NOAA Teacher at Sea
Aboard NOAA Ship Rainier
July 29, 2013-August 15, 2013
Mission: Hydrographic Survey
Geographical Area of the Cruise: Shumagin Islands, AK
Date: August 9-13, 2013
Weather Data from the Bridge:
GPS location: 54°49.910’N, 159°46.159’W
Sky condition: OVC
Visibility: 5 nm
Wind: 10 kt, 135 true
Water temperature: 7.2°C
Air temperature: 11.0°C
Science and Technology Log
At the beginning of my time aboard the Rainier I couldn’t believe it when one of the hydrographers told me that it takes almost two years for the data that we are collecting right now to go into print. After spending time with the scientists trying to understand the process, I have a better idea of why the data can take up to 24 months to appear on a chart. There are numerous things to take into account: variables that need to be controlled for, inclement weather that may restrict completing data collection, limited personnel to process the data, reports that need to be written to accompany the data, and so on. The point being is that it is not as simple as surveying the ocean floor and making a chart.
The tides are one important variable that hydrographers must control for when they are collecting data. Tides constantly cause the depths of the water to change, but it is important for the charts to show the shoalest (most shallow) depth possible for safe navigation.
It’s not practical to only conduct surveys during low tides, so the data must be corrected to take water depth to a universal constant. For most of the charts, NOAA uses Mean Lower Low Water as the control. To explain Mean Lower Low Water, I have to review a bit about the tides themselves. Most places, including Alaska, experience semidiurnal tides meaning that in one day, there are two high tides and two low tides. If you look at the two low tides in one day, one of the two will be lower than the other one. An average should be taken of the “lower low” water levels for 19 years. This is how long the earth, sun, and moon to go through their various orbital eccentricities. Typically, it is not reasonable to have a gauge installed for 19 years so by acquiring one 30 day cycle of tide data we are able to get approximately 90% of the solution and the remaining 10% is solved for using “primary stations” (ones which have a 19 year record) that are nearby. This calculated average of the lower low tides is called the Mean Lower Low Water and all data is corrected to this value.
Before the water depth can be corrected to Mean Lower Low Water, the tides must first be measured. The National Water Level Observation Network has stations all over the United States which give data on how to figure out local tide conditions. The closest one to use in the Shumagins is at Sand Point on Popof Island. In order to verify that the tides are being accurately predicted, the crew on the Rainier installs their own tidal gauge to verify the tidal data.
A tide gauge is installed on the sea floor near the coast line by divers. It must be fairly deep so that it is always covered by water. In order to verify that the tide gauge is working, a tide staff is installed nearby for the crew to take visual water level measurements every week for 3 hours in 6 minute increments. They use this manually collected data and compare it to the tide gauge to make sure that the gauge is functioning accurately and also to ensure that the gauge has not moved relative to the land after it has been installed.
It is a complicated process to install one of these tidal gauges, and they have to be calibrated to that Mean Lower Low Water. In order to assure that we have a reference point on land, benchmarks are put in near the tide gauge. These benchmarks should be able to be utilized for centuries by anyone who wished to come back to set-up a tide gauge.
Last Friday I was assigned to the skiff (small boat) as part of the crew of people who would go observe the tide staff and complete other necessary tasks at the tide gauge station on Bird Island. It was a 30 minute ride in the skiff from the ship, and when we got the island, the coxswain pulled the boat next to the rocks so we could quickly transfer ourselves and our gear onto the island. A total of five benchmarks had been put into the bedrock during the last visit to Bird Island, and it was our job to verify the location of each benchmark.
We took GPS locations, measured from benchmark to benchmark, and took pictures with detailed notes telling where each of the five was located. If something happened to the primary benchmark, there would be four back-ups that could be used to reference the location of the tide gauge. It was also the responsibility of our crew to do the 3 hour tide staff observations, but bad weather only allowed us to complete one hour of data collection before we were required to return to the ship.
It constantly impresses me how many variables these scientists need to control for in order to get accurate depths to place on the charts. I have only received a snapshot of the work that goes into one of these projects during my time aboard the Rainier. I have begun to see a problem when so many people of this generation expect instant results and instant gratification. From now on it will be important for me to show my students that the scientific process is slow and arduous, but the overall results are impressive when you learn to appreciate and understand the steps that it takes to get there.
Earlier this week I had the opportunity to visit the engine room as the ship was getting underway. Evan McDermott , a 1st Assistant Engineer on board, was kind enough to let me to follow him through the heart of the ship. As we walked and ducked under the various equipment, I began to realize just how naïve I am about how the ship is powered. As I began to observe and ask questions, I realized just how much time and effort it takes to get the ship in motion.
When I first went down to the engine room they had just turned the pumps on. These pumps are used to help turn the rudders. Each time the pumps are powered on, it is required that the engineers do a steering test. I went with Joshua Parker, a GVA (General Vessel Assistant) in the engineering department on board, as he showed me how to complete the steering test with the rudder.
While we were anchored, the engines were powered down and we were running the basic functions of the ship with two generators which stay on 24 hours a day while the ship is underway. When I came back to the engine room it was time to turn the engines on, and Evan walked me through how to do this. Really all I did was push two buttons that he showed me, but it was neat to hear the engines come to life.
While I was in the engine room, I remembered several of the questions my students had when the CO came to speak to my class last year. I seemed to remember a lot of students asking questions about the fuel that the Rainier uses. I decided to do some investigating by asking some of my own questions. It turns out that the ship is able to carry a total of 103,000 gallons of fuel at a time. On a typical 18 day leg, the ship will burn about 30,000 gallons of fuel. Evan pulled up a detailed Microsoft Excel sheet and showed me how they keep track of the fuel being used. He showed me that while underway the ship typically burns about 2,000 gallons each day, but if the ship is anchored it is more like 600 gallons.
Something else I learned while in the engine room was how this ship uses fuel as ballast. Normally on a ship, ballast is water that is taken in to help keep the ship balanced. The Rainier has 17 fuel tanks all around the ship, and one of the reasons for this is to give the ship stability.
For this reason, it is important that the fuel is burned in a certain order based on which tank it is in. Once the engineers decide that they need to use fuel from a certain tank, it is transferred into two settlers. This is where the water is allowed to settle out of the fuel before it is purified and transferred to the day tanks. These two-day tanks are where the two engines suck fuel from directly.
The last thing that grabbed my attention in the engine room was the process on how the sewage is filtered. I know it sounds gross, but it is such a simple chemical reaction that I feel compelled to share it! The machine that is responsible for this treatment uses salt water and DC current. The current is run through the water and breaks the salt (NaCl) into the ions Na+ and Cl–. The Cl– ions go on to reform with the OH– ions from the water forming sodium hypochlorite. This substance acts to kill the bacteria in the sewage. Chemistry at work!
Just another Day at the Office
Evan McDermott, 1st Assistant Engineer
After touring the engine room, I sat down with Evan to talk about his job and how he came to work for NOAA as a 1st Assistant Engineer. He told me that he graduated from Massachusetts Maritime Academy with a BS in Marine Engineering as well receiving his US Coast Guard license. I didn’t know what a Maritime Academy was until I came aboard the Rainier, so I asked him how he originally heard about this field. Evan told me that in high school he went through a unique program where he spent two days each week doing marine engineering outside of his school. A guidance counselor told him more about the benefits of marine engineering, and that’s when Evan decided to apply to Massachusetts Maritime Academy.
During our conversation, Evan told me that what he enjoys most about his job is the variety of hands-on work that he gets to be involved in, and he also enjoys the scenery here in Alaska. He is required to stand watches in the engine room for two 4-hour shifts while the ship is underway, and he also plays a supervisory role. The engineering department on the ship is mostly responsible for the maintenance and operations. I asked him to share the advice he would give to students hoping to get into this field of work, and he said that it is important to keep up on your math to become a marine engineer! Evan told me that the Maritime Academy was a tough four years of his life, but that his hard work has paid off as he has now secured this job with NOAA.
Evan appreciates the fishing that is available in Alaska, and when not on the ship he enjoys snowboarding.
Your Questions Answered!
A friend from my high school, Derek Cusimano, works with similar technology that is being utilized on the Rainier. I was excited to see the questions he had for me, and also to realize that I actually understood how to answer some of the more technical questions. First he asked about the program that is used to collect and process the data on board. It is my understanding that on the ship, Hypack is the navigation software that is used. The bridge sees this screen, and the hydrographers use it to draw the lines to show where the ship needs to be navigated in order to collect the data. Seafloor Information Systems (SIS) is the sonar software for the EM710. Finally, CARIS is the software that is used to process the data once it is collected.
Derek also asked me about what positioning the crews use for their surveys. The tidal gauges that I discussed in this post are used for vertical control, as the water moves up and down with the tides. The scientists also have to take into account horizontal control. They need to accurately be able to tell where their position is, because without that information the water depths that we are gathering with the sonar are useless.
Differential Global Positioning System (DGPS) is used from the Coast Guard station in Kodiak Alaska to gain accurate latitude and longitude. However, the Rainier crew also installs their own GPS base stations to correct the GPS positions acquired on the ship and launches during “post processing”. For this project, a GPS base station was installed on Bird Island near the tide gauge and data is down loaded via a VHF radio. These stations listen to all GPS signals and correct the locations for each satellite down to the decimeter. This allows the Rainier to correct their GPS positions to have an accuracy of just a few centimeters.
The next question comes from my 2-year old nephew Ollie Burgeson. He wanted to know what I was eating on the ship. My answer to him is a little bit of everything! I can’t say that I’ve had the same meal twice while out at sea. Meals are at 0700, 1130, and 1700, and each day a menu is posted that tells what will be available for breakfast, lunch, and dinner. The stewards also provide a stocked ice cream freezer and other snacks 24 hours a day. Many know that I eat mostly vegetarian food, and each meal there is always a vegetarian option which several crew members and I enjoy. While out on the launches, the coolers are packed full of food for the crew of each boat. Sandwiches, fresh fruit, chips, and dessert are all included on the launches.
Did You Know…
On Sunday I saw at least a dozen whales while I was looking out over the waters of the Shumagins. The ship was anchored while the launches were out gathering data. It was such a clear day that I decided to spend time on the bridge whale watching. It didn’t take long before I saw several breach in the distance. I was told by some of the crew that I was observing humpback whales, Megaptera novaeangliae. I didn’t know much about them, so I decided to do a bit of research. Here are some of the interesting things I learned about humpback whales:
- Humpback whales can be found in all major oceans from the equator to sub-polar latitudes
- The humpback whale’s lifespan is about 50 years
- They eat mostly krill, plankton, and small fish
- Humpback whales can consume up to 3,000 pounds of food per day
- Females are typically longer than males, and they can reach up to 60 feet in length
- Newborns weight about 2,000 pounds and adults can grow to be between 50-80,000 pounds