NOAA Ship Fairweather uses new technology to improve survey efficiency

By ENS Peter Siegenthaler

Following the scheduled winter repair period, Fairweather is kicking off the 2017 field season in Tlevak Strait; the waterway between Dall Island and Prince of Wales Island in Southeast Alaska. This area was last surveyed between 1900 and 1939, and the lead-lines used at the time to determine depths were susceptible to omission of rocks and other features in an area. Using the latest innovations in hydrographic technology, Fairweather will be resurveying these areas with complete coverage multibeam echo sounder bathymetry. This allows Fairweather to identify any rocks or shoal features missed in prior surveys, increasing the safety for local communities, whose economies and livelihoods are dependent on maritime transportation of goods.

One of the new developments Fairweather’s survey department in particular is excited about is a new software program affectionately named “Charlene.” Charlene was developed by PS Eric Younkin at Coast Survey’s Hydrographic Systems and Technologies Branch (HSTB) to automate the night processing workflow. This simplifies hours spent each night converting and correcting raw sonar data into an automated script which takes in raw data at one end and generates products at the other. Initial results are promising, and the ship is looking forward to fully integrating Charlene into the processing workflow.

Another new development for the 2017 field season is new multibeam sonars for the ship’s survey launches, which were installed during the winter repair period. The preliminary data acquired by these sonars has shown vast improvement over their predecessors’ data, which will go a long way towards reducing data processing timelines. The new sonars do this by automating most of the acquisition parameters in real-time, far faster and more effectively than could be achieved manually. They also take advantage of a multitude of hardware and software advances that have taken place over the past several years, resulting in systems that are quieter, smaller, and easier to operate.

Fairweather is continuing to use and develop the launch-mounted lidar systems (lasers) for the acquisition of shoreline data. This was another HSTB-developed process that was validated during the 2016 field season. This year, Fairweather is using those lessons learned in order to further improve our acquisition workflow. These systems create accurate real-time point clouds of features above the waterline and have revolutionized the way hazards to navigation are documented. Before the use of lasers, shoreline verification frequently required physically touching rocks and obstructions above the water surface for accurate measurement and placement. This process involved increased risk, took more time, and produced less accurate data. The new laser workflow addresses all these limitations. By scanning the shoreline at a distance with calibrated equipment, efficiency, accuracy, and safety are all greatly improved.

Overall, Fairweather is enthusiastic about being back at work in Alaska. With her new software, sonar systems, and dedicated crew, the stage is set for and productive field season!

Area surveyed by Fairweather May 30- June 10, 2017.
Area surveyed by Fairweather May 30- June 10, 2017.

NOAA survey ships adopt laser scanners to improve safety at sea

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].”

laser image of NOAA ships
Laser image of NOAA Ships Fairweather, Rainier, and Shimada moored at Marine Operations Center – Pacific, acquired during training

 

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.

Features on chart 16604
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 finder to 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.
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.