David Tourtellot: The Speed of Sound, July 15, 2018

NOAA Teacher at Sea

David Tourtellot

Aboard NOAA Ship Thomas Jefferson

July 9-26, 2018

Mission:  Hydrographic Survey – Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 15th, 2018

Weather Data from the Bridge

Latitude: 28° 49.4115’N

Longitude: 93° 37.4893’W

Visibility: 10+ Nautical Miles

Sky Condition: 4/8

Wind: Direction: 240°, Speed: 7 knots

Temperature:

Seawater: 31.7°C

Air: Dry bulb:31.5°C          Wet bulb: 27.5°C

 

Science and Technology Log

 

NOAA Ship Thomas Jefferson is well underway in its mission of surveying the seafloor. The primary tool that the ship (as well as its 2 Hydrographic Survey Launches) is using to accomplish this task is sonar. Sonar was originally an acronym for SOund Navigation And Ranging. If you are familiar with echolocation – the system that some animals (such as bats and dolphins) use to navigate their surroundings – then you already have a basic understanding of how sonar works. The sonar transmits a short sound (called a ping) that will travel down, away from the ship, until it hits the seafloor. At this point, it will reflect off of the sea floor, and echo back up to the ship, where it is detected by the sonar’s receiver. The crew aboard are then able to calculate the depth of the water.

To make the necessary calculations, there are 3 variables at play: the time that it takes for the ping to travel; the distance that the ping travels; and the velocity, or the speed, at which the ping moves through the water. If we know two of those variables, it is easy to calculate the third.

When using sonar to determine the depth of the water, distance is the unknown variable – that’s what we’re ultimately trying to figure out. To do so, we need to know the other two variables. Time is an easy variable for the sonar to measure. The sonar has a transmitter, which generates the ping, and a receiver, which hears it. These two components communicate with one another to give us an accurate measure of time. The third variable, velocity, is a bit trickier.

In saltwater, sound travels approximately 1500 meters per second. However, that rate can vary slightly based on water conditions such as temperature and salinity (how salty the water is). In order for sonar to get as accurate a reading as possible, it needs to calculate the precise speed of sound for the particular water it is in at the moment. The sonar is able to do that by using a component called a sound velocity sensor, known colloquially as a singaround.

Sonar 1 Singaround

The sonar on the hull of one of the Hydrographic Survey Launches. The orange rectangles are the projector (or, the transmitter) and the receiver, and the component in the green circle is the singaround

A singaround looks like a bar with a nub on each end. One nub is a projector, and the other is a reflector. The projector broadcasts a ping that travels parallel to the hull of the ship, bounces off of the reflector, and returns to the projector. We use that information to calculate velocity. The calculation uses the same 3 variables as above (time, distance, and velocity), but this time, distance isn’t the unknown variable anymore – we know exactly how far the ping has traveled, because we know how far the projector and reflector are from one another. The singaround electronically measures how long it takes for the ping to travel, and since we now know two of the variables (distance and time) we can calculate the third (velocity) for our particular water conditions at the face of the sonar.

Sound travels roughly 4 times faster in water than it does in air (this is because water is denser than air). To ensure that the sonar gets an accurate reading, it is important that air bubbles don’t get in the way. The boat’s hull (bottom) has a triangular metal plate directly in front of the sonar, which routes air bubbles around to the side of the sonar.

Sonar 2

The hull of one of the Hydrographic Survey Launches.

 

Personal Log

Each day, the ship’s CO (Commanding Officer) publishes a POD, or Plan Of the Day. This is full of important information – it tells us what the ship will be doing; if/when we will deploy the launch boats, and who will be on them; what time meals will be; and the expected weather conditions. Below is an example from Friday, July 13th.

Plan of the Day

NOAA Ship Thomas Jefferson Plan of the Day for Friday, July 13, 2018

On Friday, I had the opportunity to go out on one of the Hydrographic Survey Launches. Because of their smaller size, the launch boats are great for surveying difficult to maneuver areas. For instance, we spent most of the day surveying an area near an oil rig, and were able to get much closer than the Thomas Jefferson could.

Mike Below Deck

Survey Tech Mike Hewlett collecting and analyzing survey data aboard a launch boat

Oil Rig and Boat

An oil rig and a supply vessel

I’ve been very impressed by how multi-talented everyone on the ship seems to be. In addition to analyzing data, the ship’s survey techs can also be found handling lines as the survey boats are launched and recovered, and do a lot of troubleshooting of the hardware and software they’re using. The coxswains (people who drive small boats) double as engineers, fixing issues on the launch vessels when away from the ship. I’m surrounded by some very gifted people!

Fixing the AC

Coxswain Francine Grains and Survey Tech Brennan Walters fixing the air conditioner on one of the launch boats that had stopped working unexpectedly. They had it up and running in no time

Did you know?: As president, Thomas Jefferson ordered the first survey of the coastline of the United States. Because of this, NOAA Ship Thomas Jefferson is named for him. 

Latest Highlight: While surveying, we spotted a water spout in the distance. A water spout is a tornado that forms over water. Luckily, we were a safe distance away. It was an amazing sight to see!

 

Brandy Hill: First Leg (hopefully not the last!) at Sea Complete: July 12, 2018

NOAA Teacher at Sea

Brandy Hill

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 12, 2018

 

Personal Conclusion

It was wonderfully impressive listening to ENS Jacquelyn Putnam’s orders to the Bridge while docking the ship. She and Lt. Klemm stood just outside the doors to the Bridge with a clear view of the dock at Pier 21. As she called out orders, the Bridge team would respond by making adjustments to the rudder, speed, or direction. I hadn’t realized how much of a team effort docking the ship would be. It was like parallel parking a car in busy downtown Portland on a much larger scale.

FishingVessel.jpg

We arrived at Pier 21 in Galveston, Texas early Friday morning on July 6th. There were several fishing vessels flocked with birds. Sometimes you could see dolphin fins peeking up through the water around the boat.

After we were safely docked, all shipmates met in the mess where CDR Chris van Westendorp gave a speech of recognition and appreciation for his crew. These last couple legs at sea are especially meaningful for CO as they symbolize a transition of many years at sea to an upcoming land assignment. There were also several people taking much-deserved leave, or moving onto other job assignments.

 

 

SunsetBow.jpg

Sunset from the bow during my two weeks aboard NOAA ship Thomas Jefferson.

I am so grateful to have been able to participate as a teacher at sea on the Thomas Jefferson. I knew it would be a learning experience, but I didn’t realize how impactful my relationships and interactions with the crew would be. There is something truly inspirational about being around a well-functioning team of people serving a meaningful purpose. People are excited to work for NOAA and to be a part of a higher scientific mission.

I also hadn’t realized the direct relationship between hydrographic surveys and hurricane relief. After a hurricane, the sea floor can shift and change/block major pathways for delivering supplies like oil and water. Last year, NOAA ship Thomas Jefferson responded to Hurricane Maria in Puerto Rico,  “NOAA Ship Thomas Jefferson spent the last three weeks in Puerto Rico and the U.S. Virgin Islands surveying ports and bays in response to Hurricane Maria. Over the three week period, the crew surveyed 13 areas and no fewer than 18 individual port facilities, as well as conducted emergency repairs to three tide and weather stations.” (NOAA Office of Coast Survey, October 2017)

Looking towards next school year, I am excited to bring my experience into the classroom and provide students with meaningful learning opportunities. I am looking into using Citizen Science, ways of incorporating the Ocean Literacy Principles, and reaching out to have more diverse professionals interact with my classroom. One of my goals as a science and math teacher is to provide students with many opportunities to ask questions, explore, think critically, and be inspired to continue a lifelong journey of learning and growth.

My experience with NOAA and NOAA ship Thomas Jefferson will forever have an impact on my classroom and for that, I am extremely grateful.

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4th of July goodies made by ENS Sydney Catoire, Julia Wallace, and Kevin Brown.

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I practiced my Bowline knots on the long trek home.

David Tourtellot: Out To Sea and Gathering Data, July 11th, 2018

NOAA Teacher at Sea

David Tourtellot

Aboard NOAA Ship Thomas Jefferson

July 9-26, 2018

Mission:  Hydrographic Survey – Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 11, 2018

Weather Data from the Bridge

Latitude: 28° 51.29’N.

Longitude: 093° 44.54’W

Visibility: 10+ Nautical Miles

Sky Condition: 6/8

Wind: Direction: 285°, Speed: 4 knots

Temperature:

Seawater: 30° C

Air: Dry bulb: 30.1°C  Wet bulb: 26.8°C

 

Science and Technology Log

NOAA Ship Thomas Jefferson is currently anchored in the Gulf of Mexico, approximately 50 miles Southeast of Galveston, Texas. The ship is on a hydrographic mission, meaning it is in the process of mapping an approximately 1100 square nautical mile area in order to make updated nautical charts. These will be very useful for ships as they approach the Port of Houston, which is one of the busiest ports in the world.

NOAA Ship Thomas Jefferson carries 2 smaller  survey vessels (also known as Hydrographic Survey Launches, or HSL’s) that assist in our research. These boats carry sonar systems (which I will go into greater detail about in a future blog post), as well as some other devices that are used to make various measurements. I was fortunate enough to be able to go out on one of these smaller boats as they collected a variety of data.

NSTJ and Smaller Boat

One of the small survey boats near NOAA Ship Thomas Jefferson

One device that is used is called a CTD. The name is an acronym, standing for conductivity, temperature, and depth. Conductivity refers to how well the water conducts electricity. That data can be used to determine the salinity of the seawater, or how salty it is. If a scientist knows the salinity and temperature of the water, they can determine the density of the seawater.

Kevin with CTD

Kevin Brown putting a CTD into the water

Additionally, the boats carry devices that collect samples of the sea floor. The makeup of the seafloor varies greatly from one location to another – some areas are sandy, while others are rocky or muddy. This information can give mariners a better idea of what the underwater habitat is like, and is some of the most sought after data that NOAA Ship Thomas Jefferson is collecting.

Bottom Sample July 10th

Mud collected from the sea floor

The bottom sample that we collected was mostly mud. In addition to recovering a physical sample, the crew is experimenting with taking a photo of the seafloor using a GoPro camera. When I was on board, they had successfully mounted the camera to the bottom sampler, but were unable to get a good image.

 

Personal Log

Thomas Jefferson in Galveston

Port side view of NOAA Ship Thomas Jefferson docked in Galveston, TX, where I got on board.

I arrived in Galveston, TX, on the morning of July 8th, which was a Sunday. I found the ship to be mostly empty, as most of the crew had gone into the city. I was greeted by ENS Garrison Grant, who gave me a tour of the ship. The ship left port on Monday afternoon, and it was fascinating watching the crew on the bridge navigate out into open water. The lanes going into Galveston and Houston were very busy with a wide variety of vessels – I saw everything from small fishing boats to huge container ships and cruise ships. Safe navigation requires clear communication and lots of attention to detail. I imagine that it could be quite stressful, but the bridge crew were all calm and professional.

Yesterday, we did two safety drills – the first was a fire drill, and the second was an abandon ship drill. The general principles of these drills are very similar to what we do at school – we make sure that every individual knows where they are supposed to be and what role they are supposed to play in an emergency situation. Hopefully we won’t need to put that knowledge to use, but practicing these procedures is essential to crew safety in the event of an emergency.

Me in survival suit

In the event that the crew needs to abandon ship, all of us will don survival suits before going to the life raft.

 

I’m delighted to say that I have found the crew to be very friendly and helpful – they’re very patient with me and good at explaining their complex systems in easy to understand terms, for which I am very grateful.

Before I left Missouri to join the ship, my friends, students, and colleagues asked me dozens of questions, but probably the most frequent one was about the living arrangements on board. I didn’t know what to expect, and I have found the stateroom I’ve been assigned to be quite pleasant. The room is equipped with a comfortable bunk bed, a small television, a refrigerator, and an en-suite bathroom. There are also a pair of desks and ample storage room.

Stateroom

The stateroom I am staying in while aboard the ship

Did you know?: When measuring the temperature of the air, NOAA Ship Thomas Jefferson uses both a dry bulb thermometer and a wet bulb thermometer. The difference between the two allows us to determine the relative humidity of the air.

Highlight of the Day: Yesterday, while aboard the small boat, I saw several dolphins playing in the water. I’ve never seen dolphins in person before, so it was really cool getting to watch them.

David Tourtellot: Introduction, July 5th, 2018

NOAA Teacher at Sea

David Tourtellot

Aboard NOAA Ship Thomas Jefferson

July 9-26, 2018

Mission:  Hydrographic Survey – Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 5, 2018

 

Personal Introduction: Greetings! My name is David Tourtellot, and in just a few days I will be joining the crew of NOAA Ship Thomas Jefferson as part of the Teacher At Sea program. I feel very fortunate having been chosen for this opportunity, and I couldn’t be more excited!

I received a degree in Music Education from the Conservatory of Music and Dance at the University of Missouri – Kansas City, and I just finished my fifth year teaching 5th and 6th grade orchestra classes at 4 elementary schools in Lee’s Summit, Missouri. We had a great year making music together!

Tourtellot Headshot Close

David Tourtellot

I have long been fascinated by the field of acoustics, and I share that with my students. Not only do they learn the fundamentals of playing music, we also discuss how their instruments make sound, the properties that make one instrument sound different from another, and why our ensemble sounds different performing in one room than we do in another. Currently, NOAA Ship Thomas Jefferson is doing a hydrographic survey and is using sonar (which operates using sound waves) to detect what is underwater. I am very much looking forward to learning more about this, and helping my students to make deeper connections between science and the arts.

IMG_1734

At the National Weather Service Forecast Office in Pleasant Hill, Missouri

I’m also looking forward to spending time on the ship. I’ve lived my entire life in the Midwest, and can count the number of boats I’ve been on on one hand. This will certainly be a new experience!

Brandy Hill: Weather Reports and Rock Hunting, July 5, 2018

NOAA Teacher at Sea

Brandy Hill

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 5, 2018

 

Weather Data from the Bridge

Latitude: 28° 53.4’ N

Longitude: 093° 44.6’ W

Visibility: 10+ NM

Sky Condition: 3/8 (Reminder: 3 out of 8 parts of the sky are covered with clouds.)

Wind: 6 kts

Temperature:

Sea Water: 29.1° C

Air: 27° C

 

Science and Technology Log

It is fitting to add a section on weather because tonight we are seeing a lightning storm! I can even hear the fog horn. During Bridge Watch, weather data is logged every hour around the clock. Every four hours, it is entered into a computer system. On most days, we are fortunate to get a weather report in various character voices over the intercom from ENS Krabiel.

DeckLogWeatherObs.jpg

This is the hourly weather log from June 26, 2018.

My favorite tools are the wind wheel, alidade, and relative humidity thermometers.

WindWheel.jpg

A somewhat complicated process allows one to find the true direction (opposed to relative) of the wind. Since the ship is not always traveling North, it is important to be able to calculate true wind direction. Officers typically use a reading on the computer to find true wind direction, but I thought it was a neat tool to try.

Alidade.jpg

The alidade is located outside of the Bridge. It is a sighting device used for measuring angles. It has been helpful with measuring the swell direction. ENS Krabiel mentioned that it is also useful for checking bearings when a ship is anchored. For example, a bearing (like to an oil platform in the Gulf of Mexico) will change if the ship is drifting and/or dragging anchor.

RelativeHumidity.jpg

On the Weather Log, there is a place for “dry bulb” and “wet bulb.” This information is collected using two thermometers outside of the Bridge. The dry bulb is a typical thermometer, while the wet bulb has a small sock-like covering wicking up water from a tray. The closer the two temperature values, the higher relative humidity.

I have also sat in on a number of data processing evenings with the Survey Team. In one evening, roughly 50 GB of data from multibeam sonar only was processed. It is estimated that a total of 11 TB has been processed since April. Data processing begins around 7:30 pm and the survey team analyzes all information collected during the hours of 7am- 7pm. Staying on top of processing is important because of the massive amounts that accumulate, especially from side scan sonar.

Julia Wallace, physical scientist, showed me one aspect of processing multibeam sonar. She takes a file of data and runs a “flier finder” with a parameter of 0.5 meters (appropriate for the depth of sonar.) Essentially, the flier finder is marking any outliers that fall outside of this range. Julia then manually goes through and “hides” these points so that they do not contribute to the data set. This is important because when this data is used to mark bathymetry (sea floor depth) on nautical charts, it will somewhat randomly “grab” these false sounding set numbers and could land on one of the outliers, resulting in a false depth.

SonarPings.jpg

Every dot in this picture of raw data is a sonar ping returning to the multibeam echosounder. The number of pings depends on the sonar sounding frequency. For example, one could expect 300 pings per second when operating at a sounding frequency of 300 hz.

From what I have witnessed and gathered through multiple conversations with the team, the data collected by the Thomas Jefferson for NOAA charts is extremely accurate. For example, every pixel (or node) on the multibeam sonar grid represents no coarser than 1 square meter of the sea floor. This has changed from about 30 years ago where the ratio was 1 nodel: 5 square meters. In addition, many processes are doubled-up as a check for validity. This includes crosslines for checking main scheme data and operating two multibeam frequencies at the same time.

Backscatter.jpg

One of the benefits to running two frequencies of multibeam is the ability to create an overlapped average of the two backscatter signals (with a false color scheme.) This information helped inform Lt. Anthony Klemm and survey technician Kevin Brown determine eight unique sites varying in backscatter intensity for bottom sampling. (Remember: intensity is a measure of how strong the sonar ping returns, depicting varying sea floor substrate.

The use of this technology paid off! All eight sites sampled varied in texture and sediment size. Using this process of selectively choosing sites of interest based on “multispectral” backscatter intensity has replaced taking numerous random bottom samples using a grid. Again, this is a highly accurate and time-saving process. It was also interesting seeing the actual sea floor that we are mapping.

BottomSampleLocation.jpg

In the bottom right corner, Bottom Sample #1 site is selected.

 

 

 CHST Allison Stone manages the crane while Lt. Charles Wisotzsky directs the bottom sample claw and ENS Taylor Krabiel performs various substrate tests. 

TopView.BottomSamples.jpg

ENS Krabiel gives me a tutorial on bottom sampling. Krabiel enjoys creating short “Rock Hunting” clips for entertainment. His enthusiasm has made this trip a lot of fun.

BottomSampleShells.jpg

All of the eight bottom sample sites had a different composition. One in particular had a lot of rocks and shells. The rock in the upper right appears to have remnant tunicate casings.

BottomSampleNotes.jpg

Notes from survey sheet H13044, BS# 001 (Bottom Sample #1) state the grain size: silt, muddy, coarse, and some shell fragments.

A GoPro is located in a cage on the bottom sample claw. Video footage of the sea floor enables hydrographers to view the substrate and current ripples in the sand. ENS Krabiel wears the control on his wrist to activate the camera.

Personal Log

 I have enjoyed hearing the back-stories of the crew. For example, Allison Stone, Chief Survey Technician knew she wanted to be a part of NOAA when she was in 6th grade- the same age as my students. She remembers going to a parent career night at school and speaking with a presenter from NOAA. The presenter was enthusiastic about their job which inspired Allison to pursue a placement with NOAA. Although she envisioned counting marine animals and snorkeling daily, she is still passionate about her work in hydrography geoscience and speaks highly of NOAA outreach.

Field Operations Officer, Lt. Anthony Klemm started out wanting to do a public service and became a teacher. Later, he joined the NOAA Corps and after completing basic training got a job at the Marine Chart Division in Washington DC. It was during this time that he was given a lot of flexibility and time to create and test his own ideas and experiments. In his words, some of them flopped. However, one idea that has recently captured attention is the idea of “crowdsourcing” bathymetry. Collecting, processing, and submitting data for the official approval and update of NOAA nautical charts is a long process. It can take months for charts to be updated and available to the public. Crowdsourcing bathymetry is a way for the general public to gather and submit sonar data using simple devices like a “fish finder” that one might find on a recreational boat. These could serve as interim bathymetry data until the areas can officially be surveyed and charted. It’s also simple (users select a setting), and free.

Visit the NCEI/IHO Data Center for Digital Bathymetry  to view digital bathymetry data.

You can read more about this program at:

https://noaacoastsurvey.wordpress.com/2018/05/31/noaa-announces-launch-of-crowdsourced-bathymetry-database/

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This photo and thee above are snapshots of data collected using “crowdsourced” bathymetry.

Peaks

+ Participated in a simultaneous medical/fire drill.

MedicalDrill.jpg

“This is a drill, this is a drill. There has been a medical emergency on the starboard stairway of the bridge…” The person in this picture is only acting and not actually injured. The bridge had also simulated a fire which interfered with steering and communications.

MedicalDrill2.jpg

A debrief was held in the Mess after the drills.

FRBTest.jpg

This was a day for drills. The FRB (Fast Rescue Boat) was manually unloaded using a hand brake to simulate loss of power. Earlier in the day, the launch boat was manually loaded back onto the ship. Passengers (including myself) boarded the ship using a rope ladder.

 

 

Brandy Hill: How to Mow the Lawn and Needle Gunnin’, July 3, 2018

NOAA Teacher at Sea

Brandy Hill

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

Temperature:

Sea Water: 29.5° C

Air: 31.1° C

 

Science and Technology Log

Radar

The ship is equipped with AIS or automatic identification system. AIS is the primary method of collision avoidance for water transport. It provides unique identification, position, course, and speed of ships equipped with AIS. All vessels with 300 or more gross tonnage and all passenger ships must be equipped with AIS.

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.

CoastalExplorer

You can see the main scheme and cross lines in this image using the Coastal Explorer program.

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.

HyPack

Hypack software is one point of communication between Survey and the Bridge Watch.

Communication between Survey and the Bridge Watch is critical. Every time the ship makes a turn, the side scan towfish and MVP must be taken in. The Bridge also notifies Survey if there are any hazards or reasons to pull in survey equipment.

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.

Bridge Watch Night Vision

ENS Sydney Catoire explains how important it is to preserve your night vision while maintaining watch, thus the dimming and/or use of red lighting. Her favorite watch time is from 0800-1200.

CO Night Orders from June 28, 2018

CO Night Orders from June 28, 2018

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!

Needle Gun

I was introduced to the needle gun- a high powered tool used for pounding paint and rust off surfaces to prepare them for the wire wheel and paint primer. CO thanked me for my contribution at maintaining the preservation of the TJ.

Revarnishing Deck Work

One of the Thomas Jefferson wooden plaques sanded and receiving a fresh coat of varnish.

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.

Chief Boatswain Bernard Pooser

Chief Boatswain Bernard Pooser

 

Peaks

+ 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.)

 

Brandy Hill: What Lies Beneath the Surface, July 1, 2018

NOAA Teacher at Sea

Brandy Hill

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 1, 2018

 

Weather Data from the Bridge

Latitude: 29° 10.1’ N

Longitude: 093° 54.5’ W

Visibility: 10+ NM

Sky Condition: 3/8

Wind: 16 kts

Temperature:

Sea Water: 29.4° C

Air: 27° C

 

Science and Technology Log

At this point I have been able to understand more of the sonar technology taking place during the survey aboard the Thomas Jefferson. The ship uses two types of sonar: multibeam and side scan. Both work together transmitting and receiving sound pulses to and from the ocean floor. This provides a multispectral analysis.

Julia Wallace, a physical scientist, works at the sonar acquisition station. This requires a large amount of multitasking as she communicates with the bridge (ship steering deck), watches the safety cameras, and makes sure both sonar devices are working correctly.

Julia Wallace, a physical scientist, works at the sonar acquisition station. This requires a large amount of multitasking as she communicates with the bridge (ship steering deck), watches the safety cameras, and makes sure both sonar devices are working correctly.

Multibeam sonar is located underneath the hull of the ship. Multibeam is used to detect bathymetry (the depth of the ocean floor). Multibeam backscatter (reflected wave energy) gives a reading of the surface intensity. For example, a strong signal would mean a harder surface like rock or pipeline. With multibeam sonar, you can also adjust the sound wave frequency. For example, high frequency (primarily used during this survey in the Gulf of Mexico) is used for shallower waters allowing for higher resolution images. Images from multibeam have a color gradient to allow for clear vision of contours and depth differences. One way surveyors aboard the TJ may use backscatter images is to determine areas where bottom sampling might be applicable.

A NOAA ship using mulitbeam sonar. (Courtesy of NOAA)

A NOAA ship using mulitbeam sonar. (Courtesy of NOAA)

Bathymetry acquired using multibeam echosounder layered over a nautical chart.  Blue and green wave lengths penetrate further in water, so the coloring corresponds to this observation. This poster is from a previous Thomas Jefferson hydrographic survey near Savannah, Georgia. (Prepared by CHST Allison Stone)

Bathymetry acquired using multibeam echosounder layered over a nautical chart.  Blue and green wave lengths penetrate further in water, so the coloring corresponds to this observation. This poster is from a previous Thomas Jefferson hydrographic survey near Savannah, Georgia. (Prepared by CHST Allison Stone)

3D bathymetry imagery from the Okeanos Explorer. (NOAA)

3D bathymetry imagery from the Okeanos Explorer. (NOAA)

A close-up view of multibeam data. The third window down shows multibeam backscatter.

A close-up view of multibeam data. The third window down shows multibeam backscatter.

The side scan sonar is used alongside multibeam to provide black and white scans of images. Like multibeam backscatter, side scan measures the intensity of the sound returning from the sea floor. For example, a side scan return with high intensity could indicate a difference in material like pipeline or a wreck. A low intensity value could mean that the side scan sonar waves have reached a muddy substrate. Julia used the analogy of a tennis ball being bounced against a wall of different materials. For example, the tennis ball hitting a concrete wall would bounce back with higher intensity than one being bounced against a soft wall. Side scan sonar is very effective at detecting features that protrude off the sea floor, and for shallow water surveys, typically can see farther and cover a greater area the sea floor than multibeam echosounders alone.

The side scan sonar sensor is located on a torpedo-shaped “towfish” and pulled behind the boat. When viewing side scan images, surveyors typically look for the acoustic shadow cast by a feature protruding off the sea floor. By measuring the length of the acoustic shadow, hydrographers can determine whether the feature requires additional investigation. For example, the outline of a shipwreck, bicycle, or pipeline. However, it can also detect mammals like dolphins or schools of fish.

Diagram of side scan sonar. (Courtesy of thunder bay 2001, Institute for Exploration, NOAA-OER)

Diagram of side scan sonar. (Courtesy of thunder bay 2001, Institute for Exploration, NOAA-OER)

The Thomas Jefferson sidescan sonar on deck.

The Thomas Jefferson sidescan sonar on deck.

In the early morning, the sidescan sonar picked up the image of an incorrectly charted shipwreck. Height is estimated using the "shadow" of the wreck.

In the early morning, the sidescan sonar picked up the image of an incorrectly charted shipwreck. Height is estimated using the “shadow” of the wreck.

Sidescan sonar imagery layered on a nautical chart. It is important to remember that sidescan data does not account for depth, it is a measure of differences in sea floor substrate.

Sidescan sonar imagery layered on a nautical chart. It is important to remember that sidescan data does not account for depth, it is a measure of differences in sea floor substrate.

Look closely and you can see arc lines in the sidescan imagery. Lt. Anthony Klemm explains that these arcs are from ships dragging anchor and stirring up the sea floor.

Look closely and you can see arc lines in the sidescan imagery. Lt. Anthony Klemm explains that these arcs are from ships dragging anchor and stirring up the sea floor.

While this is happening, surveyors are also towing a MVP or Moving Vessel Profiler to capture information about the water column. This is important because multiple factors in the water column need to be corrected in order for accurate sonar calculations. For example, the speed of sound in salt water is roughly 1500 m/s but may change while the ship is traveling over different parts of the sea floor or passing through a thermocline (steep temperature gradient) or halocline (steep salinity gradient). The MVP is similar to the CTD used on the launch boat (see previous post), but the MVP allows the ship to continue moving at about 10 knots (average survey speed), while the CTD must be cast when the ship is stationary.

Information from the Moving Vessel Profiler. From left to right, the MVP tracks sound speed, temperature, and salinity in relation to depth.

Information from the Moving Vessel Profiler. From left to right, the MVP tracks sound speed, temperature, and salinity in relation to depth.

For more information on multispectral analysis and sonar, see these resources:

https://oceanexplorer.noaa.gov/explorations/09bermuda/background/multibeam/multibeam.html

https://oceanservice.noaa.gov/education/seafloor-mapping/how_sidescansonar.html

Personal Log

One of my goals in the classroom is to teach students to be comfortable making and learning from mistakes. Making mistakes in math and science is common and welcome because they lead to great discussion and future change. Often, my sixth graders get discouraged or so caught up in failure that they become paralyzed in making further attempts. While aboard the Thomas Jefferson, I have witnessed several aspects not go according to plan. I think these experiences are important to share because they provide real-life examples of professionals coming together, learning from mistakes, and moving forward.

Around 4:00 am, the towfish side scan sonar became entangled with the MVP. This was a horrendous disaster. The crew spent about 16 hours contemplating the issue and collecting data using the multibeam only, which is less than ideal.  One of XO LCDR McGovern’s many roles aboard the ship is to serve as the investigator. She reviewed tapes of the early morning, talked with the crew, and later held a debrief with all involved. When something like this happens, the ship must write a clear incident report to send to shore. There were many questions about why and how this happened as well how to best proceed. In the end, the towfish and MVP were untangled with no damage present to the sensor. Within the same day, both were cast out and back in use.

I find this to be an astounding example of perseverance and teamwork. Despite being disappointed and upset that a critical tool for collecting accurate data was in dire shape, the crew came up with a plan of action and executed. Part of the engineering and scientific processes include evaluation and redesign. Elements of the sea and a center drift of the side scan lead to a documented new plan and refiguring the process so that this is unlikely to happen again.

Lt. Charles Wisotzsky's sketch of the complications with launching both the sidescan sonar (which tends to centerline) and MVP towfish with a current coming from port side.

Lt. Charles Wisotzsky’s sketch of the complications with launching both the sidescan sonar (which tends to centerline) and MVP towfish with a current coming from port side.

This camera image captures the entanglement of the sidescan sonar and MVP.

This camera image captures the entanglement of the sidescan sonar and MVP.

Peaks

+Saw a tuna eat a flying fish

Flying Fish. (www.ocean.si.edu)

Flying Fish. (www.ocean.si.edu)

+There is a large sense of purpose on the ship. Despite complex sleep schedules to enable 24 hour operations with a smaller crew, people are generally happy and working hard.

+ There seems to be an unlimited supply of ice cream in the ice cream freezer. Junior Officer, ENS Garrison Grant introduced me to a new desert- vanilla ice cream, a scoop of crunchy peanut butter, and chocolate syrup. I also found the rainbow sprinkles.