NOAA ship Fairweather on the mission to map large swaths of the Bering Sea

A stunning 61 percent of Alaskan maritime waters are not sufficiently mapped by modern standards, and a much higher percentage in the vast Bering Sea and Bering Strait region  is not up to date in modern charts, either. This, coupled with increasing ship traffic made possible by decreasing sea ice in the Bering Strait region, is a potential recipe for ship accidents. However, the National Oceanic and Atmospheric Administration vessel Fairweather, has been in and out of Nome this summer – and years past — to conduct hydrographic surveys to update nautical charts to improve maritime safety.
Out of the 15 ships in the NOAA fleet, four are dedicated to hydrographic survey missions, and only two of those are on the West Coast. One of them is the NOAA ship Fairweather. This summer, the ship is on a mission to map the coastline around St. Matthew Island, continue mapping a route through the Bering Sea, Bering Strait and north to the Beaufort Sea, and assist a scientific mooring mission.

Mapping priorities
The Office of Coast Survey sets mapping priorities, explains the Commanding Officer of NOAA ship Fairweather, Commander Damian Manda. “They analyze generally what the chart quality is in different areas, and they prioritize based on things like vessel traffic, what size that vessel traffic is, if there’s increases in that traffic,” he said in an interview aboard the Fairweather last week. “Areas like the Bering Sea and the Arctic are becoming increasingly important because there’s more traffic, there’s larger traffic— when we get these tankers and cargo ships taking the Northern Sea Route. And there’s now cruise ships. They’re also going down to St. Matthew Island, where we’re mapping.”
The Office of Coast Survey prioritizes when they see either incidents, such as a fishing vessel running aground near St. Matthew, or increases in traffic, or if an area that has never been mapped but sees a fair amount of commercial interest or traffic going through it.

Of Sonar and weather
Fairweather uses a multibeam sonar to map the seafloor and check for hazards. Much of the seafloor has been mapped before, but with older, out-of-date technologies. In a room aboard, filled with computers, screens and a map table in the center, Commander Manda leans over a printout of a map of St. Matthew Island. In the corner, the printout shows a chart of the island dated from 1951, the last time the area was surveyed. He explained the process of mapping near shore waters that can be tricky due to wave action and the navigational hazards they try to put on the charts.
When mapping those shallower waters, the ship deploys launches. It carries four launches that each come with their own multibeam sonar mapping equipment and are crewed with three to four people.
As conditions need to be fairly calm to get a good read of the seafloor, the weather often is the deciding factor of the mapping progress. “We can only operate the ship up to about six-foot waves, and the launches up to maybe about three or four, and even that’s kind of pushing it,” Manda said. “In general, the weather is one of our main limiting factors.”
Their cruises are dictated by weather patterns. Fairweather is homeported at Ketchikan and started their 2026 missions in March and April in Southeast Alaska, then moved on to Kodiak Island. As the ice receded in June, they crossed the Bering Sea, went to work at St. Matthew Island and came to Nome to resupply and change crews. This week, the Fairweather will attempt to continue the mapping of the Arctic Port Access Route Study, or PARS, route before going on servicing arctic moorings and then returning to Kodiak by the end of September.

The PARS shipping lane
The U.S. Coast Guard conducted the Arctic Port Access Route study, resulting in a proposed  shipping lane. “They’ve completed a study of this area, and they’ve established where they want the traffic lane to be, and then they send in us to go in and map it,” said Fairweather Operations Officer, Lieutenant Alice Beittel.
Last year, Fairweather mapped the route into the Chukchi Sea. The PARS route is about four miles wide, stretching from the Bering Sea, through the Bering Strait and into the Beaufort Sea.
The ship uses a multibeam sonar that measures the seafloor from the bottom of the ship in a triangle shape. 
Much of the Bering Sea is very shallow, between 40 and 50 meters in depth. This means that the ship can only map about a 200-meter swath of seabed at a time, requiring many passes to cover a four-mile-wide lane.
For the bathymetric data to be accurate, the ship uses precise positioning systems to track the movement of the ship in the water which is refined further during post-survey processing.
Alongside the sonar data, the ship also has a moving vessel profiler, or MVP, which can be towed behind the ship. The MVP takes a snapshot of the water column, providing data about the temperature, pressure and salinity, three important values for calculating the speed of sound underwater. In the Arctic, ice melt will change the salinity of the water and impact sound speed. “There’s all these different changes that happen to the chemical properties of the water column, and so that influences sound speed,” said Beittel. “We need to know how the speed of sound is changing at every interval through the water column to be able to accurately describe the depth.”
“The final product that we produce is this bathymetric surface, so just the topography of the seafloor,” Commander Manda said.  “A report that accompanies that says all the methods that were used and explains any issues that might be there.” Additional observations are added to the report. 
A contract vessel, the Wolstadt, is operating in Norton Sound for hydrographic surveys planned and tasked by NOAA Office of Coast Survey, the same office that provides tasking for Fairweather.
Once the data is collected, it can take up to two years to be processed and be used in the coastal navigation charts. Any significant dangers to navigation are fast-tracked to publication on electronic charts. This happens as soon as the danger is found, and is why it is important to mariners to frequently update their electronic charts.
Much of the Bering Strait region’s seafloor is fairly stable. Once mapped, the areas will likely not need to be resurveyed for many years, Manda said.
But there are areas where the seafloor changes fast and dramatically. In late May, the Fairweather collaborated with the U.S. Coast Guard Buoy Tender Cypress to revitalize Bechevin Bay, a channel to the east of Unimak Island that connects the Pacific Ocean to the Bering Sea. The seabed in the area already has dramatic changes year to year, and sea ice this winter took out crucial navigation markers, which marked safe passage through the shallow and narrow channel. “We worked with our small boats over the course of a few days to identify where the most recent channel is,” said Beittel. “The anchors of the buoys are these big concrete blocks, and so we were looking for any hazards in the channel, and to identify any sunken buoys and blocks.”
The Fairweather turned over their maps of the depths  and the Cypress was able to replace all the buoys throughout the whole channel. The waterway was open just in time for the June 1 commercial fishing season opener.

Collaboration
The data collected isn’t just used for building the topographic maps of the seafloor. Manda described it as “map once, use many times.” In addition to hazards mapped with sonar, the ship also notes down other maritime features such as kelp beds, marine wildlife congregations, breakers, high tidal currents – and those are available in the fully finished chart. “We try to make our data as useful to as many different parts of the NOAA enterprise, and also other organizations that can build off of it,” he said.
The ship’s work relies on cooperation with local communities. The Office of Coast Survey’s navigation manager serves as a liaison between the public and surveyors. Locals often have hyper-specific knowledge that can help the Fairweather in their mission. “She’ll talk to fishermen, she’ll talk to the tug and barge operators. She’ll talk to the local communities and learn about their priorities,” said Manda.
The navigation manager is also the liaison with Indigenous communities. Keeping in contact with those communities lets the locals express concerns. “Often those are areas where they’re going to be conducting whaling or other operations, fishing,” said Manda. Areas to be avoided or speed limits, those requests are respected, said Manda. 
Nome is important to the operation of the Fairweather. It is the only port the ship can call on across the entire western coast of Alaska, making it essential for resupplying, crew rotations and medical emergencies. The ship bought seafood from the Norton Sound Seafood Plant and purchased fuel from Bonanza. The ship also takes on water from the port and offloads their sewage, using a local company.
While at sea, the ship has a desalination plant that supplies the ship with fresh water.
The expansion of the Port of Nome will help provide a more protected area to dock. Currently, Commander Manda said, “If there’s any kind of weather coming in from the south, the ship can’t stay at the dock.”
The Fairweather is the only NOAA survey ship that routinely spends the winter in Alaska, as it is home ported in Ketchikan. Many of the crew are starting to set down roots in Alaska. The professional mariners on the ship are rotated in shifts, three months on, two months off. During operations, there are between 40 to 45 crew, with the full roster being around 70 employees.
Next for  Fairweather is a collaborative project with NOAA’s Pacific Marine Environmental Lab and Global Ocean Monitoring and Observing Program to service biophysical moorings in the Arctic.  “Our job will be to help them recover the ones that are out there right now, turn over the instruments, get new instruments down there with fresh batteries,” said Beittel.
NOAA Ship Fairweather is next scheduled to be in Nome the first week of September.