Tag: coxswain

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Jill Stephens, June 18, 2009

NOAA Teacher at Sea
Jill Stephens
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 18, 2009

Weather Data from the Bridge 
Position 55° 10.089’N 161° 52.801’W
Broken cloud cover
Wind variable and light
Pressure 995.9
Temperature: Sea; 6.1°C;  Dry Bulb; 8.3°C; Wet Bulb; 7.8°C

The Reson monitor displays the sonar return captured by the receiver on the bottom of the boat.
The Reson monitor displays the sonar return captured by the receiver on the bottom of the boat.

Science and Technology Log 

The launch leaves the ship every day to go to spots within the survey area to collect data regarding the bottom for depth, possible anchorage sites and potential navigational hazards.  Our boat was responsible for covering the long area referred to as the fairway, which is necessary in this uncharted area so that the launches can transit to and from the working areas safely, and move on to another area upon completion.

The chart of the area is “painted” with color depicting the depth of the area based upon the return form the sonar. The goal is to “paint” your assigned area. The numbers in the lower right of the screen indicate the depth in meters.
The chart of the area is “painted” with color depicting the depth of the area based upon the return form the sonar. The goal is to “paint” your assigned area. The numbers in the lower right of the screen indicate the depth in meters.

The inside of the cabin of the launch reminds me of Star Wars. There are pieces of electronic equipment everywhere!  One of the survey team members sits in the command center to monitor and control the Reson collection and additional software that displays a 3-D image of the sea floor surface. As the coxswain pilots the boat over the surface of the water, low frequency sonar is emitted from the transducers.  The sonar hits the sea floor and is then bounced back to a receiver on the underside of the boat.  The pings are recorded by the equipment and stored in the computer. 

The CTD is attached to a cable operated by a winch. The CTD acclimates to the water surface temperature before being lowered steadily to the bottom. The equipment is raised to the surface using the winch and then brought aboard. The CTD is connected to the computer for data retrieval.
The CTD is attached to a cable operated by a winch. The CTD acclimates to the water surface temperature before being lowered steadily to the bottom. The equipment is raised to the surface using the winch and then brought aboard. The CTD is connected to the computer for data retrieval.

There are factors that affect the accuracy and quality of the information.  Boat speed, conductivity of the water, pitch and roll, yaw, and tides must be accounted for in order obtain usable data. There is equipment on board that collects the pitch, roll, yaw, and geographic position information to correct merge with the data to make corrections.  The CTD apparatus is placed into the water while the boat is stopped. The cast of the CTD will collect salinity, temperature, and pressure information at depths from the surface to the bottom. This information is also sent to the computer to provide a more accurate reading of the sonar data received by the Reson system.  Casts of the CTD must be made a minimum of every four hours to account for any changes between points in the survey area.

Personal Log 

Here I am manning the computers onboard the launch used to collect sonar depth and bottom information in the Pavlof Islands, Alaska.
Here I am manning the computers onboard the launch used to collect sonar depth and bottom information in the Pavlof Islands, Alaska.

Shawn, Todd, and Dennis were on my launch today. Once the equipment was powered up and the software programs selected, I was able to sit at command center and control collection and storage of data. The raw data is merged with the corrective information and submitted to Caris, another software program that also creates models of the findings. We were using a laptop to merge the data and begin field processing of the data. I was able to assist with this process too.

Two whales surfaced near the survey launch early in the morning near Bluff Point in the Pavlof Islands.
Two whales surfaced near the survey launch early in the morning near Bluff Point in the Pavlof Islands.

Animal Sightings 

This morning was a great day to see whales!! We spotted 5 blows!  We were then able to see the whales breach the surface at a distance.  Three of the whales moved closer to us. There were two adults and a juvenile. The juvenile was very playful and kept poking his head above the surface.  The two adults came closer to the launch and we were able to get some great shots of their bodies!! On the way back to the ship, we saw four more blows. Total sightings of whales: 9 Puffins as always are out there. They are very strange, somewhat silly birds…. 

New Vocabulary Gain: how hard an object is listening to the sound emitted by the sonar Sound Speed: speed at which sound is able to travel (This will vary in water depending upon the factors like salinity and temperature.)

Absorption: refers to how much of the sound is absorbed by the medium and varies with the medium’s composition and other factors including temperature. 

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Jill Stephens, June 17, 2009

NOAA Teacher at Sea
Jill Stephens
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 17, 2009

Weather Data from the Bridge 
Position: Anchored, Bluff Point, AK; 53° 10.087’ N, 161° 52.801’ W
Visibility 10 nautical miles
Wind 060 at 6 knots
Temperature 8.3° C dry bulb, 7.8° C wet bulb
Barometric pressure 995.7
Sea Temperature 5.6° C

Science and Technology Log 

This morning everyone was abuzz with excitement because today we were to send out the launches and begin to survey the area in the Pavlof Islands that has not yet been charted! The data that we will be collecting during this survey, such as depths and hazards to navigation, will eventually end up on nautical charts.

Here I am driving the launch. It is essential to hold a steady course while collecting data for the surveys and tests.
Here I am driving the launch. It is essential to hold a steady course while collecting data for the surveys and tests.

Deploying the launches is a fascinating thing to watch. The davits on our ship rely upon gravity, (Newton’s Laws in action…).  The boats are attached with cables and the weight of the launch is used to lower it to the water. As the cable is slowly released, deckhands man lines to assist in guiding the launches slowly toward the water. The crew and their gear are loaded from one of the lower decks and then the launch is lowered the rest of the way to the cold Alaskan water.  Once the launch is in the water, the cables are released from the launch.

The launch that I went out on was running patch tests and collecting Reson data.  The patch tests are necessary to calibrate the multibeam sonar and measure any physical offsets that may induce errors into the acquired data. In order to accomplish this test, we collected data with the sonar by running lines over an area that was surveyed last year.  The sonar that is used to collect information about the depth and underwater objects can be either high or low frequency.  It was important for our boat to test both frequencies.  The frequency used depends upon factors such as the depth of the water.

Personal Log 

Having been on board ship for two days already, I am getting the feel for where everything is located and how meals work.  Now, I have also been introduced to the routine of launching and conducting surveys. Our coxswain allowed me to pilot the boat for one of the runs during our testing. My time on boats at home and on sailing excursions is paying off.

When I visited the bridge to write down the weather information, the officer on bridge watch, Ensign Andvick, was preparing to collect the hourly weather information.  I assisted in the collection of the required data and was excited to be able to learn where the weather instruments are located on the bridge.  I enjoy data collection, so I will time my visits to coincide with the hourly check of the weather, which becomes a part of the ship’s log.  While on the bridge, I also learned that there is some difficulty communicating by radio from the ship to launches in this area. The islands in this area are very high and mountainous, but in similar areas this difficulty has not been noticed. One possibility for the communications issue is that the mountains here have a higher concentration of iron that interferes with the signal.  (Sounds like an idea for a science fair project….). The launches have other methods to communicate with the ship and other launches such as satellite phones.

I had the opportunity to spend time in the plot room with fellow teacher at sea, Mary Patterson while the night processors were working on the data collected during the day.  We continue to meet and work with interesting and fabulous people.

New Vocabulary 

Coxswain: boat driver/operator — The coxswain is responsible for the operation of the boat and the safety of all occupants and equipment.