USVs for NOAA’s Shoaler-depth Nautical Chart Surveys

On U.S. coastal nautical charts, the areas closest to the shore, shoals and rocks generally do not have updated depth measurements. In many areas, safety concerns prohibit the use of NOAA ships or launches to survey the shoalest depths. Charting those shallow areas is about to get safer, thanks to recent purchases of small, commercial off-the-shelf, unmanned survey vessels (USVs). This summer, NOAA Ship Thomas Jefferson is deploying a Z-Boat offered by Teledyne Oceanscience.

Aside from the reduced depth in these areas making them unavailable for a survey vessel, in many areas the water is too murky to be mapped with the airborne Lidar systems used in clear waters.

Complementing

The Z-Boat complements the ship’s existing hydrographic toolkit. Thomas Jefferson uses her multibeam echosounder to measure depths from 45 to 1,000 feet. For shallower and more constricted waters, the ship’s two hydrographic survey launches with multibeam echosounders efficiently and safely survey areas from 12 to 200 feet deep. The Z-Boat (using a singlebeam echosounder) facilitates Thomas Jefferson to measure depths in areas as shallow as one foot, and get that data into processing almost immediately. The boats are highly manoeuvrable, turning in their own 5.5-foot length, meaning they can get much closer to piers, pilings and the shoreline than a full-sized launch.

This new capability is important to improving charts for smaller vessels operating near the coast, and in the inlets, bays, and harbours so critical to many small coastal towns. In the 1930s, the Roosevelt Administration – through its massive Depression-era public works programme – hired hundreds of men to survey shallow Intracoastal Waterway areas. Since then, NOAA has done very little survey work in shallow water, causing a backlog of reported shoals, rocks, wrecks and obstructions in shallow water. Knowing the depth in these inlets is also important to accurately predicting coastal inundation during storms.

Thomas Jefferson, with the support of NOAA’s Office of Marine and Aviation Operations’ innovative platform programme, is using two Z-Boats this summer in Massachusetts to investigate shoals and rocks in Buzzard’s Bay and Vineyard Sound. This December, they will use them in a project near Chesapeake Bay.

Quickly Operational

One of the benefits of using off-the-shelf vehicles like Z-Boats is that hydrographers are able to calibrate the boats and put them into use quickly, without the need for additional installation and integration of a survey system. Thomas Jefferson took delivery of the boats on 13 August 2015. They now have qualified the system for hydrographic use, developed first-generation deployment and retrieval systems, and trained a cadre of Z-Boat ‘pilots’.

Thomas Jefferson will operate the boats from a control station on the ship or one of their launches. Depending on the circumstances, technicians have several options to control the boats, by using: 1) a handheld remote control; 2) a networked radio link with one-mile range; or 3) an onboard autonomy module. NOAA is working with Teledyne and with researchers at the University of New Hampshire-NOAA Joint Hydrography Center to develop improvements to the boat’s autonomy system that will permit it to gradually work more independently of the operator. With more Z-Boat autonomy, survey ships can operate a larger fleet of boats without adding additional operators.

Autonomous Working with Manned Systems

NOAA envisions unmanned and autonomous systems working in conjunction with the manned systems, deployed and controlled from hydrographic survey ships. The Z-Boats are the first step towards unmanned surface vessels. Lessons learned are to drive further innovation in communications and automation technology.

Thomas Jefferson will be exploring other options for the boats. For instance, Z-Boats have an onboard streaming video camera, so the operator can see what the boat ‘sees’ in real time, raising the possibility of additional uses beyond depth measurements. And although these Z-Boats are fitted with singlebeam echosounders appropriate to very shallow water, there is an option to fit them with sidescan sonar, or a multibeam system, for other applications.

Image: Lt. Joseph Carrier, operations officer on NOAA Ship Thomas Jefferson, deploys a Z-Boat from the ship. Image courtesy: NOAA.