The Crystal Serenity, a 250-metre-long luxury cruise ship, arrived in Nome, Alaska, on 22 August 2016 to a citywide commemoration. This scheduled stop was part of the ship’s historic voyage through the fabled Northwest Passage.
Along with other business leaders, Fugro was represented at the event. “The Crystal Serenity’s voyage through the Northwest Passage is a striking example of both the opportunities and needs associated with a newly accessible Arctic,” said David Millar who manages Fugro’s hydrographic survey business in the United States.
Accurate and up-to-date charts are an essential tool for navigation, providing mariners with information about the shoreline, seafloor characteristics and navigational aids. In 2013, the Arctic Council working group for the Protection of the Marine Environment estimated that only six-to-seven percent of the Arctic contains nautical charts meeting international navigational standards.
The sheer volume of this charting backlog is further complicated by operational and economic factors, including short field seasons lasting just two to four months; remote locations with little or no infrastructure; and limited governmental resources.
Given these circumstances, Fugro is working with hydrographic program managers to streamline the nautical chart making process. The approach involves integrating multiple technologies and platforms, namely vessel based multibeam echosounder and airborne LiDAR bathymetry.
Developed in the 1980s, the multibeam echosounder is the most common technology used to acquire nautical charting data. Working from a survey vessel, the system operates underwater to emit acoustic energy pulses over a broad swath for full survey coverage and seabed esonification.
Fugro has performed multibeam surveys all over the world, including the Arctic. While multibeam is an ideal technology for surveying water depths greater than 20-30 metres deep, in shallower waters efficiency suffers. The multibeam collection swath narrows the closer the system gets to the seafloor, requiring increased survey lines that produce less survey coverage. Additionally, manoeuvring vessels in shallow, uncharted water can be slow due to unknown shoals and other potential dangers.
To efficiently fill the gap between the nearshore and the shore and to survey the shore itself, Fugro performs airborne LiDAR bathymetric surveys. Developed in the 1990s, this technique utilises light rather than sound, and operates from an aircraft rather than a vessel. Laser energy from the sensor’s infrared band is used to detect the water surface, while energy in the green band penetrates into the water to map the seafloor. The difference between these two measurements provides water depth.
Faster, Safer Nautical Charting
Fugro’s phased, multi-technology approach to optimise Arctic charting efforts balances coverage with accuracy and resolution over shallow water and coastal areas. Navigational hazards made available from the LiDAR coverage also help vessel crew plan the deeper multibeam missions with increased efficiency and decreased risk.
“In collaboration with one of our customers, we tested this methodology in an uncharted area of the Canadian Arctic in 2012,” Millar explained. “A survey that had been estimated to take five years to complete using only vessel-based techniques was successfully charted in just one year.” Final data products also exceeded the client’s charting data requirements, comprising a continuous bathymetric data layer covering the entire seafloor and intertidal zone and maintaining a consistent transition to elevation data above the high water mark.
“Working with clients to develop new techniques for streamlined delivery of critical data in the Arctic is a top goal for Fugro in the region,” Millar stated. “Currently, we are collaborating with another customer to see if and how satellite derived bathymetry can be brought into the mix for further time and cost savings.”