Sabrina Whitaker: Night Life, August 20-21, 2026

NOAA Teacher at Sea

Sabrina Whitaker

Aboard NOAA Ship Thomas Jefferson

August 18 – 31, 2026

Mission: Hydrographic Survey, Leg 3

Geographic Area of Cruise: Lake Ontario

Date: August 20-21, 2026

Weather Data from the Bridge

Latitude: 43°22.554’N

Longitude: 76°44.490’W

Winds: South-South East at 5 knots

Temperature:  60° F

Science and Technology Log

I spent the overnight shift with Hydrographic senior survey technician Emily Madish tonight. Her shift starts at 3:30 p.m. and goes until 3:30 a.m. She worked with two other crew members in the survey room: Operations Officer Jessie Spruill and Hydrographic Survey Tech Hannah Hernandez. There were more members of the crew on the deck navigating the ship through the dark waters. 

I took the opportunity of the quiet evening and having fewer people around to have Emily walk me through the process for collecting data on NOAA Ship Thomas Jefferson and to explain how the scientific equipment on the ship works to collect depth data. 

Hydrographic surveys make use of a variety of fundamental physics concepts. One of them is how sound travels. Sound travels at a constant speed through a medium (a material like water or air) unless the properties of the medium change. In lake or ocean water, properties that could change the speed are the salinity, temperature, and depth. Thomas Jefferson accounts for these possible changes by collecting that information using the Moving Vessel Profiler (MVP) and collecting that data approximately every hour so that the data collected by the ship can use the most accurate information to create the depth profiles. 

Once the speed of sound in the area has been collected, the time it takes for the sound to go to the bottom of the seafloor (or in this case lakebed) is collected. From there, the depth of the seafloor can be calculated using the equation:

To solve for depth, it becomes

However, the time included at this point includes both the time leaving the ship and going to the seafloor and back again, which can be visualized like this: 

To account for the reflection, the time that is collected is cut in half and the new equation becomes:

(Note: hydrographers use different letters to represent these variables, but I’m keeping everything in notation my high school students are or will be familiar with. They mean the same thing.)

Now, this seems relatively straight forward so far. However, what is really cool is that the ship is not taking just one sounding (depth measurement). Instead, the ship is sending out SONAR in a fan shape using a multibeam or side scan, which can be visualized as follows: 

This allows not only the various depths of the sea floor to be collected, but because many (MANY) soundings are taken at once, the soundings can also translate into images and an image of the seafloor can be created. In addition to an image of the seafloor, it is also possible to find out if there are any hazards to shipping or features on the seafloor. For example, in Lake Erie on the last leg of the mission a lot of shipwrecks were seen, and while there haven’t been any shipwrecks found on my leg as far I know, some features of the lakebed, like glacial scarring may have been seen, along with a lot of rocks. A lot of rocks. 

It is also possible to see schools of fish in the water column or capture an image of a whale with the multibeam or sidescan.

To get to the point of creating an image and having the image accurately represent the location of where the data was taken to create a meaningful map, while also correcting the data for errors and the motion of the ship requires many steps. 

First, the Seafloor Information System collects real time depth data being collected by the multibeam sonar, while HYSWEEP communicates with the bridge. Those in survey use HYPACK to make planned survey lines, and those on the bridge use HYSWEEP and follow those lines. The bridge and the survey team are in constant communication while this process is ongoing.

Thomas Jefferson travels back and forth like someone mowing their yard with long back and forth lines that overlap by about 20% to make sure that no areas are missed. 

The ship also collects what is called crosslines, which must be collected for every 4% or 8% of the lines collected that are parallel to each other, depending on the spacing between the lines, to make sure that the data remains reliable. It is possible the parallel lines could be offset from each other and the crosslines ensure that they are not. 

Once the data is collected, the data from GNSS including GPS and information from other satellites is collated with the ship’s depth data. This involves a lot of additional software that ensures the accuracy and fidelity of the information being collected. 

After everything has been processed, it is sent to NOAA for further integration into the maps that allow ships navigating the waters carrying people and goods across the Great Lakes stay safe. Progress on the Great Lakes project and other hydrographic survey projects can be found at: https://storymaps.arcgis.com/collections/855b7102bd0d42d6974c41fa4f8829b9?item=5

Personal Log

It’s fascinating to notice how life aboard the ship mirrors research experiences I’ve had elsewhere. During my undergraduate and graduate work, I spent night shifts at Brookhaven National Laboratory and Argonne National Laboratory running experiments at the synchrotrons. The late hours aboard the ship feel remarkably similar.

Night shifts have a distinct stillness. Instead of the busy daytime chatter and people moving about, the ship settles into a steady rhythm defined by the deep hum of instrumentation and running equipment. Monitors glow with data software, and as the end of the shift approaches, fatigue sets in—making it just a little easier to make a minor mistake (though usually the mistakes are fixable). Sometimes it even feels like the software itself gets tired of being up that late and starts acting up. But through it all, really cool data is collected despite anything else that happens.

Did You Know?

NOAA Ship Thomas Jefferson is sent out after natural disasters like hurricanes, to help ships enter and exit ports. The ship helps make certain that there are not any dangers to ships from the disaster, so that rescue, shipping, and reconstruction after the disaster can proceed.