Tag: multibeam sonar

Posted on

Miriam Sutton, June 17, 2005

NOAA Teacher at Sea
Miriam Sutton
Onboard NOAA Ship Nancy Foster
June 17 – 22, 2005

Mission: Stellwagen Bank National Marine Sanctuary Survey
Geographical Area: New England
Date: June 17, 2005

Weather Data from the Bridge
Visibility: 10 nautical miles (nm)
Wind direction: 200°
Wind speed: 13kts
Sea wave height: 2-3′
Swell wave height: 1′
Sea water temperature: 15.6°C
Sea level pressure: 1005mb
Cloud cover: Partly cloudy

Science and Technology Log

I am onboard NOAA’s R/V NANCY FOSTER and am heading toward the Stellwagen Bank National Marine Sanctuary. This sanctuary is located off the east coast of New England between Cape Ann and Cape Cod, Massachusetts. I will be exploring this area with a group of NOAA and National Marine Sanctuary (NMS) scientists as they search for various anomalies located along the seafloor. “Anomaly” is the term used to describe artifacts or other materials that do not follow the normal pattern of the seafloor topography or geology. My Teacher at Sea assignment with the NANCY FOSTER will allow me to observe and assist the scientists using remote sensing equipment to detect these anomalies.

Today, we traveled from Woods Hole, MA through the Cape Cod Canal on our way to Stellwagen Bank where we began our search for seafloor anomalies. Transect lines are coordinates determined by the Chief Scientists, Matthew Lawrence, and are provided to the ship’s captain for steering our course to the correct location. Two different remote sensing instruments were used in our first set of transect lines: the side scan sonar uses sound waves to record images along the seafloor and the magnetometer detects electromagnetic fields that might be emitted by the anomalies. As the plotted site is reached, the ship’s engines are slowed and the “towfishes” are lowered off the stern of the boat using a cable and winch system. (See photos A, B, and C) The goal of our first search was to try and locate a NOAA data collector buoy and anchoring wheel that failed to surface when NOAA sent a radio signal for the buoy to release from its mooring. The buoy was used to collect data on cod fish that were tagged to determine their general range within the sanctuary. The data would let scientists know if these cod used the sanctuary as a habitat or if the fish were just passing through. After several passes, or transect lines, we were unable to locate any significant anomalies that might have indicated the location of the wheeled mooring and the buoy. The remote sensing equipment was brought to the surface and stored away for the night. Our ship is now heading closer toward shore to anchor overnight.

Posted on

Christy Garvin, June 8, 2005

NOAA Teacher at Sea
Christy Garvin
Onboard NOAA Ship Rainier
June 1 – 8, 2005

Mission: Hydrographic Survey
Geographical Area: Aleutian Islands, AK
Date: June 8, 2005

Weather from the Bridge

Latitude:56 deg 44 min N
Longitude: 135 deg 43 min W
Visibility:10 nautical miles
Wind Direction: 160 deg
Wind Speed:14 kts
Sea Wave Height1-2 ft
Swell Wave Height:4-5ft
Sea Water Temperature: 53deg F
Sea Level Pressure:1011.5 mb

Humpback whales
Humpback whales

Science and Technology Log 

Since we were doing ship’s hydro again today, I decided to take the opportunity to interview some of the NOAA junior officers to learn more about what their job entails and what long-term life at sea is like. The two officers on watch were Briana Welton and Jay Lomnicky.

Briana attended Smith College in western Massachusetts; she majored in math, but learned about NOAA through the science department at Smith.  While in college, she interned for NOAA and enjoyed the experience.  She graduated from college and found that her job working in a cubicle was boring and tedious; looking for adventure and a different style of life, she applied with NOAA and became a junior officer.  She has been onboard the RAINIER for almost two years, and while onboard she has worked in the survey department, been in charge of tide information for the ship, and stood anchor watch on the bridge.  Briana will be leaving the ship in December for her three-year shore duty. Her shore assignment will be with a Navigation Response team that will do surveys in the mid-Atlantic region.

Breaching
Breaching

Jay learned of NOAA from a friend who was working for a fish and wildlife agency in Florida. He has a degree in biology and has been on the ship for two and a half years.  His collateral duty is dive master, and he is in charge of all dive operations on the ship.  There are eight certified divers onboard who set up tide gauges, complete hull inspections, and use lift bags to recover items from the ocean floor.  It is Jay’s job to plan all dives, ensure that the nearest decompression chamber is operational, check to make sure the equipment is working properly, and assess diver’s skills.  When Jay leaves the RAINIER in about a month for his shore duty, he will be working with side scan sonar looking for fish habitats. Jay really enjoys ship life; he likes steering the ship, the adrenaline rush of rough weather, and managing and coordinating the activities of those on board.

Both Jay and Briana had advice for those seeking a career with NOAA.  First, they encouraged a math or science degree and suggested that basic seamanship (tying knots, navigation, life at sea) and knowledge of the ocean would be helpful.  They also suggested that individuals should understand that working on a ship is not a job, it is a lifestyle.  Sometimes it is difficult to have relationships or hobbies, and many conveniences like radio, television, and private quarters are often not available.

Personal Log 

While the ship was doing hydro today, I saw two humpback whales breaching.  They would bring their large pectoral fins high in the air and slap them down on the water, then they would do a tail lob, which is when they bring the fluke up in the air and flip it around. It was definitely an amazing sight.

Posted on

Christy Garvin, June 7, 2005

NOAA Teacher at Sea
Christy Garvin
Onboard NOAA Ship Rainier
June 1 – 8, 2005

Mission: Hydrographic Survey
Geographical Area: Aleutian Islands, AK
Date: June 7, 2005

Weather from the Bridge

Latitude:56 deg 59 min N
Longitude: 135 deg 17 min W
Visibility: 11 nautical miles
Wind Direction: 290 deg
Wind Speed: 10 kts
Sea Wave Height: 0-1 ft
Sea Water Temperature: 50deg F
Sea Level Pressure: 1011.7 mb

Science and Technology Log 

Although we have been parked in protected Aleutkina Bay for most of the leg, yesterday afternoon we pulled anchor and the ship was underway.  Because of weather conditions, it was determined that the ship would run hydro in deep water, while the launches continued protected shoreline work.

The ship is equipped with a Seabeam 1050 MKII; it is a dual frequency echosounder with 50KHz and 180KHz operating frequency. When operating at the 180 KHz frequency a maximum depth of 620 meters can be surveyed.  This depth can be increased by switching to the 50 KHz frequency, which can reach depths of 3,100 meters.  The Seabeam 1050 has a wide horizontal scan area that is covered by 126 adjacent beams and a 150-degree swath width; it has high resolution due to the narrow beams it uses.

While the ship is doing hydro, the crew transitions into 24-7 watches.  The ship runs survey lines all night, so people are needed to steer the ship, serve as lookouts, and run the survey equipment.  The watches are four hours each, and crewmembers work two watches a day. The three shifts are 12:00-4:00, 4:00-8:00, and 8:00-12:00; people are sleeping at different times, so everyone makes an effort to be quiet during the day.

One of the highlights of today was an in-depth tour of the ship by the CO, John Humphrey.  I was able to see the engine room with the two main engines, the after steerage (where the rudder and emergency steering are located), and the evaporator unit that processes salt water into potable fresh water.  We also went into the large refrigerators and freezers that hold the ship’s stores and climbed down into the bowels of the ship to see the fire prevention carbon dioxide system.

Personal Log 

It is interesting trying to sleep while the ship is underway. Although the seas aren’t very rough, the ship still moves quite a bit.  I haven’t been seasick (I’m very thankful for that), but I rolled all over my bunk last night.  It felt like I was trying to hold myself in the bed as I slept.

Posted on

Christy Garvin, June 6, 2005

NOAA Teacher at Sea
Christy Garvin
Onboard NOAA Ship Rainier
June 1 – 8, 2005

Mission: Hydrographic Survey
Geographical Area: Aleutian Islands, AK
Date: June 6, 2005

Weather from the Bridge

Latitude:56 deg 59 min N
Longitude: 135 deg 17 min W
Visibility: 11 nautical miles
Wind Direction: 290 deg
Wind Speed: 10 kts
Sea Wave Height: 0-1 ft
Swell Wave Height: 0 ft (we are in a protected bay)
Sea Water Temperature: 50deg F
Sea Level Pressure: 1011.7 mb

Science and Technology Log 

My assignment today was to work on launch RA-2 taking bottom samples and running “holiday lines.”  A holiday line is an area where previously drawn survey lines did not provide 100% coverage of the ocean floor, in other words, a small hole in the data.  Our launch was working on sheet R in Leesoffskaia Bay and Aleutkina Bay.  These bays are near Emengton, Long, and Baranoff Islands. Taking bottom samples is a very simple but important task.  The information gathered allows boaters to know where good anchorage locations are and fishermen to figure out probable fish habitats and increase their yield.

In order to take a bottom sample, survey techs pre-select specific locations to be sampled.  Once in the launch, the target is selected on the computer, and the coxswain drives to that location. The survey tech then takes a depth sounding to record the exact location and depth where the bottom sample is being taken.  A device called a clam is attached to a rope and thrown overboard; when the clam hits the bottom a spring releases causing the “mouth” to shut and capture sediments on the ocean floor.  The clam is then pulled to the surface and opened so that the survey tech can record the type of sediment or rock present. Later, this data is added to nautical charts as an aid to boaters.

Personal Log 

Last night the crew of the RAINIER had a nice beach party.  A nearby island was chosen, and crewmembers were ferried over to stretch their legs, hike around the island, and enjoy a bonfire. It was a nice surprise to end the weekend.

Posted on

Christy Garvin, June 5, 2005

NOAA Teacher at Sea
Christy Garvin
Onboard NOAA Ship Rainier
June 1 – 8, 2005

Mission: Hydrographic Survey
Geographical Area: Aleutian Islands, AK
Date: June 5, 2005

Weather from the Bridge

Latitude: 56 deg 59 min N
Longitude: 135 deg 17 min W
Visibility:12 nautical miles
Wind Direction: 275 deg
Wind Speed: 10 kts
Sea Wave Height: 1-2 ft
Swell Wave Height: 0 ft
Sea Water Temperature: 54deg F
Sea Level Pressure: 1016 mb

Science and Technology Log 

Instead of running survey lines on a launch today, I was assigned to the plot and holograph rooms to learn what happens to the survey data when launches return to the RAINIER each evening.  Depending on the weather conditions, launches return to the ship each afternoon between 1630 (4:30 p.m.) and 1730 (5:30) p.m. Once they have been raised out of the water with the gravity falls davits, the survey techs plug the launch’s computer system into the main system on RAINIER.  At this time, the data is pushed (or downloaded) to the ship’s main network.

Two different software programs are used in the process; the launches use a program called ISIS to run the sonar, while the GPS mapping software onboard is Caris.  Therefore, the data collected on the launches must be converted into a form that can be read by Caris. During the conversion process, data corrections are made based on predicted tides, the sound velocity curve created by the CTD, filtering out the outer, less reliable sonar beams, and total propagated error (a statistical compilation of error based on the specific error inherent within each system).

Once the data has been converted, the survey techs go through each line individually and clean the line by removing random sonar reflections.  These reflections can be due to kelp beds, schools of fish, the boat’s motor, or internal timing of the sonar.  Once all of the lines on a sheet are complete, the sheet is sent to PHB (Pacific Hydro Branch) where the data is used to make nautical charts that are used by the fishing and cruise industries, as well as by any others who navigate these waters.

Personal Log 

The CO of the RAINIER took me out on a skiff for a couple of hours today to see some of the bays near Sitka. We saw a harbor seal, a sea otter, and lots of bald eagles; the mountains seem to rise right out of the water, and they are absolutely breathtaking with their snow-capped tips.