NOAA Teacher at Sea
Jennifer Widdig
Aboard NOAA Ship Thomas Jefferson
June 17 â June 30, 2026
Mission: Hydrographic Survey
Geographic Area of Cruise: Lake Erie and Lake Ontario
Date: Friday, June 26, 2026
Weather Data from the Bridge
Latitude: 043o20′ N
Longitude: 077o18′ W
Sky Conditions: Cloudy
Visibility: 9 miles
Wind Speed: 9 knots
Wind Direction: W
Dry Bulb: 18oC
Web Bulb: 18oC
Science and Technology Log
Surveying has finally begun! Before any data can be collected with the multibeam sonar system, the survey technicians first deploy a Sea-Bird CTD (Conductivity, Temperature, and Depth) instrument. This important piece of equipment measures the water’s conductivity, temperature, and depth throughout the water column.
Why is this necessary? The multibeam sonar determines water depth by sending sound waves to the lake bottom and measuring how long it takes for the echoes to return. However, sound does not travel at the same speed through all water. Changes in temperature, especially at the thermocline where warmer surface water meets colder deeper water, can significantly affect sound velocity. If these variations are not accounted for, the depth measurements could be inaccurate.
Once the Sea-Bird CTD has been recovered, the survey technicians move to the acquisition station to begin collecting hydrographic data. This is where the real mapping of the lake floor begins.
At the acquisition station, technicians have access to navigation information through HYSWEEP, a software program that displays the planned survey lines and the vessel’s position in real time. Because the survey team and bridge officers are looking at the same information, technicians can communicate precise directions to help keep the vessel on the correct track lines.
The team collects crosslines across each survey sheet. These lines provide an initial overview of the seafloor terrain and later serve as an important quality-control check. By comparing the crossline data to the primary survey lines, technicians can verify the accuracy of their measurements.
Another key display is the Seafloor Information System (SIS), which shows the depth data being collected by the multibeam sonar. As the vessel travels back and forth along carefully planned survey lines, the sonar data appears on the screen like strokes from a paintbrush. Each pass adds another strip of seafloor information until the entire survey sheet has been âpaintedâ with depth measurements.
The survey vessel must travel in straight, parallel lines because the data collected during turns is often unreliable. When the ship turns, turbulence and bubbles form beneath the hull. These bubbles interfere with the sonar signals, preventing them from reaching the bottom and returning accurate depth measurements. On the data display, these disruptions appear as black streaks or gaps, similar to those shown below.
During this leg of the mission, the NOAA Ship Thomas Jefferson was finally able to deploy both of its survey launches. This marked the first time this season that both small boats could be used, following repairs to a broken DAVIT cable that had previously limited operations.
Before any launch leaves the ship, the survey team gathers to complete a Float Plan, brief and conduct an Operational Risk Management assessment using a GAR (Green, Amber, Red) score. This process evaluates factors such as weather, crew readiness, equipment status, and mission complexity to determine whether it is safe to proceed.
Once approved, the launches are deployed using the ship’s davit system. The davit lifts the boat over the ship’s rail, and after it is safely positioned, the launch crew boards. The davit then carefully lowers the boat into the water where it begins survey operations.
The survey launches play a critical role in hydrographic mapping. Each boat is equipped with multibeam sonar and side-scan sonar systems that allow surveyors to collect detailed seafloor data in areas too shallow for the ship to safely navigate. By working close to shore and in confined areas, the launches help ensure complete coverage of the survey sheets and provide valuable information for updating nautical charts and identifying potential hazards to navigation.
Because the 2903 launch had not been deployed yet this season, the crew encountered several issues that needed to be addressed during their launch. To tackle these challenges, the Commanding Officer (CO), Executive Officer (XO), engineers, Operations Officers, survey technicians, and available officers gathered for a debrief to discuss solutions and develop a plan moving forward.
One aspect that I found particularly interesting was learning how replacement parts are obtained while the ship is underway. When a needed part is not available onboard, it is often shipped to the nearest port. The crew then evaluates the ship’s schedule, available transportation options, and operational priorities to determine the most efficient way to retrieve it. What might seem like a simple repair on land requires careful coordination and planning at sea.
These debriefs serve another important purpose as well. In addition to troubleshooting equipment issues, they allow the team to review the day’s operations, assess progress, and develop a detailed plan for overnight activities and the following day’s survey work. It was another reminder of the amount of teamwork, communication, and problem-solving required to keep a hydrographic survey mission running successfully.
Personal Log
It has been really rewarding to take part in more activities on board. Iâve had the opportunity to deploy the Sea-bird CTD and assist with both the launching and recovery of the small boats, which has given me a much better appreciation for how coordinated and precise these operations need to be and how many hands are needed. Thank you to Chief Scientist Sarah Thompson and Bosun Alex Bischoff for the opportunities to help out along side them. Iâve also really enjoyed observing the work on the bridge and seeing how navigation, communication, and decision-making all come together in real time to keep operations running safely and efficiently.
One of the biggest adjustments for me has definitely been the 4:30 p.m. dinner time! Eating three full meals between the hours of 7am and 4:30pm is slowly killing me, but it is SO hard to skip a meal when everything is so good. Iâve also been surprised by how cool the temperatures have been while on board which has been really nice. I have spent most of the time in pants and light sweaters.
My photo was also added to the crew board, which made me feel even more like part of the team and included in the daily life of the ship. Overall, being exposed to so many different roles and responsibilities on board has been eye-opening. If I had known earlier about the range of careers involved in hydrography and ship operations, I absolutely would have considered this path when I was younger.
Did You Know?
Ports are not required to maintain current depth information for their slips, which can increase the risk of vessels running aground. Can you see the dock in the background we are backing in to in Osewgo?
