Hayden Roberts: Playing Hide and Seek with Sonar, July 16, 2019

NOAA Teacher at Sea

Hayden Roberts

Aboard NOAA Ship Oregon II

July 8-19, 2019


Mission: Leg III of SEAMAP Summer Groundfish Survey
Geographic Area of Cruise: Gulf of Mexico
Date: July 16, 2019

Weather Data from the Bridge
Latitude: 28.51° N
Longitude: 84.40° W
Wave Height: 1 foot
Wind Speed: 6 knots
Wind Direction: 115
Visibility: 10 nm
Air Temperature: 30.8°C
Barometric Pressure: 1021 mb
Sky: Clear


Science Log

In my previous blog, I mentioned the challenges of doing survey work on the eastern side of the Gulf near Florida. I also mentioned the use of a probe to scan the sea floor in advance of trawling for fish samples. That probe is called the EdgeTech 4125 Side Scan Sonar. Since it plays a major role in the scientific research we have completed, I wanted to focus on it a bit more in this blog. Using a scanner such as this for a groundfish survey in the Gulf by NOAA is not typical. This system was added as a precaution in advance of trawling due to the uneven nature of the Gulf floor off the Florida Coast, which is not as much of a problem the further west one goes in the Gulf. Scanners such as these have been useful on other NOAA and marine conservation research cruises especially working to map and assess reefs in the Gulf.

deploying side scan
Preparing to put the side scan over board.

Having seen the side scanner used at a dozen different research stations on this cruise, I wanted to learn more about capabilities of this scientific instrument. From the manufacturer’s information, I have learned that it was designed for search and recovery and shallow water surveys. The side scanner provides higher resolution imagery. While the imagining sent to our computer monitors have been mostly sand and rock, one researcher in our crew said he has seen tanks, washing machines, and other junk clearly on the monitors during other research cruises.

This means that the side scanner provides fast survey results, but the accuracy of the results becomes the challenge. While EdgeTech praises the accuracy of its own technology, we have learned that accurate readings of data on the monitor can be more taxing. Certainly, the side scanner is great for defining large items or structures on the sea floor, but in areas where the contour of the floor is more subtle, picking out distinctions on the monitor can be harder to discern. On some scans, we have found the surface of the sea floor to be generally sandy and suitable for trawling, but then on another scan with similar data results, chunks of coral and rock have impeded our trawls and damaged the net.

Side scan readout
Sample scan from monitor in the computer lab. The light areas are sandy bottom. The dark is either seaweed or other plant material or rocks. The challenge is telling the difference.


Did You Know?

In 1906, American naval architect Lewis Nixon invented the first sonar-like listening device to detect icebergs. During World War I, a need to detect submarines increased interest in sonar. French physicist Paul Langévin constructed the first sonar set to detect submarines in 1915. Today, sonar has evolved into more sophisticated forms of digital imaging multibeam technology and side scan sonar (see https://oceanexplorer.noaa.gov/explorations/lewis_clark01/background/seafloormapping/seafloormapping.html for more information).


Personal Log

When I first arrived aboard Oregon II, the new environment was striking. I have never spent a significant amount of time on a trawling vessel or a research ship. Looking around, I took many pictures of the various features with an eye on the architectural elements of the ship. One of the most common fixtures throughout the vessel are posted signs. Lamented signs and stickers can be found all over the ship. At first, I was amused at the volume and redundancy, but then I realized that this ship is a communal space. Throughout the year, various individuals work and dwell on this vessel. The signs serve to direct and try to create consistency in the overall operation of the ship and the experience people have aboard it. Some call the ship “home” for extended periods of time such as most of the operational crew. Others, mostly those who are part of the science party, use the vessel for weeks at a time intermittently. Before I was allowed join the science party, I was required to complete an orientation. That orientation aligns with policies of NOAA and the expectation aboard Oregon II of its crew. From the training, I primarily learned that the most important policy is safety, which interestingly is emblazoned on the front of the ship just below the bridge.

Safety First!
Safety First!

The signs seem to be reflective of past experiences on the ship. Signs are not only reminders of important policies and protocols, but also remembrances of challenges confronted during past cruises. Like the additional equipment that has been added to Oregon II since its commission in 1967, the added signs illustrate the history the vessel has endured through hundreds of excursions.

Oregon II 1967
Bureau of Commercial Fisheries Ship Oregon II (1967), which was later transferred to NOAA when the administration was formed in 1970.
Oregon II 2017
NOAA Ship Oregon II in 2017 on its 50th Anniversary.

Examples of that history is latent in the location and wording of signs. Posted across from me in the computer lab are three instructional signs: “Do not mark or alter hard hats,” “Keep clear of sightglass do not secure gear to sightglass” (a sightglass is an oil gauge), and “(Notice) scientist are to clear freezers out after every survey.”

signs collage
A collage of four signs around NOAA Ship Oregon II
more signs
Another collage of four signs around NOAA Ship Oregon II
even more signs
Another collage of signs around NOAA Ship Oregon II

Author and journalist Daniel Pink talks about the importance of signs in our daily lives. His most recent work has focused on the emotional intelligence associated with signs. Emotional intelligence refers to the way we handle interpersonal relationships judiciously and empathetically. He is all about the way signs are crafted and displayed, but signs should also be thought of in relation to how informative and symbolic they can be within the environment we exist. While the information is usually direct, the symbolism comes from the way we interpret the overall context of the signs in relation to or role they play in that environment.