NOAA Teacher at Sea
Aboard NOAA Ship Thomas Jefferson
June 25, 2018 – July 6, 2018
Mission: Hydrographic Survey- Approaches to Houston
Geographic Area of Cruise: Gulf of Mexico
Date: July 3, 2018
Weather Data from the Bridge
Latitude: 29° 17.5’ N
Longitude: 094° 27.7’ W
Visibility: 10+ NM
Sky Condition: 3/8
Wind: 10 kts
Sea Water: 29.5° C
Air: 31.1° C
Science and Technology Log
In the beginning, it took me a little while to realize that we were passing by some of the same oil platforms and seeing the same ships on the radar screen (above). For example, today the Thomas Jefferson covered many nautical miles within the same 2.5 NM area. This is characteristic of a hydrographic survey. A sheet (area to be surveyed) is split into sections and a plan is devised for the ship to cover (using sonar) the area in a “mow the lawn” approach. In the photo below, you can see the blue lines clustered together. These are the main scheme lines and provide the majority of data. The lines going perpendicular in a loose “zig-zag” to the main scheme lines are called crosslines. While main scheme provides the majority of sonar data, crosslines provide validation. For every 100 nautical miles of main scheme, 4 NM of cross lines (4%) must be completed.
You can also see the main scheme and crossline(s) in the Hypack viewer below. Hypack is a software program controlled from the Plot (Survey) Room and is duplicated on a screen on the Bridge (steering deck). This allows Bridge watch standers to see track lines and the desired line azimuth (direction). In this case the line azimuth is around 314°. Additionally, the bottom portion showing -0.0 means that the ship is precisely on track (no cross-track errors). Typically, during a survey from the main ship, there is room for up to 10 meters of error in either direction and the sonar data coverage will still be complete. Once the course is set, the ship can be driven in autopilot and manually steered when making a turn. The high-tech equipment allows the rudder to correct and maintain the desired course and minimize cross-track error. Still, at least two people are always on the bridge: an officer who makes the steering orders and maintains watch and a helmsman who steers the ship. I was fortunate to be able to make two cross line turns after a ship steering lesson from AB (able seaman) Tom Bascom who has been on ships his whole life.
At night, the ship is put into “night mode” and all lights are switched to red. The windows are covered with a protective tinted sheet and all computer screens switch over. The CO leaves a journal with posted Night Orders. These include important summary points from the day and things to look out for at night It also includes a reminder to complete hourly security rounds since most shipmates are asleep. A “Rules of the Road” section is included which serves as a daily quiz for officers. My favorite part of CO’s Night Orders are the riddles, but they are quite difficult and easy to over think. So far, I have guessed one out of five correctly.
With a lot of my time spent looking at computer screens in survey, I was happy to spend an afternoon outside with the Deck Crew. Their job is highly diverse. Rob Bayliss, boatswain group leader, explained that the crew is responsible for maintaining the deck and ship. This includes an ongoing battle with rust, priming, painting, and refinishing surfaces. Rob wiped his hand along the rail and showed the massive amount of salt crystals collected throughout the day. The crew has a PR event and will give public tours the day we arrive in port, so the ship is in full preparation!
I also spoke with Chief Boatswain, Bernard Pooser. He (along with many crew members) have extensive experience in the navy. Pooser enjoys life on the ship but says, “It’s not for everyone; you have to make it work for you.” He claims that the trick is to find a work and recreation balance while on the ship. He gave me some examples like being sure to take breaks and have fun. Pooser even pulled out a corn hole set that we may use one of these evenings.
+ It’s been fun being on the bridge at night because all of the ships and platforms light up.
+ I was given my own stateroom which was nicely furnished by its usual occupant. She has even installed a hammock chair!
+I hadn’t realized how responsive the ship would be when steering. At 208 feet, I thought it would be a bit more delayed. The maximum turn angle is 35 degrees and we have usually been making turns around between 5-15 degrees.
+We saw two sea turtles and dolphins while taking bottom samples! (See future post.)