Hayden Roberts: Playing Hide and Seek with Sonar, July 16, 2019

NOAA Teacher at Sea

Hayden Roberts

Aboard NOAA Ship Oregon II

July 8-19, 2019


Mission: Leg III of SEAMAP Summer Groundfish Survey
Geographic Area of Cruise: Gulf of Mexico
Date: July 16, 2019

Weather Data from the Bridge
Latitude: 28.51° N
Longitude: 84.40° W
Wave Height: 1 foot
Wind Speed: 6 knots
Wind Direction: 115
Visibility: 10 nm
Air Temperature: 30.8°C
Barometric Pressure: 1021 mb
Sky: Clear


Science Log

In my previous blog, I mentioned the challenges of doing survey work on the eastern side of the Gulf near Florida. I also mentioned the use of a probe to scan the sea floor in advance of trawling for fish samples. That probe is called the EdgeTech 4125 Side Scan Sonar. Since it plays a major role in the scientific research we have completed, I wanted to focus on it a bit more in this blog. Using a scanner such as this for a groundfish survey in the Gulf by NOAA is not typical. This system was added as a precaution in advance of trawling due to the uneven nature of the Gulf floor off the Florida Coast, which is not as much of a problem the further west one goes in the Gulf. Scanners such as these have been useful on other NOAA and marine conservation research cruises especially working to map and assess reefs in the Gulf.

deploying side scan
Preparing to put the side scan over board.

Having seen the side scanner used at a dozen different research stations on this cruise, I wanted to learn more about capabilities of this scientific instrument. From the manufacturer’s information, I have learned that it was designed for search and recovery and shallow water surveys. The side scanner provides higher resolution imagery. While the imagining sent to our computer monitors have been mostly sand and rock, one researcher in our crew said he has seen tanks, washing machines, and other junk clearly on the monitors during other research cruises.

This means that the side scanner provides fast survey results, but the accuracy of the results becomes the challenge. While EdgeTech praises the accuracy of its own technology, we have learned that accurate readings of data on the monitor can be more taxing. Certainly, the side scanner is great for defining large items or structures on the sea floor, but in areas where the contour of the floor is more subtle, picking out distinctions on the monitor can be harder to discern. On some scans, we have found the surface of the sea floor to be generally sandy and suitable for trawling, but then on another scan with similar data results, chunks of coral and rock have impeded our trawls and damaged the net.

Side scan readout
Sample scan from monitor in the computer lab. The light areas are sandy bottom. The dark is either seaweed or other plant material or rocks. The challenge is telling the difference.


Did You Know?

In 1906, American naval architect Lewis Nixon invented the first sonar-like listening device to detect icebergs. During World War I, a need to detect submarines increased interest in sonar. French physicist Paul Langévin constructed the first sonar set to detect submarines in 1915. Today, sonar has evolved into more sophisticated forms of digital imaging multibeam technology and side scan sonar (see https://oceanexplorer.noaa.gov/explorations/lewis_clark01/background/seafloormapping/seafloormapping.html for more information).


Personal Log

When I first arrived aboard Oregon II, the new environment was striking. I have never spent a significant amount of time on a trawling vessel or a research ship. Looking around, I took many pictures of the various features with an eye on the architectural elements of the ship. One of the most common fixtures throughout the vessel are posted signs. Lamented signs and stickers can be found all over the ship. At first, I was amused at the volume and redundancy, but then I realized that this ship is a communal space. Throughout the year, various individuals work and dwell on this vessel. The signs serve to direct and try to create consistency in the overall operation of the ship and the experience people have aboard it. Some call the ship “home” for extended periods of time such as most of the operational crew. Others, mostly those who are part of the science party, use the vessel for weeks at a time intermittently. Before I was allowed join the science party, I was required to complete an orientation. That orientation aligns with policies of NOAA and the expectation aboard Oregon II of its crew. From the training, I primarily learned that the most important policy is safety, which interestingly is emblazoned on the front of the ship just below the bridge.

Safety First!
Safety First!

The signs seem to be reflective of past experiences on the ship. Signs are not only reminders of important policies and protocols, but also remembrances of challenges confronted during past cruises. Like the additional equipment that has been added to Oregon II since its commission in 1967, the added signs illustrate the history the vessel has endured through hundreds of excursions.

Oregon II 1967
Bureau of Commercial Fisheries Ship Oregon II (1967), which was later transferred to NOAA when the administration was formed in 1970.
Oregon II 2017
NOAA Ship Oregon II in 2017 on its 50th Anniversary.

Examples of that history is latent in the location and wording of signs. Posted across from me in the computer lab are three instructional signs: “Do not mark or alter hard hats,” “Keep clear of sightglass do not secure gear to sightglass” (a sightglass is an oil gauge), and “(Notice) scientist are to clear freezers out after every survey.”

signs collage
A collage of four signs around NOAA Ship Oregon II
more signs
Another collage of four signs around NOAA Ship Oregon II
even more signs
Another collage of signs around NOAA Ship Oregon II

Author and journalist Daniel Pink talks about the importance of signs in our daily lives. His most recent work has focused on the emotional intelligence associated with signs. Emotional intelligence refers to the way we handle interpersonal relationships judiciously and empathetically. He is all about the way signs are crafted and displayed, but signs should also be thought of in relation to how informative and symbolic they can be within the environment we exist. While the information is usually direct, the symbolism comes from the way we interpret the overall context of the signs in relation to or role they play in that environment.

Jeff Peterson: The Work in the Eastern Gulf, July 19, 2018

NOAA Teacher at Sea

Jeff Peterson

Aboard NOAA Ship Oregon II

July 9 – 20, 2018

 

Mission: Summer Groundfish Survey

Geographic Area of Cruise: Gulf of Mexico

Date: July 19, 2018

 

Weather Data from the Bridge

Date: 2018/07/19

Time: 16:34:47

Latitude: 29 57.6 N

Longitude: 087 02.60 W

Speed over ground: 7.3 knots

Barometric pressure: 1014.49

Relative humidity: 84%

Air temperature: 26.8 C

Sea wave height: 1 m

 

Science and Technology Log

We arrived off the coast of Florida on the evening of Sunday, July 15, and sampled stations in the eastern Gulf until the afternoon of Thursday, July 19. We used the same fishing method during this part of the cruise (bottom trawling), but added a step in the process, deploying side scan sonar in advance of every trawl. This measure was taken both to protect sea life on the ocean floor (sponges and corals) and to avoid damaging equipment. The sea bottom in this part of the Gulf—east of the DeSoto Canyon—is harder (less muddy) and, in addition to coral and sponge, supports a number of species markedly different than those seen in the western Gulf.

 

Side Scan Sonar

In contrast to single-beam sonar, which bounces a single focused beam of sound off the bottom to measure depth, side scan sonar casts a broader, fan-like signal, creating nuanced readings of the contour of the ocean floor and yielding photo-like images.

Towed Side Scan

How side scan sonar works: The harder the object, the stronger the image returned. See: https://oceanservice.noaa.gov/education/seafloor-mapping/how_sidescansonar.html#

 

Side scan sonar device

Side scan sonar device in its cradle.

 

 

Rigged and ready for deployment.

Rigged and ready for deployment. Signals from the sonar are conducted up the cable and picked up by the electrically powered lead on the block.

 

on its way in

Side scan sonar on its way in astern.

 

descending

Side scan sonar just beneath the surface & descending.

 

When we arrive a station in this part of the Gulf, we begin by traversing, covering the usual distance (1.5 miles), but then turn around, deploy the side scan sonar, and retrace our course. Once we’ve returned to our starting point, we recover the sonar, turn around again, and—provided the path on the sea bottom looks clear—resume our course through the station, this time lowering the trawl. If the side scan reveals obstructions, it’s a no-go and the station is “ditched.”

 

Coming about

Coming about before deploying the side scan sonar.

 

 

And Now for Something Completely Different . . . Fish of the Eastern Gulf

Panama City, Florida

Off Panama City, Florida – Tuesday morning, July 17, 2018

We spent the first half of this leg of the survey in the western Gulf of Mexico, going as far west as the Texas-Louisiana border. The second half we’re spending in the eastern Gulf, going as far east as Panama City. From here we’ll work our way westward, back to our homeport in Pascagoula.

Thanks to different submarine terrain in the northeastern Gulf—not to mention the upwelling of nutrients from the DeSoto Canyon—it’s a different marine biological world off the coast of Florida.

Here’s a closer look at the submarine canyon that, roughly speaking, forms a dividing line between characteristic species of the western Gulf and those of the eastern Gulf:

Bathymetric map of the Gulf of Mexico

Bathymetric map of the Gulf of Mexico, with proposed dive sites for Operation Deep-Scope 2005 indicated by red arrows and yellow numbers. Site #1 is on the southwest Florida Shelf in the Gulf of Mexico, where deep-water Lophilia coral lithoherms are found. #2 is DeSoto Canyon, a deep erosional valley where upwelling of deep nutrient rich water means greater animal abundances. #3 is Viosca Knoll, the shallowest site, where spectacular stands of Lophelia provide abundant habitat for other species. See: https://oceanexplorer.noaa.gov/explorations/05deepscope/background/geology/media/map.html

 

And here’s a selection of the weird and wonderful creatures we sampled in the eastern Gulf. As this basket suggests, they’re a more brightly colored, vibrant bunch:

Basket of catch

A basket of fish. Upper right: Lane Snapper, Lutjanus synagris. On the left: Sand Perch, Diplectrum formosum. The plentiful scallops? Argopecten gibbus.

 

 

Sand Perch, Diplectrum formosum

Sand Perch, Diplectrum formosum

Razorfish, Xyrichtys novacula

Razorfish, Xyrichtys novacula

A basket of Xyrichtys novacula

A basket of Xyrichtys novacula

 

Angelfish, Holacanthus bermudensis

Angelfish, Holacanthus bermudensis

Angelfish closeup

Holacanthus bermudensis details: tail fins (front specimen), pectoral fin & gill (behind)

 

Jackknife Fish, Equetus lanceolatus

Jackknife Fish, Equetus lanceolatus

Lined Seahorse, Hippocampus erectus

Lined Seahorse, Hippocampus erectus

 

 

Argopecten gibbus

Argopecten gibbus (all 2,827 of them)

Pink Shrimp, Farfantepenaeus duorarum.

Pink Shrimp, Farfantepenaeus duorarum. Note the signature “pink” spot by my thumb.

 

Calamus

Calamus

 

Lionfish, Pterois volitans

Invasive scourge of the Gulf: Lionfish, Pterois volitans

Lionfish, Pterois volitans

Lionfish, Pterois volitans

 

Burrfish, Chilomycterus schoepfii

Burrfish, Chilomycterus schoepfii

 

 

Scorpionfish (aka Barbfish), Scorpaena brasiliensis

Scorpionfish (aka Barbfish), Scorpaena brasiliensis

 

Southern Stargazer, Astroscopus y-graecum (juvenile)

Southern Stargazer, Astroscopus y-graecum (juvenile)

 

Ocellated Moray Eels, Gymnothorax saxicola

Ocellated Moray Eels, Gymnothorax saxicola

 

Trumpetfish, Aulostomus maculatus

Trumpetfish, Aulostomus maculatus

 

 

Video credit: Will Tilley

 

debris

Mysterious debris: A bottom-dwelling payphone?

 

Personal Log

Our move into the eastern Gulf marks the midpoint of the cruise, and we’ll be back to Pascagoula in a few short days. The seas haven’t been as serenely flat as they were in the eastern Gulf, nor has the sky (or sea) been its stereotypically Floridian blue, but I’ve found life aboard ship just as pleasurable and stimulating.

storm

A squall on Monday morning, July 16, 2018. Off the stern there to starboard, Blackfin Tuna were jumping.

 

In my final blog post, I’ll have more to say about all the great folks I’ve met aboard NOAA Ship Oregon II—from its Deck Department members and Engineers, to its Stewards and NOAA Corps officers and inimitable Captain—but here want to reiterate just how thoughtful and generous everybody’s been. The “O2” is a class act—a community of professionals who know what they’re about and love what they do—and I couldn’t be more grateful to have visited their world for a while and shared their good company.

Busy as we’ve been, I haven’t had much time for sketching during this part of the cruise, and, as the selection of photos above suggests, I’ve concentrated more on taking pictures than making them. Still, I’ve begun a small sketch of the ship that I hope to complete before we reach Pascagoula. It’s based on a photograph that hangs in the galley, and that I’m going to attempt to reproduce actual size (3 3/8” x 7”) . Here’s where things stand early on in the process:

IMG_8230 2.jpg

Work in progress: sketch of NOAA Ship Oregon II

 

Did You Know?

Any of the western Gulf fish in the basket from my last blog post? Here it is again:

Basket of Fish from Western Gulf

Basket of Fish from Western Gulf

And here is a visual key to the four species I was fishing for, each figuring prominently in my blog post for July 15:

Basket of fish revision

Basket of Fish from Western Gulf: now color-coded

1: Red Snapper, Lutjanus campechanus

2: Longspined Porgy, Stenotomus caprinus

3: Gulf Butterfish, Peprilus burti

4: Brown Shrimp, Farfantepenaeus aztecus

A few Stenotomus caprinus and Peprilus burti have been left unhighlighted. Can you find them?

Kimberly Scantlebury: The Night Shift, May 10, 2017

NOAA Teacher at Sea

Kimberly Scantlebury

Aboard NOAA Ship Pisces

May 1-May 12, 2017

Mission: SEAMAP Reef Fish Survey

Geographic Area of Cruise: Gulf of Mexico

Date: May 10, 2017

Weather Data from the Bridge

Time: 15:36

Latitude: 2804.2177  N, Longitude: 9042.0070 W

Wind Speed: 10.2 knots, Barometric Pressure: 1016.8 hPa

Air Temperature: 26.1 C, Water Temperature: 24.89 C

Salinity: 36.49 PSU, Conditions: Some cloud, light wind, 2-4 foot waves

Science and Technology Log

Research vessels do not just work during the day. It is a 24/7 operation. Tonight I checked in with the night shift to learn more about the sonar mapping that has been done in the dark ever since I boarded NOAA Ship Pisces.

IMG_3081

Algebra I level math in action!

The first thing I noticed entering the dry lab was a pad of paper with math all over it. Todd, the survey technician I interviewed earlier, had noticed the the picture the ship’s sonar was producing had a curved mustache-like error in the image. Details like temperature need to be taken into account because water has different properties in different conditions that affect how sound waves and light waves move through it. He used the SOH-CAH-TOA law to find the speed of sound where the face of the transducer head was orientated. He found a six meter difference between the laser angle and what the computer was calculating. Simple trigonometry on a pad of paper was able to check what an advanced computer system was not.

NOAA Ship Pisces is also equipped with an advanced multibeam sonar. (Sonar stands for SOund NAvigation and Ranging.) In fact, there are only eight like it in the world. One of Todd’s goals before he retires from NOAA is to tweak it and write about it so other people know more about operating it. Since they are so few and you need to go to them, there are fewer publications about it.

Another mapping device is the side scan sonar. It is towed behind the vessel and creates a 300 meter picture with a 50 meter blind spot in the center, which is what is underneath the device. Hydrographic vessels have more sonars to compensate for this blind spot. The purpose of the mapping is to identify new habitat areas, therefore expanding the sampling universe of the SEAMAP Reef Fish Surveys.

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Up on the bridge looks much different. The lights are off and monitors are covered with red film to not ruin the crew’s night vision. Everything is black or red, with a little green coming from the radar displays. This is to see boats trying to cross too close in front of NOAA Ship Pisces or boats with their lights off. Lieutenant Noblitt and Ensign Brendel are manning the ship.

Ensign Brendel noted to me that, “We have all of this fancy equipment, but the most important equipment are these here binoculars.” They are always keeping a lookout. The technology on board is built for redundancy. There are two of most everything and the ship’s location is also marked on paper charts in case the modern equipment has problems.

There are international rules on the water, just like the rules of the road. The difference is there are no signs out here and it is even less likely you know who is following them. Each boat or ship has a series of lights that color codes who they are or what they are doing. Since NOAA Ship Pisces is restricted in maneuverability at night due to mapping, they have the right of way in most cases. It is also true that it takes longer for larger vessels to get out of the way of a smaller vessel, especially in those instances that the smaller one tries to pass a little too close. This did happen the night before. It reminds me of lifeguarding. It is mostly watching, punctuated with moments of serious activity where training on how to remain calm, collected, and smart is key.

Personal Log

It has been a privilege seeing and touching many species I have not witnessed before. Adding to the list of caught species is bonito (Sarda sarda) and red porgy (Pagrus pagrus). I always think it is funny when the genus and species is the same name. We have also seen Atlantic spotted dolphins (Stenella frontalis) jumping around. There are 21 species of marine mammals indigenous to the Gulf of Mexico, most in deep water off of the continental shelf. I also learned that there are no seals down here.

One of the neatest experiences this trip was interacting with a sharksucker (Echeneis naucrates). It has a pad that looks like a shoe’s sole that grips to create a suction that sticks them to their species of choice. The one we caught prefers hosts like sharks, turtles…and sometimes science teachers.

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Did You Know?

Fishing boats use colored lights to indicate what kind of fishing they are doing, as the old proverb goes red over white fishing at night, green over white trawling tonight. Vessels also use international maritime signal flags for communication during the day.

Yaara Crane: First Day Aboard, June 22, 2013

NOAA Teacher at Sea
Yaara Crane
Aboard NOAA Ship Thomas Jefferson
June 22, 2013 – July 3, 2013

Mission: Hydrographic Survey
Geographical area of cruise: Mid-Atlantic
Date: Saturday, June 22, 2013

Latitude: 38.81°N
Longitude: 75.10°W

Weather Data from Bridge:
Wind Speed: 10.27 knots
Surface Water Temperature: 20.59°C
Air Temperature: 20.60°C
Relative Humidity: 79.00%
Barometric Pressure: 1023.18mb

Science and Technology Log

The TJ

My first view of the NOAA ship Thomas Jefferson.

This morning I came aboard the Thomas Jefferson via small boat transfer from the pilot station dock in Lewes, Delaware. Since coming on board, I have been welcomed by so many people, toured the ship, had a safety training, cautiously drove the small boat around the Delaware Bay, and tried to learn some background about hydrographic surveys. That is quite a lot of new things to process in only 5 hours!

The major purpose of hydrography is to create a thorough imaging of the ocean floor, particularly to warn mariners of any obstructions or shallows. There is evidence that nautical charts showing depth have been in use since as early as the sixth century BCE, and can easily be created through the use of a lead weight and a string. These days, NOAA ships have much more high tech ways of surveying the ocean floor. The Thomas Jefferson spends most of its time at sea charting waterways and coastlines to ensure safe travels for both private and commercial mariners to be able to navigate safely. Priorities in a nautical charting mission are based on factors including: waterway usage rates, stakeholder requests, rates of change to the sea floor (both natural and anthropogenic), and age of the chart’s source. For example, a waterway to a port used by oil tankers would be very important to survey because the result of a tanker running headlong into an obstruction would be disastrous. After Hurricane Sandy hit the East Coast in October 2012, the Thomas Jefferson was assigned to survey the sea floor of New York City’s harbor in case of any new obstructions that might have been blown in undetected. No other ship was allowed to sail through the harbor until the Coast Guard received the new charts. So far this summer, the Thomas Jefferson has already spent countless hours surveying the area around Long Island Sound and the Delaware Bay.

To have a better grasp of the major scientific research that occurs on a hydrographic research vessel, I spent a portion of the afternoon speaking with Ensign Andrew Clos. Ensign Clos mentioned that the two most important tools for data collection are the side scan sonar (SSS) and the multi-beam echo sounder (MBES). These two tools work through the use of sound waves to collect both 2D and 3D data. The SSS and the MBES send sound waves which are reflected back to the ship and transformed into images analyzed by the scientists on board. The side scan sonar is towed by the ship in very carefully spaced horizontal lines to gather the initial data about the existence of any objects in the water. An acoustic image is created and analyzed for anything out of the ordinary, in which case the MBES is launched for further investigation. The MBES is hull-mounted to the ship and survey launches, and lets out sound waves in a 128° cone which much more accurately determines the depth and position of the object. The MBES can collect millions of data points in a day, which is converted into three-dimensional images.

side scan sonar from NOAA

This SSS image is of the wreck of the Herbert D. Maxwell. The white area to the upper right is called a shadow because the sonar cannot pass into that area. (Photo courtesy of NOAA)

mbes noaa

This MBES image shows a fuller picture of the wreck of the Herbert D. Maxwell. (Photo courtesy of NOAA)

The scientists aboard spend many hours sifting through the data, and correcting the data for differences in depth based on tidal flows and water data. Sound waves travel through water at approximately 1500 meters/second (m/s), much faster than the 340 m/s in air. However, differences in salinity and temperature can impact the accuracy of measurements. All of the branches of NOAA must work together to piece together the puzzle of the ocean floor.

Personal Log

Rehoboth Beach

Hanging out at the beach the day before getting aboard the TJ.

This has been quite a busy week for me, which has culminated in this spectacular adventure. Monday was our last day of final exams, and today I feel like that was a lifetime ago! I spent most of yesterday morning driving to Delaware, and was rewarded with spending the afternoon relaxing on Rehoboth Beach. As it turns out, relaxing is on the table for tomorrow, too. The TJ is waiting on a repair to the MBES, and will need to stay anchored close to port for at least one more day. Commander Krepp has allowed some of the members of the crew to arrange for a day out paddling and kayaking around the beach. Still, there is work to be done and safety to consider aboard a NOAA vessel, so even that excursion has to be carefully managed into two shifts.

Weather-wise, it has been a beautiful weekend. There is a slight breeze, but not enough to make waves worth mentioning. The TJ is also anchored just behind a breakwater which helps to keep waves at bay. All of this adds up to a very calm shipboard experience, with barely any feeling of rocking or swaying while aboard the ship. I have rarely suffered from motion sickness and hope to continue my good record throughout this cruise. No seasickness means I can make my way over to the ice cream bar for a little afternoon snack…

Did You Know?

Fossil remains of horseshoe crabs have been found spanning approximately the last 450 million years. They are called living fossils because they are some of the rare species that have survived extinction with little genetic diversity.

Horseshoe crab

The horseshoe crab is a living fossil found on Delaware’s shores.

 

Chuck Gregory, August 13, 2007

NOAA Teacher at Sea
Chuck Gregory
Onboard NOAA Ship Thomas Jefferson
August 12 – 24, 2007

Mission: Hydrographic Survey
Geographical Area: New York Harbor
Date: August 13, 2007

Chuck's stateroom aboard the NOAA Ship THOMAS JEFFERSON.  During his voyage, Chuck (bottom bunk) shared his stateroom with Ensign Andrew Ostapenko (top bunk).

Chuck’s stateroom aboard the ship. During his voyage, Chuck (bottom bunk) shared his stateroom with Ensign Andrew Ostapenko (top bunk).

“He who knows best knows how little he knows.” ~Thomas Jefferson

Andy’s alarm clock went off around 0600h. I was already awake but comfortable, so I didn’t get up right away. I could hear that one of the Megan’s was using the shower. The staterooms on our deck have an interesting arrangement – two guys sharing a bath (shower and toilet) with two gals (Megan & Megan). The trick is to knock first and, once the coast is clear, to enter and lock the gal’s door from the inside.  But the real trick is to remember to UNlock the gal’s door before leaving. Stay tuned…

After Andy used the shower it was my turn.  I’ve used smaller showers, but not much smaller.  The water pressure was good, and the temperature comfortable.  I am now awake!  I quickly dressed and went to the Mess Hall to catch up on some eating.  I met the CO, and a few other crew. I also met Tom who is from the NOAA office in Silver Springs, Maryland (near DC). He is on board to observe and get a better idea what the ships do to gather the data.  Breakfast was simple (I am trying to lose about 10 lbs.) – cereal, fruit and coffee – and I was off to take a few pictures before we headed out to sea.

The morning sky is clear and the day will be hot, so it’s probably a good thing we are going to be on the water. Next to us on the pier a group of visitors was getting the tour of the USS INTREPID. Manhattan and the surrounding area was enshroud in a gray haze.  It’s going to be a learning day and I have a lot to learn.  For now, I think it’s time for me to stop writing and take my Dramamine.

The Plan of the Day (Day #225) for the THOMAS JEFFERSON is as follows:
Sunrise = 0604h Sunset = 1958h 0000h
Ship moored alongside Stapleton Pier, Staten Island, NY 1100h
Ship underway 1130h
Deploy 31’ Launches (3101 & 3102) 1215h
Anchor @ Sandy Hook Anchorage 1545h
Retrieve launches

Tides for Sandy Hook Low @ 0258h (-0.2 ft.) & 1459h (0.2 ft.); High @ 0855h (5.0 ft.) & 2105h (5.6 ft.)  Currents in Sandy Hook Channel Flood: 0604h (2.0 kts.) & 1814h (2.3 kts.); Ebb: 1212h (1.6 kts.) & 0041h (1.7 kts.)  Weather from Sandy Hook to Fire Island AM: W winds 10-15 kts., seas 2-3 ft.; PM: NW winds 10 kts., seas 2 ft.

Today was a learning day as I wanted to learn more about the bathymetry instruments. The THOMAS JEFFERSON is equipped with a Klein 5000 Side Scan Sonar (aka SSS Fish).  Informative place settings dot the mess hall and I was able to learn the basics of the equipment from them:

“The side-scan sonar is NOT just like a photo of the ocean floor.  Objects get “stretched and distorted”. They need to be interpreted.”

“The SSS Fish data can be affected by: 1) tides, 2) survey speed, 3) sea conditions, 4) angle of incidence of sound waves, 5) launch (or ship) attitude (roll, yaw & heave), 6) etc.”

“When sound waves from the SSS Fish are reflected off an object a dark or “hard” return is created in the data. The object blocks the sound waves from traveling beyond it, which creates a “light colored shadow”.

“Unlike Multibeam Sonar, side-scan sonar created better images of the bottom when objects are off to the side, rather than directly beneath the instrument.”

“Side-scan sonar sends out an acoustic pulse out both sides of the vessel.  The intensity of the acoustic reflection from each side is measured for a period of time.  An image of a stripe of sea bottom is made with each pulse.”

At 1730h I met with Peter the hydrosurvey data technician and observed him downloading today’s data. Peter applied a series of corrections (heave, tide and sound velocity) to the data. This time consuming process took about two hours.  This data will be sent to NOAA’s Atlantic Hydrographic Branch (AHB) where it will be reviewed, checked, cross checked, and additional data will be added if needed (e.g., from Army Corp).  The raw data is also sent to the National Geographic Data Center in Boulder, CO where it is archived. From AHB the data is sent to NOAA’s Chart Division where it is made into the navigation charts we commonly use.  FOO and Acting XO Chris informed me I will be going on one of the launches tomorrow.  #3102 with SSS Fish and Multibeam (MBES).  I can’t wait.  I’m going to need a good night’s sleep as we’ll be on the launch for about 10 hours!  Good night!!

Candice Autry, August 16, 2006

NOAA Teacher at Sea
Candice Autry
Onboard NOAA Ship Thomas Jefferson
August 7 – 18, 2006

Mission: Hydrographic Survey
Geographical Area: Northwest Atlantic
Date: August 16, 2006

“Experiences on the Fast Rescue Boat” 

TAS Candice Autry prepares to use the CTD instrument which collects water information related to conductivity, temperature, and depth.

Candice Autry prepares to use the CTD instrument which collects water information related to conductivity, temperature, and depth.

Science and Technology Log 

Today I had the opportunity to go out on the Fast Rescue Boat (FRB) to use the conductivity, temperature, depth (CTD) instrument in various places in the harbor.  The CTD looks like a simple white tube; however, the capabilities of the CTD are far from simple!  This devise provides essential data for scientists. Three of us boarded the small FRB, loaded the CTD, and were off to our locations. The first observation noted is that being on the fast rescue boat is a different boating experience compared to the launches and the THOMAS JEFFERSON. The “fast” part of the description is fitting; the boat moves quickly!  The main function of the CTD is to collect data about how the conductivity and temperature of water changes relative to depth. Conductivity and temperature information is important because the concentration of the salt of the seawater can be determined by these two changing variables.

Candice Autry holds the CTD instrument. We collected information from three locations; once in the morning and then again in the afternoon.

Candice Autry holds the CTD instrument. We collected information from three locations; once in the morning and then again in the afternoon.

The CTD devise can also help surveyors determine the speed of sound in the water. The information from the CTD is used in conjunction with multi-beam sonar providing accurate data about the depths of obstructions on the seafloor. The metal frame seen in the picture on the outside of the mechanism is called a rosette.  We attached a rope to the rosette of the CTD, turned it on to collect data, held the devise in the water for two minutes for adjustment, then lowered the instrument down to the bottom of the seafloor. Once the CTD hits the bottom of the seafloor, the rope is pulled back up, the devise is put back into the fast rescue boat, turned off, and it is off to the next location to collect data.  We deployed the CTD in three different locations in the morning and three different locations in the afternoon. At each place where data collection occurred, the location was recorded by using a global positioning system.  Back on the THOMAS JEFFERSON, the information that the CTD collected is downloaded to a computer where specialized software is used to understand the data.

Personal Log 

All of the experiences on the THOMAS JEFFERSON have been interesting and fun.  Tomorrow I will be helping some of the crew on the deck of the ship.  Exposure to saltwater often causes rust to occur; a ship requires constant maintenance!  I am also realizing that this adventure will be over soon, with less than two days left. Until tomorrow…..

A closer view of the CTD.

A closer view of the CTD.

Senior Surveyor Peter Lewit shares the chart used as a guide for the launches to collect data. The red lines in the white area of the chart represent the paths the launches took to collect data using side scan sonar and multi-beam sonar technologies.

Surveyor Peter Lewit shares the chart used to collect data. The red lines in the white area represent the paths the launches took.

Candice Autry, August 15, 2006

NOAA Teacher at Sea
Candice Autry
Onboard NOAA Ship Thomas Jefferson
August 7 – 18, 2006

Mission: Hydrographic Survey
Geographical Area: Northwest Atlantic
Date: August 15, 2006

Crew members prepare the launches to collect data using side-scan and multi-beam sonar

Crew members prepare the launches to collect data using side-scan and multi-beam sonar

Weather 
AM: SW winds 15-20 knots, Seas 1-2 feet
PM: W winds 10-15 knots, Seas 1-2 feet  Chance of showers

Science and Technology Log: Data Collection Begins! 

We have made it to our destination after a thirty-hour journey. It is exciting to get started with data collection, I am curious what is on the bottom of a busy harbor.  After a brief safety meeting that kicks off the morning, we prepare to go out on the launches to begin the process of making a chart that will provide information about obstructions in navigable waters. The teamwork of the crew of the THOMAS JEFFERSON is inspiring to watch, each with a specific duty communicating and working together so that launches are safely deployed.  Today two launches will collect data using side-scan sonar and multi-beam sonar technologies.

The launch is ready to start collecting data. Typically, a launch has a driver, another person to look out for water traffic, and a surveyor who observes the data being collected and who manipulates the computers connected to the "fish" below the launch.

The launch is ready to collect data. Typically, a launch has a driver, a person to look out for water traffic, and a surveyor who observes the data being collected and manipulates the computers connected to the “fish” below the launch.

Bernard Pooser behind the wheel of the launch. The route he drives in the harbor is very specific, and he must follow careful ‘driving lines’ that the surveyor also sees on one of the four computer screens inside of the launch.  This job is much easier said than done, a real challenge!

Bernard Pooser driving the launch in the harbor. The route is very specific and he must follow careful ‘driving lines’ that the surveyor also sees on one of the four computer screens inside of the launch. This job is much easier said than done!

Senior Surveyor Peter Lewit prepares to collect data utilizing side scan sonar. Side-scan sonar provides a picture that shows light and dark images that provide high-resolution images of obstructions on the seafloor.

Senior Surveyor Peter Lewit prepares to collect side scan sonar data, which provides light and dark high-resolution images of obstructions on the seafloor.

The launch I am on today utilizes side-scan sonar, which incorporates sound navigation and ranging that is used for searching for objects on the seafloor. This technology transmits sound energy, which sends a beam from the “fish” (the instrument underneath the launch) that bounces off the seafloor and other objects. Once the sound energy hits the floor, it then bounces back to the fish in the form of an echo. These beams are sent in a fan-shaped pattern that sweeps the seafloor from underneath the launch to approximately 75 meters from either side of the boat (although distances can reach 100 meters).  The strength of the echo is recorded as a “picture” that can be seen on a computer screen.  If there is an object on the bottom of the seafloor, such as a protrusion, the return signal will be strong and will create a dark image on the screen.  If the return signal has a weak return, then the image on the computer will look light.  A tire on the seafloor, or a barge that has sunk is easily seen and depicted! These images are fascinating.

Surveyor Doug Wood observes computer screens where data is being collected. The green triangle is showing multi-beam sonar data.

Surveyor Doug Wood observes computers where data is being collected.

The benefit of side-scan sonar allows for high-resolution of what is on the seafloor. The only drawback of side-scan sonar technology is that the depth of these obstructions cannot be ascertained. Determining the depth of an obstruction is where multi-beam sonar is applied.  Multi-beam sonar utilizes fan-shaped sonar that records depths.  This is done by recording the time it takes for the acoustic signal to travel from the receiver to the seafloor (or object on the seafloor) back to the receiver. The receiver is often referred to as a transducer. The multi-beam sonar transducer is attached underneath the launch.  The combination of side scan sonar and multi-beam sonar create for specific data that can be shared so that navigable waters are safe.

Personal Log: “I have my sea legs!” 

I must admit I was a bit nervous about being seasick!  Our thirty-hour journey was difficult for me for only about three hours, right at the beginning of the trip.  I am very happy for a short experience with seasickness! After getting my sea legs, it is interesting to realize that one can adapt quickly. Often I felt like I was being rocked to sleep as we made our way to our destination through the waves of the ocean. After being on a ship for a couple of days, experiencing land is an interesting sensation. I missed moving around on water and felt as if I were on water even though I was on land! I do not really miss being on land at all.

NOAA Teacher at Sea, Candice Autry, enjoys pudding while taking a break from observing data collection using side-scan sonar. The Statue of Liberty is in the background!

Candice Autry, enjoys pudding while taking a break from observing data collection. The Statue of Liberty is in the background!