tidal gauge – NOAA Teacher at Sea Blog

September 21, 2011April 28, 2021

Kaci Heins: September 19-21, 2011

NOAA Teacher at Sea
Kaci Heins
Aboard NOAA Ship Rainier
September 17 — October 7, 2011

Mission: Hydrographic Survey
Geographical Area: Alaskan Coastline, the Inside Passage
Date: Wednesday, September 21, 2011

Weather Data From The Bridge

Clouds: Overcast
Visibility: 4 miles
Wind: 20 kts
Waves: 0-1 feet
Temperature
Dry Bulb: 11.7 degrees Celsius
Barometer: 1000.1 millibars
Latitude: 55 degrees North
Longitude: 133 degrees West

Science and Technology Log

Today was the first day that the survey launches left the Rainier to install and recover benchmarks and a tidal gauge. The weather was not great and the crew had a lot of work to do so I was not able to go with them this time. A benchmark is a small brass disk with information inscribed on it that relates to the station it represents. The benchmark holds the height of the datum. The purpose of setting a tide gauge is to measure the water level. The water level information is used to reduce the bathymetric data acquired to the chart datum (mean lower-low water, MLLW). Finding benchmarks has become quite popular through the hobby of geocaching. This is where participants use latitude and longitude within Global Positioning Systems (GPS) as a way to hunt down “treasures” hidden by other participants. This also includes finding benchmarks.

I’ve been trying to head up to the bridge as much as I can to learn as much as I can during this Teacher at Sea experience. The first time I went up at night I had no idea about the environment that the officers work in on the bridge. At night the officers on the bridge actually work in complete darkness. All of the computer screens have dimmers or red filters so that the least amount of light affects their eyes in the darkness. The reason it is so dark is because the officers need to be able to see the lighted navigation buoys to stay on course and to spot the lights of other ships that are heading in our direction. There are also one or two deck personnel that are lookouts either on the flying bridge or bow to keep watch for ships, lights, and other objects that could potentially be a hazard to the Rainier. A flying bridge is usually an open area above an enclosed bridge where the ship’s officers have a good view of everything around the front and sides of the ship. We are traveling through the Inside Passage off the Southeastern coast of Alaska, which is extremely narrow in some places along the way. This means that it is very important that the officers know exactly where they are and what is around them.

Personal Log

I have been able to do some other neat tasks on the ship while the majority of the crew were out on their launches. We finally were able to find a place to anchor at Ulloa Channel because we had a good “bite” with the anchor–it is protected somewhat from the weather we are dealing with, and it is close to our tide station. They also let me run out some chain for the anchor and I was able to practice using the crane on the ship. However, the best part so far has been being at the helm, or the steering gear of the ship. I will admit I was pretty nervous the first time I grabbed the wheel because it was at night so I couldn’t see hardly anything. Today, the officer of the deck (OOD) let me at the helm again because we were in open water. When I am at the helm I have to watch my gyro-heading, which shows me true North, and my magnetic compass, which is more of a back up if the electronic gyro-heading fails. If I have a heading of 150 then I have to make tiny adjustments or corrections to try and stay on or close to that number as possible. Even when I make the tiniest adjustment I can see how much the ship moves. I did start getting the hang of it and one officer even said he had never seen a visitor do so well!

One other item that I will mention in this blog is that the weather in Alaska during this time of year is overcast, rainy, and cold.

Canada — Beautiful Scenery Along the Inside Passage

However, going into this I had an idea of what to expect and I enjoy the fact that I get to see the non-glamorous side of this type of work. It does not matter if it is rainy, cold, what you are wearing, or what you look like because there is a job to do. It has been overcast every day, but the pine trees are amazing shades of green and the pictures do not do them justice. We have also had 15 foot waves and 115 knot wind (this is the same as a category 3 hurricane!). The wind didn’t bother me as much as the waves did. I thought it was fun for the first 30 minutes, but then I had to lie down for a while because I wasn’t feeling too well. I never threw up, but it did become uncomfortable. Now that we are anchored and have stopped moving I feel funny because my body has been used to moving around so much for the past three days. I sure hope I don’t get land sickness when I am done with this cruise!

Student Questions Answered: Here are student questions answered about feeding so many people on a boat over 3 weeks time.

Animals Seen

Puffins

Questions of the Day

We experienced 115 knot winds Monday night. What category hurricane would that be the equivalent to? Use the website if you need help.

http://www.nhc.noaa.gov/sshws.shtml

June 8, 2009April 5, 2021

Susan Smith, June 8, 2009

NOAA Teacher at Sea
Susan Smith
Onboard NOAA Ship Rainier
June 1-12, 2009

Mission: Hydrographic survey
Geographical area of cruise: Trocadero Bay, Alaska; 55°20.990’ N, 33°00.677’ W
Date: June 8, 2009

Weather Data from the Bridge
Temperature: Dry Bulb: 13.9°C (57°F); Wet Bulb: 12.2C (54°F)
Cloudcover: Overcast 8/8
Wave Height: 0-1
Visibility: 10 nautical miles
Wind: 325, 4 kts.
Sea Wave Height: 0-1
Sea water temperature: 12.2°C (54°F)

Science and Technology Log

Before I explain the science we did today, I will answer the question posed on log number 3: What is a patch test and why is it run? A patch test is used to find offsets in sonar setup (continuous errors) and timing errors. It is done whenever physical alterations occur with the sonar. Such problems can occur when it is mounted skewed, or not in perfect line with the ship.

The Patch Test checks pitch, roll, and yaw. The ship is run out from the shore and back into shore, along the same line. The computer has all offsets set to zero. A swath is sliced at the edge so the computer is looking at the outer beams from the side. With a roll offset it must be changed from an X pattern to a single, flat line. With a pitch offset, a nadir view is taken, the angle is adjusted until the two lines (one out from shore, one into shore) form a single straight line. Yaw also has two lines offset so they must be combined to one line configured identical to the two lines. The Patch Test takes approximately one to two hours to complete.

Today I was involved in obtaining data relevant to tides. We used a tide gauge, levels, GPS, and a staff placed in the water, with a nitrogen being pumped under it. The tide gauge measures the unit of pressure it takes for a nitrogen bubble to be squeezed out. The greater the amount of water covering it the greater pressure is required to release a bubble. To get water depth, someone reads the staff water level and continually records this information for three hours. This will enable us to know the difference in the pressure gauge readings and the staff water level. A Global Positioning System (GPS) is used to determine where the staff is by getting a good constellation (satellites in orbit) reading.

It was my job to hold a level rod on the primary benchmark location while someone else recorded measurements using the surveyor’s level (The level rod is measured in centimeters). The surveyor’s level has three lines, or stadia, inside the level. These lines are read as upper, middle, and lower. I placed a smaller bubble level against the rod to make sure it was straight up and down. Once my location was recorded a second person, also holding a level rod, placed hers on a staff (a triangular wood structure) set in the water. The surveyor’s level was disturbed, then a second reading was taken at the staff, and a second reading was taken at my benchmark. If the numbers did not match within a certain range, or historical data, the measurements had to be repeated.

We went through this process for five benchmarks. These benchmarks were placed in specific locations based on elevation and stability of the ground above high tide level. This procedure is completed to ensure the benchmarks and the staff have not been moved, by either human disturbance or a natural occurrence, such as an earthquake. As a side note, in some locations these benchmark rods have had to be drilled down 125 feet. In the Arctic they may be drilled 25 feet into the permafrost. When drilling the holes for the benchmarks care must be given to ensure the surface is smooth, not skewed, or at an unusual angle.

Sometimes a temporary benchmark, called a turtle, must be used. This is a small, heavy, circular piece of equipment, which can be placed anywhere solid. The person holding the staff can turn all the way around it to allow for different measurements. All data collected in this activity are sent to NOAA’s tides office.

Personal Log

After viewing the ship’s photography server I have become interested in what actually goes on in the dry dock. The dry dock is in Seattle where the ship goes for repairs, restoration, and refitting. After the launches and other things are removed from the ship it goes to the dry dock. Gates close off the ends. On the floor of the dock are blocks for the ships hull to sit on, placed exactly in line for this particular ship. Divers go down to check for precise placement before the water is drained. The ship is tied to the dock to stabilize it (prevent it from tilting or falling off the blocks) and if you are not off the ship before it goes into dry dock you are not getting off anytime soon! On the hull are numbers used to identify the ship’s sections. When it is being retrofitted the workers must know where each section came from so the ship can be put back together correctly.

Tape where the symbol and number were painted

Underside of ship on the blocks; the black hole is on for anchor storage

Dry dock operations can take from two months to over a year, depending on the work needing to be done. Crew stays on board as long as possible. When berths are being refurbished they stay in local hotels. Other personnel either work on other NOAA ships or go to other project sites. (All dry dock photographs courtesy of Rainier picture server)

For more information visit these sites:

http://www.osha.gov/SLTC/shipbuildingrepair/drydocking.html http://en.wikipedia.org/wiki/Dry_dock (has history of ancient dry docks)

August 20, 2008April 5, 2021

Patricia Donahue, August 20, 2008

NOAA Teacher at Sea
Patricia Donahue
Onboard NOAA Ship Rainier
August 19-23, 2008

Mission: Hydrographic Survey of Bear Cove, AK
Geographical Area: Kachemak Bay, Alaska, 59.43.7 N, 151.02.9 W
Date: August 20, 2008

Weather Data – Glorious!

Science and Technology Log

A black bear comes to inspect what the land party is up to!

WOW! That says it all. Today’s big excitement was supposed to be the leveling of the tidal gauge and the survey work in the cove. The bigger thrill – and scare – was the bear that approached to within 30 feet of me as I was standing over a benchmark with a leveling rod. Remembering the safety rules about bears, I stayed calm and alerted the others. Then I put down the pole and walked away slowly. Fortunately it was a young and smallish black bear who was easily scared off by the Commander throwing rocks. We were all on our guard the rest of the day. There were several benchmarks to check. Some of the climbing was perilous. All of the work had to be done at low tide. The survey data was collected and I look forward to seeing what’s done with it.

During the afternoon, another emergency drill took place and I was invited to watch. In the scenario, the bridge lost the ability to steer the ship. Control of the vessel had to be made from aft steering, below decks where the rudders protrude from the vessel. By using only a compass and steering orders given in degrees, the helmsman maneuvered the ship. There were no windows or other indicators of the ship’s position. To make matters worse, the scenario called for a loss of communications so a sound powered phone that uses only the energy from the speaker’s voice to operate had to be used instead.

By late afternoon the ship moved to its new anchorage a few miles from Homer. I was invited to watch the lowering of the anchor. The anchor weighs 3500 pounds and there are two of them. Each length of chain weighs 1200 pounds and there are a total of 12 lengths for each anchor. Today we used only 5 sections of chain and 1 anchor. Each section of chain is 90 feet (15 fathoms) long. The anchor is lowered while the ship is in reverse.

Personal Log

My family and my students enjoy a game called geocaching. We’ve started by using hand held GPS devices to find benchmarks and eventually we’ll move on to finding caches and creating our own. I’ve only ever seen old benchmarks but today I saw brand new ones. One of the officers even showed me how they’re made. Benchmarks indicate the exact location and height above sea level of that particular place. The Chief Steward took me to see the food storage facilities. The freezer is enormous! The ship carries enough food to last for 6 months, although the fresh fruits and vegetables only last for one month. They have more food than CostCo!

Animals Seen Today

Stellar’s Jay, Black Bear, and two species of Jelly Fish

Question of the Day

How long is the anchor chain on the Rainier? Provide your answer in feet and fathoms. How much do the anchors and the chain weigh altogether? Why is the boat in reverse when the anchor is dropped?

Challenge Yourself

Go to http://www.geocaching.com and type in your zip code. Identify a benchmark near your home. Find it and take a photograph!

June 16, 2008April 2, 2021

Mark Friedman, June 16, 2008

NOAA Teacher at Sea
Mark Friedman
Onboard NOAA Ship Rainier
June 8-20, 2008

Mission: Hydrographic Survey and ocean seafloor mapping
Geographical Area: Southeast Alaska
Date: June 16, 2008

Here I am studying nautical charts as preparation for the Tidal Gauge expedition.

Science and Technology Log

Each day the RAINIER’s “Ship’s Officer,” in collaboration with the field operations officer and the ship’s commander, issue a “Plan of the Day” also known for short as the POD. (Who knows what marine animals move in groupings called a POD? First one to reply from Los Angeles gets a free Alaskan souvenir!) The POD contains important information such as, for Sunday, June 15, Sunrise was at 0415 (4:15 am), and sunset is at 2139 (9:39 pm!) It will be a long day! I rise at 6 am to read the POD and find my assignment.

POD Revelations
The ship’s position is: Anchored, Palisade Is., AK. The POD also has tide levels, U.S. Coast Guard beacons in the area, the weather, and who the officer on duty is. The weather you ask? How important, especially because many of us are going out on launches and the smaller skiffs for specific assignments. The launch drivers need this especially to make sure all operations are safe. The winds are mild, coming in from the south at 5-10 mph, cloudy with showers, air temperature a balmy 51F with seas of 1-2 foot waves.

The POD has major assignments for anchor watch and officers on duty. Safety is a constant refrain as there are anchor watch positions around the clock to staff the bridge (command center) sending regular weather reports to the Coast Guard and National Weather Service and maintaining a secure and safe environment. The POD also lists all the assignments for the launch vessels being dispatched by the mother ship—no not Battlestar Galactica or the Enterprise, but the RAINIER. Today two vessels will be doing sonar readings around San Christoval Channel and North San Fernando Island. The other two, one of which I will be on, is going to remove a tide gauge and do a recon (reconnaissance) mission for a new tide gauge location.

The Journey Begins

Here I am learning to withstand the cold in my Arctic survival suit.

7 am- We are all up for a hearty breakfast, made by three talented chefs (especially in the omelet, soup and dessert department).

7:30am- I struggle into my arctic survival suit and boots in preparation for a “wet landing.” I feel like Sylvia Earle in her “Jim Suit” as I waddle like a penguin to the stern of the ship to board a skiff for an hour journey up narrowing channels and over rapids to reach our destination. (I have put on all layers of clothing that I brought with me from Los Angeles, preparing for frigid temperatures and lots of wind and mist en route.)

8:30 am- With a spraying salt mist and a wind chill factor making the temperature about 20 degrees Fahrenheit, we race up the labyrinth of islands and channels to our destination. A deer and her fawn stare blindly at us on our port side, a humpback whale breaches on our starboard. We even glimpse a couple of sea otters playing/rafting in the kelp.

On Location
9:30 am- We have reached the tide (marine), or water level, gauge. Our assignment is to remove it after ensuring calibrations have been correct. The tide is coming in and the shore is covered with algae, mini-white barnacles, a sprinkle of clams, a species limpets and small purple mussel beds which are thriving.

What is a tide gauge and why are they important?
Water level gauges are instruments to measure water surface elevation over long and short durations of time. They have been used for centuries by mariners to improve their knowledge on the depth of water and apply this information to the chart. This information can aide in the calculation of tidal currents, the ebb and flow of water as the tides change. More modern gauges need a power supply to relay information via satellite to appropriate organizations interested in this data.

A tide gauge consists of a number of instruments including, foremost, a measured, calibrated staff that is securely mounted into rocks to give a visual baseline of water levels. It is connected to benchmarks by using a survey instrument called a level, which optically measures height differences on a survey rod, which I held during the operations. Benchmarks used by NOAA, and previously by the U.S. Coast and Geodetic Survey, are brass survey discs (see photo right) that are imbedded into bedrock and stamped with a code that correlates in NOAA data banks to date of installation, project, location number, etc. Five of them are traditionally imbedded at various locations in the vicinity of the staff. They are leveled between each other and the staff, establishing a mathematical correlation. Gauge measurements are all related to the benchmarks, which hold the permanent datum for the tide station.

The Underwater Component

NOAA divers retrieve a submerged tidal gauge

Another component of the gauge is an orifice (brass pipe with an open end) that is placed where it is continually submerged. It is connected to an electronic readout instrument via strong plastic tubing that is filled with nitrogen. As the gas comes under more or less pressure, based on the pressure exerted by the quantity of water pressing down upon it (water pressure), it registers the height of water levels. (Similar to how air pressure is registered by a barometer, a little remembered instrument but critical to meteorological forecast and studies).The information on depth is thus recorded and electronically transmitted out of the area thru solar powered equipment. In addition to water levels for meteorological (weather) purposes, over time these tidal gauges, when coordinated with others and register actual sea level rise which is now occurring more rapidly due to glacial melting from global warming. They have also been used to register tectonic plate movements. We disassembled the land equipment after completing our benchmark surveys. Later we scouted for a new location further south for a new tidal gauge and benchmark installation site. Then the divers went into action (see above photos). Their job was to retrieve the submerged gauge and piping for future use. In the process they took a video of part of the undersea flora and fauna.

Back on the Ship

All equipment is secured, checked and prepared for the next installation site. The gauge team tomorrow will secure benchmarks for the establishment of a new tide gauge station. (Guess what? At the installation site they found a 1927 benchmark still intact and functional!!)

A sun star, a type of sea star, was observed during the tidal gauge dive.

July 27, 2007April 1, 2021

Ginger Redlinger, July 26–27, 2007

NOAA Teacher at Sea
Ginger Redlinger
Onboard NOAA Ship Rainier
July 15 – August 1, 2007

Mission: Hydrographic Survey
Geographical Area: Baranof Island, Alaska
Date: July 26–27, 2007

Weather Data from the Bridge
Visibility: 10 Nautical Miles
Wind directions: 110°
Wind Speed: 10 Knots
Sea Wave Height: 0-1 feet
Seawater Temperature: 14.4° C
Sea level Pressure: 1012.9 millibars (mb)
Cloud cover: Cloudy
Temperature: 16.7° C, (62° F)

Mariner Word of the Day: Scuttlebutt. A scuttlebutt on an old sailing vessel was the barrel where drinking water was stored. People would gather and talk casually, or gossip, as they drank water. This led to the second definition of scuttlebutt, “a rumor.”

ENS Pereira, Divers-Physical Scientist Campbell and LT Yoos, Coxswain O’Connor review safety checks and dive plan.

Science and Technology Log

We moved the ship from Steamboat Harbor to Bocas de Finas near Bush Top Island because winds were picking up. The ship is safer when it is not anchored in a high wind area! Weather matters a great deal when you are working on the water. Winds contribute to sea waves, swell heights, and can create less-than-ideal conditions for hydrographic surveying. Weather is taken into account in planning when, and where the ship will travel to work. It also determines what should be done first. Specifically, determining the day’s priorities can depend on what time the winds and seas are expected to change. While seaworthy vessels can work effectively in rough waters as is sometimes necessary, knowing when the water will be rough makes for better planning. What I have come to appreciate on this ship is the accuracy of the weather predictions aboard the RAINIER. If the Orders of the Day (OOD) read that it is going to rain – it rains. If it tells me that there will be swells in the afternoon from 3 to 4 feet – there are! Now I don’t know about you, but I have noticed when I am at home the only accurate weather forecast I get is when I look out the window.

What is it about the weather information that is used on board that makes it so reliable? First, there are many sources of information about the weather that are available, and second, they use them! The Officers on board know a great deal about the earth, from surface to upper atmosphere, so they know what information is necessary for a good analysis. There are many resources available to the RAINIER that you can access too. For example, there are text-based discussions of the weather based on the use of different global models, there are local forecasts, there are infrared satellite maps updated every 30 minutes so you can see where clouds are forming and how they are moving, there are also satellites that collect data in order to show the visibility spectrum, or how much light is available –every 30 minutes. (It tells you the amount of radiant-light energy entering the area.) Another is QuickSCAT that creates a chart of the wind’s movement in an area (with lots of small arrows) so you can see exactly what directions it is moving (wind swirls and moves like water around rocks – it doesn’t just go in one direction all the time!). Lastly, there are grids that tell you the extent of high and low pressure systems, how strong they are, and where they are likely to move. Pressure systems impact the direction of the winds, and their strength.

Sporting Goods - Craig, Alaska — Sporting Goods – Craig, Alaska

With all of this information, you can take into account many variables that affect navigation: visibility, wind speed and direction, cloud cover, precipitation (which also impacts visibility), water movements, (direction and speed of waves, and swells). I should also add a non-weather related variable that impacts planning – tides. Considering all these variables together helps predict conditions in order to choose the best time of day to complete work, and move vessels through the water SAFELY! As everyone starts their day they know what to expect so they are well prepared.

Website for weather information related to the RAINIER’s work (thanks to CO Noll):

Marine Forecasts Homepage
Offshore Forecast for Southeast Alaska
National Weather Forecast Discussion Page (with glossary hyperlinks):
Coastal Zones of Southeast Alaska
GOES Infrared satellite (good for clouds)
GOES Visible spectrum satellite (good for sun)
British Columbia forecasts
QuickScat (Wind direction and speed)

And graphics:

Pacific Profiles – Predictive Charts
Local Higher-resolution grids (experimental)

Survey Tech Krynytsky and ENS Villard-Howe (Navigation Officer) gather and examine bottom samples.

Yesterday’s work

Tide Gauge check – Nossuk Bay. We traveled to Nossuk Bay to inspect a Tide Gauge, as it was not sending data correctly. Tide gauge inspections require SCUBA (Self Contained Underwater Breathing Apparatus.) The divers were going to 40 feet below the surface. The pressure is greater underwater every 33 feet, so it is harder to move and to breathe. A specialized crew is sent for this job since it requires specific training in order to execute perfect communication, keen observations, and precise movements of the boat.

After ensuring the underwater section was working properly attention shifted to the land-based components. The crew, except the coxswain, went ashore to inspect the rest of the equipment. Since we noticed fresh bear sign in the area, we talked loudly and kept our eyes open. After everything checked out ok we returned to the ship. I had fifteen minutes to eat lunch and return to the boat for sediment surveys and a run to Craig, AK to pick-up two officers joining the RAINIER for the trip back to Washington. One is a Junior Officer returning to the RAINIER for the trip back to Sand Point. The other is the new Commanding Officer, who will be replacing CO Noll. CO Noll’s commission with the RAINIER ends with the completion of this journey.

Checking the transmission equipment to ensure it is working properly.

We gathered samples from seven different locations where ships and boats anchor when they enter Boca de Finas. Knowing the bottom type can ensure safe anchorage. Not knowing what the bottom is made of when you drop anchor can be dangerous. Surveying the bottom consists of dropping a line with a scoop to the bottom, and examining the contents once the sample is back on board. The contents are compared to a descriptive chart to be sure the correct classification is selected. This information will appear on NOAA charts to help navigators in this area.

Personal Log

The crew jests that the official footwear of Alaskans is a boot called XTRA TUF. When in Craig, we stopped in at the local sporting goods store and I noticed how neatly arranged everything was – with one exception – the boots in the picture below. I asked the man behind the counter about this and he said, “The contents of those boxes will be gone in the next 48 hours – so we don’t bother to mess with them. So I think the crew is correct. At about 10:00 last night, I asked ENS Villard-Howe some questions about ropes, navigation & direction vocabulary. We started to talk about all sorts of nautical topics. She went to her cabin and brought me three very important books – her top three if you want to know anything about maritime topics! The Eldridge Tide and Pilots Book (first written in 1854), American Merchant Seaman’s Manual, and The Ashley Book of Knots. (If anyone wants to get me books for my classroom – these are the three on my wish list! Young potential mariners and marine scientists can learn a great deal from them! )

We talked for another forty-five minutes. As we started to yawn in between sentences we said “enough.” (It wasn’t the company or the topic we were exhausted.) I have to admit, I felt like I was talking with someone who knows and loves the history, knowledge, and skills of her work. She has a true passion for maritime work and her work on the RAINIER.

For my students, I wish them the same level of passion for their endeavors and appreciation for the contributions and history in their yet-to-be chosen field. It is this kind of dedication that makes a great worker, teammate, and leader. There are many examples of this on board – I just happened to spend the later part of the evening exploring the depth of knowledge of one crewmember!

Personal milestone – Sea legs: I ate greasy-yummy pizza on the way back from Craig, AK (a small port town on Prince of Wales Island), while bouncing and rocking across 2-3 foot swells for an hour and it didn’t bother me one bit! : )

Question of the Day

Topic 1: What websites can you use to learn about tomorrow’s weather in your area? (Start from the ones that are listed above, and see if you can’t find the links from the SE Alaska sites to your local information.) What information is used to forecast weather in your area? Using the information on the website, try to forecast the weather tomorrow – (temperature, precipitation, general conditions.) See what the “news forecasters” say. Check to see how you did. What would you do different the next time you try to forecast the weather?

Topic 2: How do satellites gather satellite information? How many weather satellite systems are on the NOAA website? Where is the closest NOAA weather station in your area?

Topic 3: What is a Merchant Marine? Where do Merchant Marines work?

Mission: Hydrographic Survey Geographical Area: Alaskan Coastline, the Inside Passage Date: Wednesday, September 21, 2011

Weather Data From The Bridge

Science and Technology Log

Mission: Hydrographic Survey
Geographical Area: Alaskan Coastline, the Inside Passage
Date: Wednesday, September 21, 2011