the Bureau of Ocean Energy Management manage windfarm activity.

5. Approaches to Charleston (South Carolina), where updated soundings will provide the correct under-keel clearance information for the expected transit of larger and deeper-draft ships

6. Approaches to Savannah (Georgia), where the Savannah Harbor Expansion Project will increase the authorized depth of the harbor from 42 to 47 feet and updated soundings will provide the correct under-keel clearance information for the expected transit of larger and deeper-draft ships

7. Chatham Strait (Alaska), where charts need to be updated for cruise liners, ferries, Coast Guard cutters, Navy vessels, tugs, and barges that use this waterway on a regular basis or when avoiding storms in the Gulf of Alaska

8. Approaches to Kotzebue (Alaska), where deep-draft vessels have their cargo lightered to shore by shallow draft barges

9. Point Hope (Alaska), where shipping traffic is increasing due to receding ice but charted soundings are sparse and date back to the 1960s

10. West Prince of Wales Island (Alaska), where updated charts are needed by smaller vessels that use Televak Narrows as an alternate passage during foul weather

11. Shumagin Islands (Alaska), where Coast Survey needs data to create a new, larger scale, nautical chart

12. Port Clarence (Alaska), where Coast Survey needs data to create a new, larger scale, nautical chart

13. South Arctic Reconnaissance Route, where trackline data will assist consideration of the U.S. Coast Guard’s proposed Bering Strait Port Access Route Study

14. North Coast of Kodiak Island (Alaska), where we need to update charts for Kodiak’s large fishing fleet and increasing levels of passenger vessel traffic

NOAA Ship Thomas Jefferson celebrates survey success with maritime community

by Ensign Diane Perry, onboard NOAA Ship Thomas Jefferson

From 2005 through today, NOAA Ship Thomas Jefferson has been surveying Long Island Sound, one project area at a time. Some of the area was last surveyed between the late 1800s and 1939. For the 2014 field season, Thomas Jefferson was assigned her final Long Island Sound project, 89 square nautical miles of Eastern Long Island Sound, Fisher Island Sound, and Western Block Island Sound. When this project is complete, we will have resurveyed over 95% of Long Island Sound and all of Block Island Sound with modern survey technology that allows for a complete picture of the seafloor and highly accurate soundings.

This image depicts Thomas Jefferson's bathymetry from eastern Long Island Sound to Gardiner's Bay.
This image depicts Thomas Jefferson‘s bathymetry from eastern Long Island Sound to Gardiner’s Bay.

Data acquired by the Thomas Jefferson will update the region’s nautical charts and will serve other users within NOAA, the U.S. Geological Survey, and a New York and Connecticut Long Island Sound Seafloor mapping initiative. The mapping initiative creates products for habitat mapping and geological interpretation, and supports state planning and management of this vital resource.

Bringing the hydrography of this area into modern times has been a huge task, and we appreciate being welcomed as a part of the area’s maritime community! When Thomas Jefferson was asked to participate in the Connecticut Maritime Heritage Festival in New London this summer, the crew was excited for the opportunity to showcase the results of nearly a decade of surveying effort.

On September 12, Thomas Jefferson docked at City Pier, dressed in semaphore flags to welcome crowds lining the pier eager for guided tours. As the sun set, Thomas Jefferson hosted judges and the announcer during the festival’s lighted boat parade. The ship continued to provide tours the next day, and was the highlight of the event for many visitors. More than 500 visitors toured from fantail to bridge, learning about the ship’s mission and hydrographic survey operations, life at sea, and maritime heritage of NOAA and the Office of Coast Survey.

As the festival ended, Thomas Jefferson’s crew cast off from City Pier to return to their Long Island Sound working grounds and continue survey operations. We are excited to return to the survey area and complete the 2014 Long Island Sound mapping project.

NOAA Ship Thomas Jefferson
NOAA Ship Thomas Jefferson dressed in semaphore flags for Connecticut’s 2014 Maritime Heritage Festival. Photo by Lt. Cmdr. Abigail Winz.
LCDR Jim Crocker and Alex Ligon wrestle with wayward semaphore flags
Cmdr. James Crocker and hydrographic assistant survey technician Alex Ligon wrestle with wayward semaphore flags to keep NOAA Ship Thomas Jefferson looking her best for Connecticut’s 2014 Maritime Heritage Festival. Photo by Lt. Cmdr. Abigail Winz.
Lt. Guberski talks to tour group
Lt. Megan Guberski greets a tour group about to board NOAA Ship Thomas Jefferson during Connecticut’s 2014 Maritime Heritage Festival. American flags patriotically line New London train station in the background for the special event. Photo by Lt. Cmdr. Abigail Winz.
Photo of Guertin, Stone, Moulton, and Johnson
From left to right, “Teacher at Sea” Dr. Laura Guertin, hydrographic survey technician Allison Stone, Ensign Stephen Moulton, and general vessel assistant James Johnson dedicated their time to spreading the word about NOAA’s hydrographic mission.

NOAA R/V Bay Hydro II has a ball meeting the public in Baltimore!

Last week we blogged about Coast Survey’s research vessel Bay Hydro II, a small hydro research vessel that delivers big results. The vessel was heading into Baltimore Harbor for five days of public tours at Star Spangled Spectacular.

The Bay Hydro II crew and headquarters personnel had a great time with everyone — from the kids who learned about charts from an admiral, to the map geeks who enjoyed a discussion down in the hydro weeds. More than 4,000 people toured the Bay Hydro II during the celebration, and we hope they all learned at least a little about hydrographic surveying and nautical charts.

Rear Adm. Gerd Glang explains charts to kids
Rear Admiral Gerd Glang, director of NOAA’s Office of Coast Survey, introduced kids to nautical charts onboard R/V Bay Hydro II.
LTJG Bart Buesseler answers questions from the public
The Officer in Charge of R/V Bay Hydro II, Lt.j.g. Bart Buesseler, must have answered a million questions about surveying, charting, and serving in the NOAA Officer Corps.
Rob Mowery
Rob Mowery, the physical scientist who manages Bay Hydro II‘s surveys, called on his years of NOAA experience to explain hydrography to an inquiring public.
Tours pause for Blue Angels
Okay everyone, take a break! The Blue Angels are coming…