Laura Grimm: Echoes and Flares, July 7, 2022

NOAA Teacher at Sea

Laura Grimm

Aboard NOAA Ship Thomas Jefferson

July 4 – July 22, 2022

Mission: Hydrographic Survey of Lake Erie

Geographic Area of Cruise: Lake Erie

Date: July 7, 2022

Weather Data from the Bridge

Latitude: 42 08.7

Longitude: 080 16.9

Sky Conditions: few clouds

Wind Speed: 14.9 knots

Wind Direction: 040 NE

Lake Temperature: 22 ᵒC

Wave Height: 1 ft.

Dry Bulb: 20.6 C

Wet Bulb: 18.6 C

Relative Humidity: 83% (calculated using the following table)

Relative Humidity Conversion Table. Rows: Dry-bulb temperature, ranging from 10 degrees C to 30 degrees C in increments of 1 degree. Columns: Dry-bulb temperature minus wet-bulb temperature, ranging from 1 to 10 degrees C in increments of 1 degree.
Once you know the wet-bulb and dry-bulb temperatures, you can use the conversion table above to calculate the relative humidity.

Science and Technology Log

The mission of a NOAA hydrographic survey is to make bathymetric maps of the floors of bodies of water.  Bathymetry is the study of the “beds” or “floors” of water bodies, including the ocean, rivers, streams, and lakes.  So, what is the difference between bathymetry and topography?  Topographic maps show elevation of landforms above sea level; bathymetric maps show depths of landforms below sea level.

NOAA ships are equipped with lots of different types of equipment to make such maps.  One of these is the Multibeam Echo Sounder (MBES).  It is used to survey large swaths or bands of the floor of oceans and lakes.  This type of technology collects a tremendous amount of bathymetric data.

Multibeam Echo Sounders (MBES) gather information about how deep a body of water is, the physical features of the seafloor, and how close to the surface items like wrecks and obstructions are that might make it dangerous to maritime travel.  Obstructions are things sticking up from the floor.

Multibeam Echo Sounders send out sound energy and analyze the return signal (echo) that bounces off the lakebed, seafloor, or other objects.  Multibeam sonars emit (send out) sound waves from directly beneath a ship’s hull to produce fan-shaped coverage of the seafloor. These systems measure and record the time for the sound energy to travel from the sonar to the seafloor (or object) and back to the receiver. The longer it takes, the deeper the water.  Multibeam sonars produce a “swath” of soundings (i.e., depths) to ensure full coverage of an area. This is sometimes referred to as “mowing the lawn”.  Scientists want to be sure that they don’t miss anything!

underwater, a diver checks out a multibeam sonar apparatus attached to the hull of a ship
Multibeam sonars are secured to the bottom or the hull of the vessel to collect data.

an illustration of a multibeam sonar swath spreading out from the base of a NOAA ship (above the water), revealing the modeled bathymetry of the seafloor (below the water)
MBES Data showing seafloor topography

Multibeam Echo Sounder (MBES) showing bathymetric data, also known as, seafloor topography.  Bathymetry is the study of the “beds” or “floors” of water bodies, including the ocean, rivers, streams, and lakes.  Topography is a detailed description or representation on a map of the natural and artificial features of an area.

modeled bathymetry shows a small boat resting on the seafloor.
Small wreck found using multibeam sonar.

When looking at a hydrographic image, keep in mind that blue = deep water, red = shallow water.

view of a small boat mounted on NOAA Ship Thomas Jefferson; the hull is visible
This is one of the launches (small boats) that is used to collect hydrographic data close to shore.  A Multibeam Echo Sounder (MBES) is attached to the hull (bottom) of the boat.
close-up of the multibeam echosounder mounted on the hull of the small boat
The black and red piece of technology is the MSEB
close-up of the multibeam echosounder mounted on the hull of the small boat; it looks like a black box with red panels
A close up of the MBES that is secured to the hull of the launch.

The red rectangle in the foreground is the transmitter.  It sends out the sound energy.  The other red rectangle is the receiver.  It “hears” or receives the echo of the sound.  This information is then sent to a computer that analyzes how long the echo took and then calculates the depth. 

The small silver latch-looking piece of equipment is the sound speed indicator.   It calculates the actual speed of sound in the conditions under which the measurement it taken.  A “ping” is sent out from one end and is received at the other end.  The speed of sound is then calculated. 

I always thought that the speed of sound was a constant number.  I guess not!  So why is calculating the speed of sound so important?  The speed of sound in water is affected by the temperature and salinity of the water.  The warmer the water, the faster sound energy travels.  Once a molecule starts to vibrate, it passes this energy on to the next molecule, and to the next, and so forth.   Water molecules in warmer water are moving quicker so sound energy transmits faster; cold water is more dense and therefore the sound transmits slower.  The colder the water, the slower sound energy travels.

Salinity also affects the speed of sound.  Salinity is the measure of dissolved salts in water. This accounts for all salts, not just sodium chloride (table salt).  The salinity of fresh water is very low compared to that of the salt water in the oceans.  Water that has a lot of salts dissolved within will transfer sound energy more quickly.  Electroconductivity is a measurement of salinity.  (Students – you may remember that we use an electroconductivity probe to help us understand how much fertilizer is in the water used to grow plants hydroponically in the greenhouse.)  Knowing the speed of sound in water helps hydrographers interpret the data from the MBES more accurately.   

Something to think about . . .

How is a Multibeam Echo Sounder like and unlike echolocation that is used by bats?

For the little Dawgs . . .

Q: Where is Dewey today?  Here is a hint.  It is also called the “front” of the ship.

Dewey, a beanie monkey, sits on a white surface with water in the background
Where is Dewey today?  Here is a hint.  It is also called the “front” of the ship.

A: Dewey is on the bow of the ship.  “Bow” rhymes with “cow”. 

a view of the ship's bow with the beanie monkey perched on a rail
Do you see Dewey? He is sitting on the bow of the ship.

Dewey is sitting on the bow by the Jackstaff (flagpole).  The Jackstaff is a flagpole that flies a maritime flag called the Union Jack of the United States whenever it is at anchor or in port.

50 white stars on a blue background
Union Jack of the United States. Just the stars and not the stripes.


Laura on the bow, with Dewey the beanie monkey perched on her shoulder. Laura is wearing a Teacher at Sea hat. we can sea the anchor behind her.
Dewey and I are enjoying the fresh air on the bow.

Personal Log

We had fun last evening.  Patrick, a Seaman Surveyor, told us that he had several flares that had expired.  Instead of throwing them away, he decided to have us light them.  What a great thing to do around the 4th of July!

  • a seaman holds a lit flare toward the fantail
  • Laura preps a flare
  • Laura holds lit flare over the edge
  • Laura and lit flare
  • Two other crewmembers hold lit flares over the edge
  • A crewmember holds a lit flare over the side of the ship
  • Several crewmembers holding lit flares; orange smoke billows out
  • Two crewmembers shoot small flare guns into the air
  • Laura points a flare gun into the air; Patrick instructs
  • Laura fires flare gun

Because we were surveying near Lake Erie, we had the opportunity to watch the 4th of July fireworks over Cleveland and surrounding communities. Such a lovely way to spend Independence Day.

Around 2300 (11:00 p.m.) we started to transit (move) toward Erie, PA. It’s been a good day. I look forward to waking up in the waters near Presque Isle.

Erica Marlaine: Happy Fourth of July from the 49th State, July 4, 2019

NOAA Teacher at Sea

Erica Marlaine

Aboard NOAA Ship Oscar Dyson

June 22 – July 15, 2019

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Gulf of Alaska

Date: July 4-5, 2019

Weather Data from the Bridge:

Latitude: 55º 48.9 N
Longitude: 159º 2.3 W
Wind Speed: 4.2 knots
Wind Direction: 186.5º
Air Temperature:  14.7º Celsius
Barometric Pressure: 1022.12 mb
Depth of water column 84.5 m
Surface Sea Temperature: 10 º Celsius


On March 30, 1867, Secretary of State Seward purchased Alaska from the Russian Empire for 7.2 million dollars (or 2 cents per square mile). It was deemed a territory for many years until January 3, 1959 when President Eisenhower signed a proclamation admitting Alaska into the United States.  The word “Alaska” comes from an Aleut-language idiom that means “object to which the action of the sea is directed.” It is the northernmost and westernmost state in the United States. It is also the largest state.  By comparison, it is twice the size of Texas.

Celebrating the Fourth of July, NOAA style

My usual Fourth of July at home includes a bar-b-que, swimming, and attending a fireworks show at night. The Fourth of July celebration on the NOAA ship Oscar Dyson was completely different, and literally a BLAST.  At noon, an announcement was made for “all hands” to report to the galley for Fourth of July “mocktails” or fun non-alcoholic drinks.  (There is no alcohol on a NOAA ship.) I had a delicious “mimosa” made of orange juice and sparkling cider. Later, we were taken on a wonderful ride past Mitrofania Island. 

Approaching Mitrofania Island
Approaching Mitrofania Island
Mitrofania Island
Mitrofania Island

Photographs do not do it justice.  It was my first time up on the fly bridge (the “roof” of the boat) and I loved being able to take in the 360 degree views.  Many people never get to see this part of Alaska as it is not a route commonly taken by cruise ships. The “fireworks” part came the next morning, when “all hands” were again called to the deck to light off expired flares.  While some made a popping noise, the one I did produced thick orange smoke for at least 30 seconds. It was, as I said, a literal blast!

Science and Technology

Later, we were back on the bridge but for a sadder reason. A dead whale was floating in the water right near the boat.  I asked if anyone comes to pick up dead whales.  It was explained to me that if a dead whale washes ashore, it will be picked up and taken for a necropsy to see if the cause of death could be determined.  However, if they are at sea, they will be left to decompose and become part of the sea once again.

Whale carcass
Whale carcass

On a happier note, I was sent to the bridge later in the day to see if there were any whales in the vicinity as we do not fish if whales are nearby. It turned out that there were 5 whales in the distance (but close enough to see with binoculars). Whales are somewhat easy to spot as they must come to the surface often to breathe. When they exhale, they produce a spout of moist air from their blowhole.  Since different species of whales produce different shape or size spouts, the spout is one way to identify the type of whale you are seeing. Other identifying features are size, color, fin shape, and whether they are alone or in a group. Some whale species travel in groups or pods, while others are more solitary. For example, killer whales (which are really dolphins) spend much of their time in large groups that travel and hunt together. Sometimes 4 generations of killer whales will be found together.  In contrast, humpback whales are more often found alone or with their calf.

Whale Fun Facts

While many people think that whales spout water, it is actually mostly air.  The spout is their exhale. Since they are mammals, and not fish, they do not have gills, and must come to the surface to breathe through their blowhole.

A baby whale is called a calf.

A group of whales travelling together is called a pod.

The blue whale is the largest animal in the world. It can grow to be as long as 3 buses, and its heart is as big as a car. Despite being so large, blue whales eat some of the smallest marine life, such as the krill discussed in an earlier blog.

A blue whale’s call is so loud, it can be heard underwater for hundreds of kilometers.

Whales are warm-blooded, so they need to develop a layer of fat (called blubber) to stay warm in cold water.

Whale blubber experiment for parents and kids to do together

Make a blubber glove by filling 2 ziploc-type plastic bags with shortening (such as Crisco) and taping them together to form a pocket.

Fill a bowl with water and ice cubes.

Allow your child to quickly touch the cold water in the bowl with their bare hand.

Then have your child put his or her hand in the blubber glove, and then put their gloved hand into the cold water.


Stephen Tomasetti: Sharks of the Gulf, August 24, 2014

NOAA Teacher at Sea
Stephen Tomasetti
Aboard NOAA Ship Oregon II
August 11 – 25, 2014

Mission: Shark/Red Snapper Longline Survey
Geographical Area of Cruise: Gulf of Mexico
You can view the geographical location of the cruise here at anytime:
Date: Sunday, August 24, 2014

Weather Data from Bridge:
Air Temperature: 31.5 Degrees C
Water Temperature: 31.1 Degrees C
Wind Speed: 7.88 Knots
Barometric Pressure: 1009.4 Millibars

Science and Technology Log:

Today I’ll walk you through the sharks and other fish we’ve caught along leg two of the NOAA Oregon II longline survey. Unfortunately, due to red tide, many sharks had moved out of the areas we were in, so we caught substantially less sharks than usual. But, we still caught quite a few. Check them out:

Atlantic sharpnose
Atlantic sharpnose shark

Name: Atlantic sharpnose shark

Sci. Name: Rhizoprionodon terraenovae

Description: These sharks are very common both inshore and offshore. They often have white spots along the side. You can also tell them by their long labial furrows (grooves around the mouth).

Scientist Andre Debose and volunteer Sarah Larsen work up a blacktip
Scientist Andre Debose and volunteer Sarah Larsen work up a blacktip shark

Name: Blacktip shark

Sci. Name: Carcharhinus limbatus

Description: These sharks can be pretty feisty. They are surprisingly strong (even the little ones). You can identify them by the black marking on the tip of their pectoral fins and the lower lobe of their caudal fin.

Scientist Michael Felts with a Florida smoothhound (photo cred: Joan Turner)
Scientist Michael Felts with a Florida smoothhound (photo cred: Joan Turner)

Name: Florida smoothhound

Sci. Name: Mustelus norrisi

Description: These are my favorite sharks that we’ve caught. They are beautiful. They have small, blunt teeth and are missing a precaudal pit (before the caudal fin). They are long sharks, with second dorsal fins that are very large.

A young tiger shark
A young tiger shark

Name: Tiger shark

Sci. Name: Galeocerdo cuvier

Description: These sharks are known for being fierce hunters and apex predators. They are beautiful sharks with dark spots/stripes along the sides and dorsal fin. They can reach over five meters!

Sandbar shark
Sandbar shark

Name: Sandbar Shark

Sci. Name: Carcharhinus plumbeus

Description: We caught a lot of these sharks on our shifts. They were generally pretty large and we often had to use the cradle to get them close enough to take their measurements. One way to tell sandbar sharks is by their large dorsal fin.

A parasite pulled of the anal fin of a sandbar shark
A parasite pulled off the anal fin of a sandbar shark

For all the sharks we catch, we generally take length measurements, mass, sex and a fin clip/tissue sample (to look at genetic population structure). Then the shark is tagged with a tag and tossed back in the water. Occasionally, NOAA uses a satellite tag on sharks if they want to get additional data. On this cruise the night watch tagged a hammerhead shark with a satellite tag. This particular tag will transmit information when the dorsal fin breaks the surface of the water (often hammerheads and tiger sharks are tagged with these tags because they occasionally come up to the surface).

Personal Log:

Well we’re through fishing for this leg of the survey. We arrive back in Pascagoula, Mississippi tomorrow morning. There’s a lot to miss aboard the Oregon II. Below is a list of the top 5 things I’ll miss about life on the ship (in no particular order).

5) The Food: Three delicious meals a day. I’m not going to know what to do when I return to New York City and have to cook my own food again. Mac’ n cheese. Captain’s Platter. Eggs Benedict. Ice cream every night. I’ve been spoiled.

Second Chef Mark Potter hard at work
Second Cook Mark Potter hard at work

4) The Crew: I spent the majority of my time with the “day shift,” of scientists and fishermen. We would spend basically 11am-2am every day together. We’d eat together. Work together. Hang out between sets together. And finally watch movies together after shift.

The day crew pictured at night
The day crew pictured at night

In addition to the day shift there is an entire crew of interesting people I’ve spent time with: the NOAA Corps Officers, the Engineers, the Night Shift, and the Stewards. It takes a large crew to keep this ship running.

3) The Open Ocean: Picture cruising alongside dolphins at sunset, flying fish cutting through the water, a breeze on deck, and nothing but open ocean until the horizon line.

A flying fish jumped aboard
A flying fish jumped aboard

2) The Fishing: Before this trip it’d been a while since I had been fishing. I’ve never fished using longlines until the Oregon II. I learned a lot about fishing. Check out my earlier blog post here for more on that.

1) The Marine Life: You’ve already read a lot about some of the fish we caught. Here are more photos!

Volunteers Samantha Ehnert and Kelly Korvath kissing sharpnoses
Volunteers Samantha Ehnert and Kelly Korvath kissing Atlantic sharpnose sharks

Red Snapper
Red Snapper

Today, on our way back to Pascagoula, we stopped for a while to test the emergency equipment. In case of an emergency, there are a variety of lifesaving resources to utilize. We shot off flare guns, smoke signals and line casters. I shot off a line caster which slightly resembles a rocket launcher that shoots a rope to another ship in the case that we’d need to get to them. It was sort of like the Fourth of July!

Lieutenant Commander Eric Johnson shooting off a flare
Lieutenant Commander Eric Johnson shooting off a flare

Did You Know? Japanese warriors used to use dried shark skin for the handles of their swords, to keep them from slipping out of their hands.