NOAA Teacher at Sea
Onboard NOAA Ship Rainier
July 16 – August 1, 2007
Mission: Hydrographic Survey
Geographic Region: Alaska
Date: July 26, 2007
Weather Data from the bridge
Visibility: 10 Nautical Miles
Wind directions: 325 degrees
Wind Speed: 10 Knots
Sea Wave Height: 1-2 feet
Seawater Temperature 13.9 degrees Celsius
Sea level Pressure: 10009.2 millibars
Cloud cover: Partly Cloudy
Science and Technology log
I wondered how the survey technicians know they are in the right place and they continue to be in the right place while the data is collected. The short answer is satellites or GPS. While this was explained to me, here is the official info regarding known location, as explained by NOAA’s Earth Systems Research Laboratory:
“Global Positioning System. GPS was developed by the U.S. Department of Defense to tell us basically three things: where we are, how to get where we want to be, and what time it is right now. This is commonly referred to as “PNT” which stands for positioning, navigation, and timing. GPS is a “dual-use” system in that it has both military and civilian applications. To facilitate the development of civilian applications, the U.S. Government makes the radio signals broadcast by the GPS satellites available to every user free of fees. As a result of this policy, a multi-billion dollar industry has developed to exploit the benefits of GPS for civilian applications. For example, a commercial GPS navigation system in your car tells you where you are on an electronic map that is constantly updated as you move. Computer software in the navigation system tells you the best route to take to get to your destination. Wireless communications between your navigation system and a traffic management system tell you the best route to take to avoid delays or hazards.”
To find out more about the GPS please go to the following link where I found the above paragraph: http://www.esrl.noaa.gov/news/2007/gps/
The launches can only collect data when there are a minimum of five satellites receiving and transmitting in orbit above the area that is being surveyed. The use of five satellites lessens the chance that the information may be skewed by a distortion from one of the satellites.
The survey launch collects data from the sonar device that is located in the bottom of the ship; the computers assemble the feedback on board the launch and continually retransmit that data via satellite back to the RAINIER and it is processed during the evening hours. The work runs right through the night, with technicians working to ensure the sonic images are transferred into a coherent chart.
The areas today have not been surveyed in the past eighty years. Obviously the technology has changed markedly since the last survey. To view more about historical surveys click the following NOAA link.
I finally had a chance to pilot the launch and of course it looked far easier to do than when I tried it myself. It seemed like a simple task, to keep the nose, or bow, of the boat on the specific course and while I understood it well enough my attempts were often less than perfect. The sea was clam with negligible wave height. The wind was perceivable but not a large influence. The current was strong but steady and predictable. The route was clearly indicated on the screen in front of me and yet I could not hold the course steady enough (at least not well enough to collect valid data). Perhaps I was being too hard on myself: most annoying was the bow of the boat would head in the direction that I wanted it to but the stern of the boat (reacting to the force of the currents) dragged in a way that caused me to simultaneously both over and under compensate for the action. That coupled with the fact that I had no island or land point of reference made this experience a challenge. With the help of Mr. Foye, I was given some expert coaching that allowed me to get into a zone. I was in a pattern of both over and under steering and each correction brought me further away from where I wished to be. I learned that you develop a feel for this sort of thing and while I tried my best, I knew it would take many days of practice before I developed competency navigating this boat.
As the launch approaches the RAINIER, the person near the bow of the launch has a line ready to throw to the crew on board the ship (same in the stern). The crew on the larger ship needs to hold the launch so it doesn’t bang into the RAINIER. RAINIER then lowers two cables to attach to the launch (one on the bow and one on the stern). The cables are hooked onto large shackles and when all is secured the signal is given to the operator to hoist up the launch. There is only one person signaling to the operator on the ship. If there is ever a problem, naturally anyone can alert the crew of the problem but there is always only one person signaling to ensure safety of all.