Lona Hall: Alaska Awaits, May 22, 2019

NOAA Teacher at Sea

Lona Hall

Aboard NOAA Ship Rainier

June 3 – 14, 2019

Mission: Kodiak Island Hydrographic Survey

Geographic Area of Cruise: Kodiak Island, Alaska

Date: May 22, 2019

Personal Introduction

Finishing off the school year has never been so exciting as it is now, with an Alaskan adventure awaiting me!  My students are nearly as giddy as I am, and it is a pleasure to be able to share the experience with them through this blog.

In two weeks, I will leave my home in the Appalachian foothills of Georgia and fly to Anchorage, Alaska.  From there I will take a train to the port city of Seward, where I will board NOAA Ship Rainier.  For 11 days we will travel around Kodiak Island conducting a hydrographic survey, mapping the shape of the seafloor and coastline. The Alaska Hydrographic Survey Project is critical to those who live and work there, since it greatly improves the accuracy of maritime navigational charts, ensuring safer travel by sea.

Lona Hall and students in Mozambique
My Mozambican students, 2013

In the past, I have traveled and worked in many different settings, including South Carolina, Cape Cod, Costa Rica, rural Washington, and even more rural Mozambique.  I have acted in diverse roles as volunteer, resident scientist, amateur archaeologist, environmental educator, mentor, naturalist, and teacher of Language Arts, English Language, Math, and Science.

View of Mount Yonah
Mount Yonah, the view from home in northeast Georgia

I now found myself back in my home state of Georgia, married to my wonderful husband, Nathan, and teaching at a local public school.  Having rediscovered the beauty of this place and its people, I feel fortunate to continue life’s journey with a solid home base.

Lona and Nathan at beach
My husband and I at the beach

Currently I teach Earth Science at East Hall Middle School in Gainesville, Georgia.  For the last five years, I have chosen to work in the wonderfully wacky world of sixth graders.  Our school boasts a diverse population of students, many of whom have little to no experience beyond their hometown.  It is my hope that the Teacher at Sea program will enrich my instruction, giving students a glimpse of what it is like to live and work on a ship dedicated to scientific research.  I am also looking forward to getting to know the people behind that research, learning what motivates them in the work that they do and what aspects of their jobs they find the most challenging.

Did you know?

Kodiak Island is the largest island in Alaska and the second largest in the United States.  It is located near the eastern end of the Aleutian Trench, where the Pacific Plate is gradually being subducted underneath the North American Plate.

David Tourtellot: Draggin’ The Line, July 21st, 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 21st, 2018

Weather Data from the Bridge

Latitude: 29° 11.6357’ N

Longitude: 093° 55.9746’W

Visibility: 10+ Nautical Miles

Sky Condition: 6/8

Wind: Direction: 224°    Speed: 8.5 knots

Temperature:

Seawater: 30.4°C

Air: Dry bulb:31.5°C          Wet bulb: 28.5°C

 

Science and Technology Log

In my previous post, I discussed the ship’s sonar. This time, I’ll go into more detail about the tools the Thomas Jefferson is using to complete its mission. The sonar that the ship uses is multi-beam echosounder sonar, which sends the pings down to the seafloor and receives echoes in a fan shape, allowing the ship to survey a wide swath beneath the ship.

Multibeam Sonar
An illustration of a ship using multi-beam sonar. Image courtesy of NOAA

In addition to the multi-beam sonar, NOAA Ship Thomas Jefferson utilizes two towfish, or devices that are towed in the water behind the ship.

The first is the side scan sonar. Like the multi-beam, this device uses pings of soundwaves to create images of its surroundings. However unlike the multi-beam, the side scan doesn’t capture any data from the area underneath it. Instead, it collects data to its sides.  The side scan is connected to the ship via a cable, and is dragged through the water 6-15 meters above the seafloor. It is great for measuring the intensity of the return of the ping, which provides insights into the makeup of the seafloor.

The side scan towfish
The side scan towfish

The second towfish that the Thomas Jefferson is using is the MVP (like many things on the ship, MVP is an acronym, for Moving Vessel Profiler). The MVP truly gives the ship some of its most valuable data. As I discussed in my previous blog post, in order for us to accurately calculate the distance that the sonar’s pings are traveling, we need to know the amount of time it takes them to travel, as well as the velocity, or the speed, at which they’re moving. The singarounds I mentioned in my last post measure sound velocity, but only at the face of the sonar. Water conditions are not uniform – at the surface, water tends to be warmer, with less salinity. As you get deeper, however, the water tends to be colder and saltier. This means that the velocity of sound changes the deeper you get. Most of the time, the MVP rides just under the surface of the water, but periodically it will get cast down, to approximately 1 meter above the seafloor. It measures the water conditions of the entire water column from the surface to the seafloor, allowing us to calculate sound velocity all the way down.

MVP
The MVP towfish as it is being lowered into the water

The MVP measures the same water qualities as the CTD (a device I discussed in an earlier blog post), however, the MVP has a distinct advantage over the CTD. In order to use a CTD, the ship has to come to a stop while the CTD is lowered into the water. The MVP, however, can be used while the ship is in motion, which greatly increases productivity.

When surveying, many on the crew say it’s like mowing the lawn. The ship will capture a long stretch of data, called a line, and then turn around, and capture another stretch. 4% of these lines are cross lines, which run perpendicular, across a wide swath of lines of captured data. Cross lines allow the survey department to double check that the data they’ve captured is accurate.

Mowing the Lawn
A display of the lines of survey data the ship has captured. Cross lines can be seen running perpendicular to the majority.

 

Personal Log

TJ Bridge Daylight
The bridge of NOAA Ship Thomas Jefferson in the daylight

A couple of days ago, I went up to the bridge shortly after sunset, and I was surprised what I saw. All the lights were off, and the screens of the various instruments had been covered by red filters. I was told that this is for maintaining night vision when on watch. Red light interferes least with our night vision, so anything that gives off light is switched to red.

Bridge at night
The bridge of NOAA Ship Thomas Jefferson at night

While on the bridge, I had the opportunity to ask ENS Garrison Grant (who had recently been selected for a promotion to Lieutenant Junior Grade – congratulations Garrison!) a little about the NOAA Corps. I must admit that I was largely unfamiliar with them before joining the Thomas Jefferson.

The NOAA Corps as we know it today began in 1970, though its roots are much older. As president, Thomas Jefferson (for whom NOAA Ship Thomas Jefferson is named) created the United States Survey of the Coast, which would later evolve into the United States Coast & Geodetic Survey. Their early operations were not unlike the survey work that NOAA Ship Thomas Jefferson is doing today, though their tools were more primitive: surveyors wanting to determine the depths of America’s bodies of water didn’t have the benefit of sonar, and instead used lead lines – lead weights tied to the end of ropes. These surveyors would also play a vital role in our military history. They would often assist artillery, and survey battlefields. This is what led to the United States Coast & Geodetic Survey (and later, the National Oceanic and Atmospheric Administration) to gain a commissioned uniformed service. Due to the rules of war, captured uniformed service members could not be tried as spies.

To join the NOAA Corps today, you need to first have a bachelor’s degree. ENS Grant received his degree from Stockton University in Marine Sciences, but he says that it isn’t a requirement that the degree be in a maritime field. He says that some of his classmates had degrees in fields such as English or Communications. After getting a degree, you then apply to join the NOAA Corps (anyone interested should check out this website: https://www.omao.noaa.gov/learn/noaa-corps/join/applying). If selected, you would then complete the Basic Officer Training Class (BOTC), which generally takes about 6 months. After that, you’d be given your first assignment.

 

Did you know? Before NOAA Ship Thomas Jefferson was operated by the National Oceanic and Atmospheric Administration, it belonged to the U.S. Navy and was known as the U.S.N.S. Littlehales

Taylor Planz: Teachers Must Give Progress Reports, July 20, 2018

NOAA Teacher at Sea

Taylor Planz

Aboard NOAA Ship Fairweather

July 9 – 20, 2018

Mission: Arctic Access Hydrographic Survey

Geographic Area of Cruise: Point Hope, Alaska and vicinity

Date: July 20, 2018 at 10:14am

Weather Data from the Bridge
Latitude: 64° 29.691′ N
Longitude: 165° 26.275′ W
Wind: 4 knots S
Barometer: 767.31 mmHg
Visibility: 10 nautical miles
Temperature: 11.8° C
Sea Surface: n/a
Weather: Overcast, no precipitation

Science and Technology Log

Despite a few setbacks, the crew of NOAA Ship Fairweather worked diligently to complete as much surveying as possible around Point Hope during this leg of the mission. Three small boats were sent out last Saturday, July 14th to each survey part of a “sheet”. A sheet is an area of ocean assigned to a hydrographer to survey and process into a bathymetric map. A bathymetric map is the colorful map produced from survey data that shows ocean depth using colors of the rainbow from red (shallow) to blue (deep). Ultimately, that sheet will be added to a nautical chart. Hydrographer Toshi Wozumi kindly showed me the progress that the ship has made towards the Point Hope survey mission below. The soundings were conducted with “set line spacing” of between 100m and 1,000m between each line in order to cover a satisfactory amount of ground in a feasible timeframe. When a more detailed map is necessary, there will be no empty space between lines and this is known as “full coverage”.

Point Hope survey progress from Leg II
Point Hope survey progress from Leg II

Point Hope is such a unique little piece of land. All of the light blue you see on the map above is actually fresh water from inland. Skinny slices of land separate the salty Arctic water from the fresh water. Hydrographer Christina Belton told me that this area experiences a lot of erosion. In the area we surveyed, you can see an unusually straight line between the deep blue-colored seafloor and the relatively shoal yellow- to green-colored seafloor (shoal is a synonym for shallow, but of the two it is the more common word used by hydrographers). This distinct line is a sand bar where sediment collects from erosion and water currents. I am really interested to see how the bathymetric map develops as the season goes on! Hydrographers are expecting this survey to be very flat and unexciting, but you never know what will show up!

2018 proposed Point Hope survey sheets
2018 proposed Point Hope survey sheets

The tiny little polygon at the bottom left of the picture above is a section of a PARS corridor. PARS is an acronym that stands for Port Access Route Studies, and these studies are initiated by the US Coast Guard when an area may be in need of routing changes or new designated routes for a number of different reasons. According to the US Coast Guard, the Eastern Bering Sea is a relatively shallow sea with depths ranging from 20 – 250 feet. This in combination with outdated nautical charts containing sparse data points can make for dangerous conditions for mariners trying to navigate in and around the Bering Sea. In addition Arctic sea ice is retreating more and more each year, and there is a growing interest in travel through the Northwest Passage, formerly covered in sea ice year round. I have heard that a cruise ship will soon travel the Northwest Passage, and tickets start at $37,000 per person. Any takers?

Section of NOAA's Point Hope to Cape Dyer Nautical Chart
Notice the difference in the soundings to the right of the map (north of Point Hope) and to the left of the map (west of Point Hope). The points to the north were conducted in the 1800s by Russia, and the points to the west were conducted in the mid-1900s by the US. This section shows why more surveying is needed in northern Alaska. Photo source: http://www.charts.noaa.gov/PDFs/16123.pdf

NOAA Ship Fairweather was tasked with surveying a small section of the PARS corridor. We worked on this project during our return trip to Nome. A bathymetric map was not prepared by the time I left the ship, so I was not able to see the data. However, this data will be a very important addition to the US Coast Guard’s maps. You may notice on the map of the proposed survey sheets that the northern border of the polygon follows a longer line. This is the International Date Line and also the border between the US and Russia. NOAA Ship Fairweather had to take special precautions to ensure we did not enter international waters without permission, so we ran a couple of soundings the short way on the edge of the polygon before changing our lines to go the long way. The short lines gave us room to turn the ship around without entering Russian waters. If you have ever mowed your lawn, running lines on the ship is just like mowing lines on your grass. When you get to the end of your yard, you need room to turn the lawn mower around before mowing in the opposite direction. In fact, hydrographers informally refer to the act of collecting data with the MBES as “mowing the lawn”!

NOAA Ship Fairweather will continue to collect data in the Point Hope region for a couple more months. The ship is projected to use 53 days at sea to finish the project. However, this time of year can be difficult for navigating the Bering Sea due to frequent storms. This work requires patience and flexibility, as I witnessed during my time on the ship. In the end, the maps and nautical charts they create will be increasingly valuable as more marine traffic will use the Arctic Ocean during the months when there is no sea ice.

Personal Log

This morning we docked the ship in Nome. It was a bittersweet feeling to step on land once again. I grew to enjoy waking up each morning with water in all directions. The light rocking motion in the evening helped me sleep like a baby! I learned a lot of new information in a short period of time. I also made some new friends among the Fairweather crew and the visitors. Together we endured the 12′ seas of Tuesday’s storm in addition to the Blue Nose initiation! The initiation will forever remain a Navy (and NOAA Corps) secret, but I suppose I can show you the after picture! The ceremony itself was quite a messy ordeal, so we had to rinse off before going back inside the ship. What’s the best way to rinse off at sea? You guessed it! Ice cold Arctic sea water! Not to worry though; safety was the first priority and there were no cases of hypothermia onboard. Upon completing the initiation, the 24 crew members below metamorphosed from slimy wogs to polar bears! The remaining 20 or so crew members had previously earned the name of polar bear.

24 soaking wet but proud Polar Bears!
24 soaking wet but proud Polar Bears!

One thing I learned while aboard NOAA Ship Fairweather is that living and working in the same place with the same people is a unique experience. Your work time and off time are confined to the same spaces. You are always around the same 40 – 50 people. In addition, working in remote areas means fewer modern conveniences like TV and cell phone service. You can’t go out to eat or go shopping until you arrive back in port. It’s not for everyone. What I can say though is that not a single person aboard the ship complained about any of these things! Everyone onboard has learned to adapt to the unique challenges and benefits of their workplace. There are many things to enjoy too! It was so nice not having to cook or do dishes for two weeks! You get to live more simply, which means fewer things to worry about day to day, like getting to work on time and getting to the gym/grocery store/post office/anywhere before it closes or gets too crowded. It’s also a fun place to be! Events like the blue nose initiation boost morale and give everyone fun things to plan and look forward to. I thoroughly enjoyed the mindset shift and gained an appreciation for this kind of work. I will also miss it!

Did You Know?

The most recent soundings for the coastal area north of Point Hope were taken in the 1800s when Russia owned Alaska. They were measured with lead lines, and as you can see in the Point Hope nautical chart, there was a large distance between each measurement.

Answer to Last Question of the Day

What are the eligibility requirements to be in the NOAA Commissioned Officer Corps?

To be eligible for appointment into the NOAA Corps, you must

  • be a US citizen of good moral character
  • be able to complete 20 years of active commissioned service before you turn 62
  • have a baccalaureate degree from an institution accredited by the US Department of Education
  • have at least 48 semester hours in science, math, or engineering related to NOAA’s missions
  • pass a mental and physical examination
  • be able to maintain a “secret” security clearance
  • be able to pass a test for illegal drug use.

Sources:
US Coast Guard (2017). Appendix B – Hydrographic Quality Analysis. Bering Sea PARS. https://www.navcen.uscg.gov/pdf/PARS/Bering_Strait_PARS_Appendix_B.pdf.

Taylor Planz: Surveying 101, July 18, 2018

 

NOAA Teacher at Sea
Taylor Planz
Aboard NOAA Ship Fairweather
July 9 – 20, 2018

 Mission: Arctic Access Hydrographic Survey
Geographic Area of Cruise: Point Hope, Alaska and vicinity
Date: July 18, 2018 at 10:15am

Weather Data from the Bridge
Latitude: 66° 24.440′ N
Longitude: 163° 22.281′ W
Wind: 17 knots SW, gusts up to 38 knots
Barometer: 758.31 mmHg
Visibility: 5 nautical miles
Temperature: 12.2° C
Sea Surface 9.6° C
Weather: Overcast, no precipitation

Science and Technology Log

NOAA Ship Fairweather has a variety of assignments in different parts of the west coast each year, mostly in Alaska. They also work with many different organizations. In April of 2018, the US Geological Survey, or USGS, hired the ship to complete the last part of the survey of a fault line, the Queen Charlotte Fault, which lies west of Prince of Wales Island, Alaska. This was a joint venture between the US and Canada because it is the source of frequent and sometimes hazardous earthquakes. The Queen Charlotte Fault lies between the North American Plate and the Pacific Plate. The North American Plate is made of continental crust, and the Pacific Plate is made of oceanic crust. The two plates slide past one another, so the plate boundary is known as a transform, or strike slip, fault.

Queen Charlotte fault area
This image is from the USGS, who have been surveying the Queen Charlotte Fault area for many years. Photo Source: https://soundwaves.usgs.gov/2016/01/

The image to the right came from the USGS. Notice the two black arrows showing the directions of the North American and Pacific plates. Strike slip faults, such as this one, have the potential to produce damaging earthquakes. The San Andreas Fault in California is another example of a strike slip fault. The Queen Charlotte Fault moves relatively fast, with an average rate of 50 mm/year as shown in the photo. The USGS explains the Queen Charlotte fault beautifully in this article.

The image below was created after hydrographers on NOAA Ship Fairweather processed the data from their survey in April. The colors show relative depth across the fault, with red being the shoalest areas and blue being the deepest areas. In the top right section, you can see Noyes Canyon. There are many finger-shaped projections, which are result from sediment runoff. Notice that the color scheme in this area does not have much orange or yellow; it basically goes from red to green. If you were to look at this map in 3-D, you would see in those areas that the sea floor dramatically drops hundreds of meters in a very short distance.

Queen Charlotte Fault and Noyes Canyon
Queen Charlotte Fault and Noyes Canyon. Photo Courtesty of HST Ali Johnson

It is also worth noting what can be found in the remainder of this image. When NOAA finishes their survey, two different products are formed. The first is the colored map, which you see to the far left of the image. This is useful for anyone interested in the scientific components of the area. Mariners need the information as well, but a colored schematic is less useful for marine navigation, so nautical charts are produced (or updated) for their use. A nautical chart looks just like the remainder of this image. Small numbers scattered all over the white part of the map (ie – the water) show the depth in that area. The depth can be given in fathoms, meters, or feet, so it is important to find the map’s key. The purpose of the charts is to communicate to mariners the most navigable areas and the places or obstacles that should be avoided. The nautical charts usually have contour lines as well, which give a better picture of the slope of the sea floor and group areas of similar depth together.

Lower half of Queen Charlotte Fault, photo courtesy of HST Ali Johnson
Lower half of Queen Charlotte Fault, photo courtesy of HST Ali Johnson

The photo above is a closer view of the Queen Charlotte Fault. Can you see the fault? If you cannot see it, look at the line that begins in the bottom center of the photo and reaches up and to the left. Do you see it now? On the left side of the fault lies the Pacific Plate, and on the right side lies the North American Plate. If you look even closer, you might find evidence of the plates sliding past each other. The areas that resemble rivers are actually places where sediment runoff imprinted the sea floor. If you observe closely, you can see that some of these runoff areas are shifted at the location of the fault. Scientists can measure the distance between each segment to determine that average rate of movement at this fault line.

I also wanted to briefly mention another small side project we took on during this leg. A tide buoy was installed near Cape Lisburne, which is north of Point Hope. The buoys are equipped with technology to read and communicate the tidal wave heights. This helps hydrographers accurately determine the distance from the sea surface to the sea floor. The buoy will remain at its station until the end of the survey season, at which time it will be returned to the ship.

 

 

Personal Log

Northwest Alaska may not be a breathtaking as Southeast Alaska, but it has sure been an interesting trip! It amazes me that small communities of people inhabit towns such as Nome, Point Hope, and Barrow (which is about as far north as one can travel in Alaska) and endure bone-chilling winter temperatures, overpriced groceries, and little to no ground transportation to other cities. Groceries and restaurant meals are expensive because of the efforts that take place to transport the food. During my first day in Nome, I went to a restaurant called the Polar Cafe and paid $16 for an omelette! Although the omelette was delicious, I will not be eating another during my last day in Nome on Friday. It is simply too expensive to justify paying that much money. I also ventured to the local grocery store in hopes of buying some Ginger Ale for the trip. Consuming ginger in almost any form can help soothe stomach aches and relieve seasickness. Unfortunately ginger ale was only available in a 12-pack that happened to be on sale for $11.99. I decided to leave it on the shelf. Luckily the ship store has ginger ale available for purchase! The ship store is also a great place to go when your sweet tooth is calling!

The Ship Store
The Ship Store opens most nights for personnel to buy soda, candy, or even t-shirts!

 

Did You Know?
The Queen Charlotte fault was the source of Canada’s largest recorded earthquake! The earthquake occurred in 1949 and had a magnitude of 8.1!

Question of the Day
As mentioned above, northern Alaska reaches temperatures colder than most people can even imagine! Nome’s record low temperature occurred on January 27, 1989. Without using the internet, how cold do you think Nome got on that day?

Answer to Last Question of the Day:
How does a personal flotation device (PFD) keep a person from sinking?

When something is less dense than water it floats, and when it is more dense than water it sinks. Something with the same density as water will sit at the surface so that it lies about equal to the water line (picture yourself laying flat on the surface of a lake). Your body is over 50% water, so the density of your body is very close to the density of water and you naturally “half float”. A PFD, on the other hand, is made up of materials which have a lower density than water and they always float completely above water. When you wear a PFD, your body’s total density is a combination of your density and the PFD’s density. Therefore, the total density becomes less than the density of water, and you float!

Sources:
Danny, et al. (2016). Investigating the Offshore Queen Charlotte-Fairweather Fault System in Southeastern Alaska and its Potential to Produce Earthquakes, Tsunamis, and Submarine Landslides. USGS Soundwaves Monthly Newsletter. https://soundwaves.usgs.gov/2016/01/.

Torresan, L (2018). Earthquake Hazards in Southeast Alaska. USGS Pacific Coastal and Marine Science Center. https://walrus.wr.usgs.gov/geohazards/sealaska.html.

 

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!