NOAA Teacher at Sea
Jennifer Widdig
Aboard NOAA Ship Thomas Jefferson
June 17 – June 30, 2026
Mission: Hydrographic Survey
Geographic Area of Cruise: Lake Erie and Lake Ontario
Date: Monday, June 29, 2026
Weather Data from the Bridge
Latitude: 043o15’N
Longitude: 077o22’W
Sky Conditions: Sunny
Visibility: >10miles
Wind Speed: 1 knots
Dry Bulb: 19oC
Wet Bulb: 18.5oC
Science and Technology Log
One of the highlights of this leg was getting the opportunity to spend a day aboard survey launch 2904. Junior Officer Julian Santos served as our coxswain, while Senior Survey Technician Ali DiTommaso managed the survey equipment. It was a great opportunity to experience how NOAA conducts nearshore hydrographic surveys and to see firsthand the challenges of collecting data in shallow water.
Our mission for the day was to locate the 15-meter depth contour on our assigned survey sheet. Using the multibeam sonar, the display was configured so that anything shallower than 15 meters appeared black. As we “painted” the seafloor with the multibeam, we watched for that black boundary. Once we reached the 15-meter contour, we stopped collecting multibeam data in that area and moved on to find the next section of the contour. Eventually, we connected these sections to create a continuous 15-meter line across the sheet.
After establishing the contour, we switched to side-scan sonar to survey the area shallower than 15 meters. Because side-scan sonar can cover a much wider swath of the seafloor than the multibeam, our survey lines were spaced farther apart, allowing us to efficiently search for underwater features and potential hazards. During our survey we operated the 75-meter side-scan system in water depths ranging from approximately 7 to 15 meters. We did not have the opportunity to switch to the 50-meter side-scan configuration, which is typically used in even shallower water, from about 4 to 8 meters.
Working from a small survey launch requires constant multitasking. Since it was the weekend, recreational boat traffic was heavy, requiring extra vigilance while navigating and collecting data. Unlike aboard the ship, the launch crew must solve many equipment issues on their own or troubleshoot with assistance over the phone. At one point, our air conditioning stopped working. Although it certainly made for a warm day, it did not affect the safety of the operation, so we continued surveying.
Although the surveying stops when the launch returns to the ship, the work is far from over. Every evening, the survey data is processed so it can be evaluated before the next day’s operations. During this process, the survey technicians apply the sound velocity information collected from the Sea-Bird CTD casts. Because sound travels at different speeds depending on the water’s temperature, salinity, and pressure, these measurements are essential for accurately calculating the depth of the seafloor.
The data is also corrected using the vessel’s position, motion, and orientation throughout the survey. Every pitch, roll, heave, and heading change of the launch is accounted for so the seafloor is mapped in its true position rather than being distorted by the boat’s movement. Water level corrections are also applied to account for changes in lake level during the survey.
Once these corrections have been made, the software combines the overlapping survey lines and “smooths” the edges between them to create a continuous, high-quality map of the seafloor. Processing also helps identify any holidays, small gaps where little or no data was collected. If holidays or other data quality issues are found, the area will need to be resurveyed before the sheet can be considered complete.
Personal Log
Going out on a survey launch was one of the highlights of my time aboard NOAA Ship Thomas Jefferson. I already love being out on the water, so I knew my biggest challenge wouldn’t be seasickness but trying not to be rocked to sleep! The water was calm, with waves less than a foot high, something the crew was very thankful for, even if I secretly wouldn’t have minded a little more excitement.
After boarding 2904, we were lowered over the side of the ship. I followed Senior Survey Technician Ali DiTommaso onto the bow, where she released the locking clamps that connected us to the davit. It was fascinating to watch how smoothly the process worked and to finally experience a launch from the small boat perspective.
We spent the day on the water from about 6:30 a.m. until 3:30 p.m. The launch may be much smaller than the ship, but it is surprisingly well equipped. We brought water, hot water for tea, breakfast, and snacks, and there was even a small refrigerator stocked with sandwich supplies and a microwave for lunch. It felt like a tiny floating office.
With Junior Officer Julian Santos serving as coxswain and Ali running the survey operations, I jokingly felt like the “passenger princess” for the day. While they handled the work, I had the opportunity to observe every aspect of the survey. Seeing hydrography on a smaller scale helped me better understand the process.
One of the most impressive moments came at the end of the day during recovery. Watching the coxswain carefully maneuver alongside the TJ looked effortless, but I quickly realized how much coordination is required. The engineers stand by in case there are any issues with the davit or the launch, the Bosun operates the davit, crew handle the lines, and the entire evolution is supervised by the Commanding Officer and Executive Officer. Meanwhile, the bridge monitors everything from the bridge wing to ensure the recovery is completed safely and efficiently.
Before I had the chance to ride on one of the launches, I had watched them return to the ship from the deck. Seeing the boats racing across the water toward the TJ with spray flying behind them reminded me of something straight out of an old James Bond movie. They looked fast, powerful, and just a little dramatic. It felt like they were in slow motion!
Santos and Ali really made the day great, and I was lucky enough to get to tag along with them!
Did You Know?
- The Great Lakes span 4,530 miles of coast and account for 21% of the world’s freshwater, with more that 30 million people relying on them for drinking water.
- The nautical term “holiday” comes from the 17th century when missing a spot while painting a ship. “Were you on a holiday?” or “Do you need a holiday?”