bottom sampling – Page 3 – NOAA Teacher at Sea Blog

June 9, 2009April 5, 2021

Susan Smith, June 9, 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 9, 2009

Weather Data from the Bridge
Temperature: Dry Bulb: 12.2° (54°F); Wet Bulb: 11.1° (52°F)
Cloud Cover: Overcast 8/8
Visibility: 10 Nautical Miles
Wind direction: 315, 08 kts.
Sea Wave Height: 0-1
Sea Water Temperature: 12.8°C (55°F)

Science and Technology Log

Question: What might an empty bottom sampler indicate? There might be a hard bottom, so it is not a good place to try to anchor.

Today we took bottom samples in ten locations. The objective of bottom sampling is to update historical data and look for good anchor locations. This chart has five locations where we took bottom samples. They are shown where the stars are. The red symbol depicts our launch driving from one point to the next.

There are many houses, and what appeared to be summer hotels, in this area, so they must have accurately charted information. When we performed our bottom sampling, the bottom sampler was affixed to a rope which we dropped over the side of the launch. Some times a weight is put on the rope so it will hit bottom with more force. After we tried three times and the claw was not closed we put a weight on and it closed from then on.When the sampler hit the bottom the claw of the sampler shut, trapping whatever was in that locale. We then brought the rope back up and opened the sampler to observe its contents.

Susan sending the sampler down with Shawn’s help

We found the following materials:

43 feet deep: nothing in three tries- must be a hard bottom
50 feet deep: very densely packed green, sticky mud
47 feet deep: same as number 4
168 feet deep: big rocks only
130 feet deep: fine, green, sticky mud
47 feet deep: piece of black plastic (like a coffee stirrer), very fine black silt
37.5 feet deep: black sand with kelp
2. 168 feet deep: black, sticky mud
1. 100 feet deep: grey sand, three rocks of varying sizes
small rocks Of these samples, green, sticky mud indicated the best locations for anchoring.

Personal Log

We departed Trocadero Bay in the late morning. As we headed toward Glacier Bay for our tour on Wednesday we had our abandon ship and fire drills. When we did not complete the series of three drills (man overboard drill is the third one), I asked what the chances were of having this third drill. As it was explained to me we generally have the man overboard drill if we are ahead of our dead reckoning. When asked what that is I was told, “If we are where we are supposed to be when we are supposed to be there”. Here’s the dictionary definition of dead reckoning- Dead Reckoning: 1. calculation of one’s position on the basis of distance run on various headings since the last precisely observed position, with as accurate allowance as possible being made for wind, currents, compass errors, etc.; 2.one’s position as so calculated.

On the chart times of arrival are written in pencil so adjustments can be made.

This was important because were to pick up a National Park Service guide for our tour into Glacier Bay and we could not be early. A man overboard drill takes a great deal of time, because the ship must go back to its position when someone fell overboard. This entails making a huge circle with a ship that is 231 feet long, 42 feet wide, and has a displacement of 1,800 tons. As you can imagine just the turning around alone takes a considerable amount of time.

For more information on the NOAA Ship Rainier (S-221) go here.

June 4, 2009April 5, 2021

Susan Smith, June 4, 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 4, 2009

Weather Data from the Bridge
Visibility: 10 nautical miles
Wind: light
Temperature 11.1 C (52 F)
Cloud Cover: FEW 1/8-2/8

A nautical chart indicating underwater cables

Science and Technology Log: Bottom Sampling

This morning I spent time in the Plot Room, and on the Fantail, involved in bottom sampling. The Plot Room has nine work stations with at least two screens per technician. The airplane symbol is the location of the Rainier and the colored dots show locations of bottom sampling areas. One purpose bottom sampling serves is to determine areas suitable for anchoring.

The chart to the right shows there is an underwater cable area (pink dotted lines) from which we cannot take samples, because it could accidently get damaged, thus rendering residents without power. The numbers shown on these When the ship takes bottom samples, from the Fantail, it uses a spring loaded clamp shell device. It is attached to an A frame and uses a winch to lower it into the sea by cable. The operator calls out the depth, using a cable counter, as it is lowered into the water and when it raised. This enables the plot room to know when a sample is coming and it verifies the information received remains accurate. The numbers on these charts indicate water depth in fathoms (1 fathom=6 ft.). As you can see there are drastic dropoffs in some locations.

Identifying the samples: small coarse pebbles

If the cable is not straight down, the ship must move around it, avoiding the screws (propellers) at all costs. When the clamp hits bottom it scoops up the debris under it immediately and is brought back to the surface. When the sample arrives at the top it is shaken to release a majority of the water. Then it must be dismantled to see the solid matter inside. This is a two person job, as it is heavy and impossible to control for just one person. One holds the spring loaded clamp shell, the other takes off the sample section by pulling on either side of the device.

Because safety is always an issue the clamp must be kept from swinging once the collection unit is removed. The items found in the sampler are placed on the chart (shown to the right) to make sure identification is accurate. The chart is divided into sand, gravel, and pebbles. Each type of rock found is divided further into fine, medium, and coarse. This information is relayed to the plot room where someone labels the survey chart in the appropriate location. In the first four samples green, sticky mud was identified near the coastline of Ladrones Island, Madre de Dios Island, and on the southwestern arm of the Prince of Wales Island. These were deep areas where people are not likely to anchor their boats. In the sixth sample we were in fairly shallow water and sampled gritty sand and small pebbles.

This sample was full of sand and some pebbles.

Sometimes the water arrives only with living things in the sampler. Samples eight through ten provided us with living things. Shells with little creatures inside were found in one sampling, and in another the only item was a black sea star. Finally after three such samples in the same location we moved on to the next location. This is a somewhat tedious process when the samples do not provide a great deal of useful data. However, that in itself gives sufficient information as to what is NOT in a location. Now imagine being charged with this assignment is an area where surveys have either never been done, or it has been decades since the previous survey. Remarkably the survey charts are fairly accurate, even from when lead weights and ropes were used to survey. NOAA certainly has a daunting task when it comes to surveying Alaska.

Personal Log

This sample had only a little black sea star!

Yesterday, and today, allowed me the opportunity to see the technical aspects of the Rainier’s mission. Small sections of the oceans and bays are meticulously mapped and charted for use by recreational boaters, the fishing industry, large shipping companies, and the military. Without the information gleaned by the people and ships of the NOAA Corps our waters would continue to go uncharted, perhaps unused, and remain hazardous to all. I am amazed at the patience needed for this work, but it is well worth their efforts to provide the necessary tools to keep our waterways safe for everyone.

I was discussing interesting things I noticed on the Rainier with several of the officers. Did you know there are two flags we fly on the NOAA ships? There is the Jack, a flag with the 50 stars and blue field, and the Stars and Stripes, our nation’s flag. When it is flown on a ship it is called an Ensign. The Jack is flown on the Jackstaff (origin 1865-1895) located on the ship’s bow. The Ensign is flown on the fantail while in port or anchored at sea. I suppose I have now become a student of vexillology, the scholarly study of flags.

July 14, 2005March 18, 2021

Debbie Stringham, July 14, 2005

NOAA Teacher at Sea
Debbie Stringham
Onboard NOAA Ship Fairweather
July 5 – 15, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: July 14, 2005

NOAA Ship FAIRWEATHER docked at US Coast Guard Station, Kodiak, AK.

Weather Data

Location: U.S. Coast Guard Dock, Kodiak, AK
Latitude: 57 48.6′ N
Longitude: 152 21.9′ W
Visibility: 10 nm
Sky Description: partly cloudy

Science and Technology Log

The ship has reached Kodiak, AK and has docked at the U.S. Coast Guard Station. Preparations are already underway for an inspection and the departure of crew members and arrival of returning or new crew members. The next leg will focus on fisheries research so preparations of the winches for nets is underway.

I’m a little wistful in returning to shore. I’ve grown accustomed to the rocking of the ship and have thoroughly enjoyed my entire experience aboard the FAIRWEATHER. I’m amazed at the autonomy of the ship and the crew aboard. I’m walking away with valuable and useful information that can be applied in laboratory experiments in the classroom and can hardly wait to implement them.

Tonight, I spend my last night aboard the ship and tomorrow morning depart for a day ashore Kodiak and then a long flight home. What an amazing experience this has been!

Answer from Previous Day

Believe it or not, the Indonesian tsunami and Alaska 1964 earthquake are important to hydrographic survey. Plates shifting near Indonesia created the large tsunami that traveled so far and decimated so many villages. The 1964 earthquake, also caused by shifting plates, creating likewise devastating effects. This impacts hydrographic survey, because the navigation charts printed before 1964 would not show the rise in sea floor of over 30 feet that occurred because of the shifting plates!

July 13, 2005March 18, 2021

Debbie Stringham, July 13, 2005

NOAA Teacher at Sea
Debbie Stringham
Onboard NOAA Ship Fairweather
July 5 – 15, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: July 13, 2005

Stringham photographing tsunami buoy recovery.

Weather Data

Location: in transit
Latitude: 52 44.1’N
Longitude: 156 45.3’W
Visibility: 10 nm
True Wind Speed: 10 kts.
True Wind Direction: 270
Sea Wave Height: none
Swell Wave Height: 6 ft.
Swell Wave Direction: 220
Sea Water Temperature: 11.0 C
Sea Level Pressure: 1008.0
Sky Description: partly cloudy
Dry Bulb Temperature: 14.0 C
Wet Bulb Temperature: 12.5 C

Science and Technology Log

Last night, the ship received word that a tsunami buoy had gotten loose and needed to be retrieved in waters to the south. So, heading to the farthest waters south that the FAIRWEATHER has seen since March, the ship made its way to the last known location of the buoy. I stood watch on the bridge from 0400 until 0800 and no sight of the buoy had been taken on RADAR or by person. At about 0830, the buoy was spotted and operations to retrieve it were commenced. A smaller vessel with four crew members was launched to aid in the retrieval and the A- frame on the fantail was rigged to pull the large instrument aboard. By 0930 the buoy was captured and hoisted onto deck and by 1030 it was securely fastened to the fantail. The issue of pulling aboard several thousand meters of the buoy’s rope took several more hours after that. Whew!

The December 26, 2004 Indonesia tsunami “traveled at 700 kilometers per hour to rear up like a hydra onto shores, sweeping away some 225,000 lives and millions of livelihoods across 12 nations,” Madhusree Mukerjee reported in the March 2005 issue of Scientific American. That historic tsumani event raised a lot of concern regarding the early warning systems that are in place for tsunami events. Unlike the Indian Ocean, the Pacific Ocean is known to have a well established warning system in place, but efforts are being taken to ensure that we know as much as possible about possible tsunamis in the Pacific Ocean. Tsunami buoys are located extensively along the major coastlines of countries neighboring the Pacific Ocean and the data collected from those buoys is carefully analyzed and recorded.

Ships similar to the FAIRWEATHER, in the NOAA fleet, usually perform routine maintenance and retrieval of buoys. The FAIRWEATHER has been looked at for this purpose, but never actually engaged in the process. This is the first time the FAIRWEATHER has taken part in tsunami buoy retrieval.

Question of the Day

What do the 2005 Indonesian tsunami, the Alaska 1964 earthquake, and hydrographic survey have in common?

Answer from Previous Day

The best types of sea floor to anchor a ship are mud/clay or sandy, mud combinations. Firm sand is okay, but loose sand, soft mud, rocks, and grassy/kelp areas should be avoided.

July 12, 2005March 18, 2021

Debbie Stringham, July 12, 2005

NOAA Teacher at Sea
Debbie Stringham
Onboard NOAA Ship Fairweather
July 5 – 15, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: July 12, 2005

Stringham on shore, Eagle Harbor, Shumagin

Weather Data

Location: Eagle Harbour, Shumagin Islands, AK
Latitude: 55 06.8’ N
Longitude: 160 06.9’ W
Visibility: 10 nm.
True Wind Speed: 16 kts.
True Wind Direction: 340
Sea Wave Height: 1 ft.
Swell Wave Height: none
Swell Wave Direction: none
Sea Water Temperature: 12.0 C
Sea Level Pressure: 1011.5 mb
Sky Description: Partly Cloudy
Dry Bulb Temperature: 15.5 C
Wet Bulb Temperature: 12.5 C

Science and Technology Log

View from vessel during bottom sampling operations.

Today, is a quiet day aboard the FAIRWEATHER. There are no vessel launches to join, but it is a good opportunity for me to work on lesson plan ideas. I’ve been most interested in the bottom sampling operations and why it is important to understand the nature of the sea floor for anchorage. I found a very helpful seaman text that should provide good direction for a lesson plan.

Earlier in the leg, a crew member and survey tech exchanged with a member of a contractor for NOAA that acquisitions hydrographic data using airplanes. The airplanes essentially have two beams, one that hits the top of the water and one that penetrates to the sea floor. The data is then compared and the difference between them equals the water depth. The survey tech said that there are some benefits and limitations to the use of airplanes.

Benefits are that it can collect data much more quickly than our ship. Our ship travels at ten knots, but the airplane can fly over a hundred knots and cover many more miles. The airplane can also collect data in shallow water and pinpoint water depth over shallow rocks whereas the ship cannot. Also, Surveyors do not have to stay at sea for weeks at a time and can go home to dry land at the end of the day.

On the other hand, limitations of the airplane include lower resolution because the plane is flying so fast. Choppy seas or kelp forests impede data collection, as is true for data acquisition from the ship as well, and the planes cannot collect data from deep waters.

Question of the Day

What type of sea floor is best for anchoring one’s ship?

Answer from Previous Day

Understanding atmospheric sciences is important in navigating ships because the weather affects the ship’s course and ability to conduct business or research every day. Understanding such basic concepts as weather fronts, air mass characteristics, large scale wind systems (ie. Polar Easterlies), and weather phenomenon (ie. hurricanes) can be life saving when out at sea.