NOAA Ship Rainier recently arrived in Uganik Bay, off of northwest Kodiak Island, to complete hydrographic survey operations in Uganik Passage and Uganik Bay, including the Northeast Arm, North Arm, and South Arm. Rainier has spent 2013 through 2016 surveying areas around North Kodiak Island, including Kizhuyak Bay, Whale and Afognak Passes, Kupreanof Strait, and Viekoda and Terror Bays. The ship will remain in Uganik Bay until the end of October.
Rainier is using multibeam sonar technology to acquire high-resolution seafloor mapping data to provide modern chart updates that support Kodiak’s large fishing fleet and higher volumes of passenger vessel traffic. Some of the data appearing on NOAA’s charts in this area are from surveys conducted between 1900 and 1939. (See the source diagram in the bottom left corner of NOAA chart 16597.) However, this is not Rainier’s first visit to Uganik Bay. In the early 1970s, Rainier was in the same vicinity performing survey operations and installing survey stations at Broken Point, Uganik Bay, and Shelikhof Strait.
Commissioned in 1968, NOAA Ship Rainier has a 48-year history in NOAA’s fleet of research ships and aircraft. Homeported at NOAA’s Marine Operations Center-Pacific in Newport, Oregon, she is operated and managed by NOAA’s Office of Marine and Aviation Operations. The 231-foot Rainier is one of four hydrographic survey ships in the NOAA fleet that support the nautical charting mission of NOAA’s Office of Coast Survey to keep mariners safe and maritime commerce flowing. The ship, her four aluminum survey launches, and other small boats collect data that is used to update nautical charts and inform decisions on coastal science and management.
Each of Rainier’s small boat launches has modern sonar systems that gather data nearshore as well as offshore. Additionally, the ship itself has a sonar system mounted to her hull for offshore operations. This information can provide bottom seafloor habitat characterization for sustainable fisheries initiatives, and provide data for ocean tourism and recreational fishing.
If you happen to be in the area, and see a white hull with S-221 painted on her bow, please do not hesitate to contact the ship to acquire more information regarding the ship and her mission. Rainier monitors VHF channels 13 and 16. Or, email Rainier’s public affairs officer at email@example.com.
In a unique deployment of resources, last week NOAA Ship Fairweather split its scientific team and vessels to tackle two distinct projects in Alaska. Coast Survey physical scientist Katrina Wyllie and Lt.j.g. Bart Buesseler report on the multi-mission projects.
On August 9, NOAA Ship Fairweather departed Dutch Harbor, Alaska, for a FISHPAC project, led by Dr. Bob McConnaughey from NOAA’s Alaska Fisheries Science Center. This project’s primary mission is to statistically associate acoustic backscatter returns with the abundances of fish and crabs that frequent the Bering Sea seafloor. The science team accomplishes this with acoustic data from multibeam, single beam, and side scan sonars. Understanding the value of acoustic backscatter as a habitat-defining character will help scientists understand where fish live and the importance of different habitats. The acoustic data will also be used to correct for differences in the performance of research bottom trawls on different seafloor types, so that stock assessments and fishery management can be improved. To make sure the scientists understand what the acoustic data are showing, each day the ship will stop and collect physical bottom samples of the seafloor to see, touch, and interpret their findings. Further increasing the effectiveness of this mission, all of the multibeam bathymetry data acquired will directly support NOAA’s Office of Coast Survey as the data will be used to update soundings on the nautical charts for the eastern Bering Sea where the ship will be operating.
With Fairweather actively conducting 24-hour ship survey operations in Bristol Bay, there wouldn’t be any chance to deploy her four survey launches for additional acquisition. Sensing an opportunity, the Office of Coast Survey, the command of the Fairweather, and Marine Operations Center-Pacific collaboratively came up with a multi-mission plan to maximize the capabilities of Fairweather during the FISHPAC project. Before departing Dutch Harbor, Fairweather deployed a shore team with the four survey launches to stay in Dutch Harbor and address some critical navigation needs identified by the port.
Although its location is remote, the port of Dutch Harbor is a vibrant and bustling port serving full-size container ships. It is the country’s top fishing port in terms of landings for the past 18 years. Deep draft and ice-free year-round, Dutch Harbor provides a critical link in America’s transportation infrastructure. Trivia buffs may also know that Dutch Harbor is the only other American soil, in addition to Pearl Harbor, to be bombed during World War II. (For more on Alaska in World War II, see USC&GS Ship Hydrographer contributes to significant Allied victory.)
With the increase in commerce flowing into and out of the harbor, local maritime pilots asked Coast Survey navigation manager Lt. Timothy Smith for updated nautical charts to improve the safety of maritime traffic. This need was underscored in July 2015, when a polar ice class vessel ran aground in an area of the chart which hadn’t been surveyed since before World War II. Shortly after this grounding, Fairweather was able to alter their schedule to conduct a response survey in the area of the grounding (green area in project sheet layout, below). Additionally, Fairweather had previously surveyed small high priority areas in 2011 (orange areas).
This month’s collaborative project, performed in conjunction with FISHPAC, provided the perfect opportunity to address these navigational needs. With the survey launches remaining in Dutch Harbor, with a team of scientists, coxswains, and engineers to support them, Fairweather’s shore team will acquire complete coverage multibeam data in the entire project area, totaling approximately 38 square nautical miles, as outlined by the blue shapes in the project sheet layout.
The City of Unalaska has graciously facilitated this unique mission by providing pier space for all four launches for the project’s duration. The team itself has established a base of operations at the Grand Aleutian Hotel, where they have converted a conference room into a command center to process the day’s freshly collected data, while preparing the mission for the subsequent day.
The shore team has plenty of work to keep them busy until August 27, when Fairweather returns to Dutch Harbor after completing the more than 4,000 line-mile FISHPAC mission and recovers the survey team and launches. Fairweather then transits back to Kodiak, Alaska, for a scheduled inport and well deserved break before hydrographic survey operations resume in the vicinity of Sitkalidak Strait.
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.
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.
~ 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.)
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
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.
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.)
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.
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.
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.
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
In preparation for the M/V TERN’s anticipated arrival this week in San Francisco Bay, the Coast Guard and Port of San Francisco asked Coast Survey for a bathymetric survey of the proposed anchorage site. TERN is a semi-submersible vessel with a 60-foot draft, and the proposed anchorage site has charted depths of 62 feet and 63 feet ‒ leaving no room for error, to say the least. The question was whether there are any spots shoaler than 62 feet.
This isn’t your everyday anchorage.
“This vessel floods ballast tanks and partially sinks, putting the main deck below water. Items can then be floated onto the ship, and then water is pumped out of the ballast tanks to bring the main deck back above water level,” explains Lt. Michael Davidson, chief of Coast Survey’s Navigation Response Branch. “TERN won’t actually be anchoring in the anchorage, but rather will be held in place with tugs while cranes are transferred. When she submerges during the operation, her submerged depth is 60 feet.”
Coast Survey assigned Navigation Response Team 6 to investigate the depths with its multibeam echo sounder, to ensure that the TERN will have the under keel clearance she needs. Last week, as requested by the Coast Guard, NRT 6 conducted an investigative survey around Whiskey 2, Anchorage 9. (Whiskey 2, depicted on the survey chart as W2, is a “bucket” that resides within Anchorage 9. A bucket is where they usually park a ship.) Of the many small, pocked features, the team found six that exhibit a height above bottom. Most notable of these features is a 60’ shoalest sounding near a 63’ charted depth – near the location where TERN was supposed to submerge.
After the Coast Guard received the team’s report of obstructions, they asked Coast Survey to investigate an additional area. They were looking for a spot that was at least 62′ deep, free of any features.
“In our area of survey near W1, there were no features that exhibited a height above bottom or showed any significant scour,” reports Ian Colvert, acting team lead of Coast Survey’s Navigation Response Team 6. “The area near W1 is a much more promising place to park the TERN, versus W2 which had a few features and depths not as deep.”
Coast Survey has a proud 200-year history of protecting ships from accidents. NRT6 gives us a very real example of how that mission continues today.
This summer, the Bering Sea Alliance hosted a private-public summit in Gambell, Alaska, to discuss Arctic resource development and infrastructure. (See page 10 in this edition of the Nome Nugget for a good summary of the meeting.) Lt. Tim Smith, NOAA Coast Survey’s regional manager for Alaska, updated the participants on the status of Arctic nautical charts and described NOAA’s Arctic Nautical Charting Plan. He also outlined the preliminary 2015 survey plans to acquire hydrographic data around Point Hope, Point Barrow, Port Clarence, and Kotzebue Sound, as NOAA strives to ensure the navigational safety of the increasing ship traffic through Arctic waters.
In addition to his role as navigation manager and NOAA Corps officer, Lt. Smith is one of NOAA’s best photographers. His photos of the area around Gambell are better than words in conveying the beauty of this remote area of Alaska.
With the photo below, Tim reminds us that black and white photos can sometimes reveal more than full color.
NOAA Ship Rainier recently surveyed Whale Passage, which separates Whale Island from Kodiak Island, Alaska. The area has never been surveyed with modern full bottom coverage methods, and some project areas were last surveyed by lead lines around a hundred years ago. The area frequently experiences 7 knot currents, making rocky or shoal areas particularly treacherous. Whale Passage is a high traffic area for fishing vessels, U.S. Coast Guard cutters, barges, ferries, and small boats, which is why updating the area’s nautical charts is so important.
The dynamics of the passage and surrounding area create several challenges for the hydrographic survey teams. The local tidal and current models are not well-known. To resolve this, Rainier was instructed to install four tide gauges in the greater project area, compared to a typical requirement for one gauge. Two of these gauges are a mere 4.5 nautical miles apart, in and just outside of Whale Passage itself. Some areas are so narrow and experience such high currents that it is only possible to survey in one direction in order to maintain control of the launch. The coxswain must plan each turn carefully, to avoid being pushed into dangerous areas. Ideally, these areas would be surveyed at or near slack tide. However, the slack in this survey area is incredibly brief and the predicted slack periods did not match what survey crews saw in the field.
The bathymetry is so dynamic that, even in relatively deep water, boat crews must remain alert for rocks and shoals. The survey teams found several large rocks in locations significantly different from where they were charted. Furthermore, the presence of large kelp beds increases the difficulty of surveying: they can foul the propellers on the launches, add noise to the sonar data, and can also obscure the presence of rocks.
While the work within Whale Passage, and the neighboring Afognak Strait on the north side of Whale Island, is challenging, it is also high-value. In addition to correcting the positions of known rocks and hazards, Rainier and her crew found a sunken vessel. Most importantly, though, they found areas that were charted twice as deep as they actually are. When the chart reads 8 fathoms (48 feet) and the actual depth is only 4 fathoms (24 feet), commercial traffic utilizing the passage could be in serious danger of running aground. Thus far, Rainier has submitted two DTON (danger to navigation) reports for depths significantly shoaler than charted. These new depths are already published on the latest version of chart 16594.
NOAA Ship Rainier will continue to survey the vicinity of Whale Passage, as well as the waters near Cold Bay out in the Alaskan Peninsula, for the remainder of the survey season before heading home to Newport, Oregon.