Elli Simonen:  Survey Launches, July 24, 2023

NOAA Teacher at Sea

Elli Simonen (she/her)

Aboard NOAA Ship Fairweather

July 10, 2023 – July 28, 2023

Mission:  Hydrographic Survey of the Pribilof Islands 

Geographic Area of Cruise: Pribilof Islands, Alaska

Date: July 24, 2023

Weather Data

Location:  56°36.8259’N,169°32.2224’W

Outside temperature: 11°C

Water temperature: 10°C

True Winds: 16kn, 185.4°

Skies: Foggy with Drizzy Rain

Visibility: 5nmSea

Wave: 1-2 ft

Swell Wave: 1 ft

Science and Technology Log

We are currently at anchor off the north shore of Saint George Island and the survey launches are going out daily to survey a portion of the surrounding waters.  I have been on the survey launches twice, each time surveying a different area.

Survey Launch July 22, 2023

The Pribilof Islands are the breeding grounds for more than two thirds of the world’s fur seal population and their numbers peak in July.  Our surveying operations do their best not to disturb the Fur Seals.  I was on a launch that was assigned the harbor.  However, upon entering, we saw a colony of Fur Seals and had to turn back around.  We then went onto survey another area in open water.  Later that morning, the winds increased and all survey launches returned to the ship out of caution for the weather.

view over the edge of a survey launch vessel of the harbor on a small island. it's a cloudy day, and the sky, trees, and water are all shades of blue-gray. the only color comes from the bright orange life ring mounted on the vessel.

Entering the harbor at Saint George

view at a distance of fur seals swimming near the shore of St George island. the fur seals appear as small dark shapes poking out from the water. the land is covered in large gray boulders.

Fur Seals in the Saint George harbor

Survey Launch July 23, 2023

We went out to survey an area closer to shore and were out all day – a good weather day.  We surveyed using set lines; this is where survey lines are parallel and evenly spaced apart. During post survey data processing, these lines of coverage will be used to update soundings on the chart. Set lines are used in areas of shallow water where there is not much bathymetric data, such as the Pribilof Islands.  This process allows the survey team to complete a larger survey area in less time.  

Our surveying boundary close to shore is defined by the navigational area limit line (NALL), which is the distance from shore that vessels can reasonably navigate.  The other boundaries are mapped out by the survey team ensuring coverage of the entire area.  During surveying in addition to depth data, any information about features that can impact navigation need to be noted.  This can include an outcrop of rocks, shipwrecks or a kelp forest.  We did see a kelp forest close to the shoreline during this survey, and indicated that in our data.  Kelp forests can increase or decrease in size depending on the year and water temperature, but generally stay in the same place.

The swath is the width of the survey lines.  During surveying the swath gets larger as the depth increases.  In this survey, as you move away from shore the depth becomes deeper, so the width of the swath increases as well.  This is due to the fact that the MBES angle is fixed and the depth is related to the swath by the tangent function.

photo of a computer screen showing, in a large window, a map of the survey area. black lines surrounded by swaths of bright red, green, or yellow bands of color snake up and down the map, representing the transects surveyed.

Screen showing the set line spacing and data taken near the shore.

cliffs along the shore of St George, as seen from a survey launch. the water is turquoise-colored in the foreground and brownish closer to shore. tall cliffs of black, brown, and gray colors, with some green growth at higher points, rise out of the photo. there are white specks - the seabirds - all over the cliffs.

Close to the shoreline of Saint George.  The color change of the water indicates a kelp forest.  Thousands of sea birds are on the cliffs.

calculations on a whiteboard. at top is a simple depiction of a boat, labeled 'launch.' a triangle extends down from the bottom of the launch toward the seafloor. the top angle (between the lines extending from the launch) is labeled 130 degrees. arrows show the direction of the echosounder pings (labeled MBES) toward the seafloor. The height of the triangle is labeled "depth" and the base "width of the swath."
Below this image is a drawing of a right-angle triangle, one half of the above. The top angle is labeled 65 degrees (half of 130 degrees), the height is labeled "Depth" and the base is labeled "1/2 swath." 
written calculations read: tan (theta) = opposite side length / adjacent side length. tan 65 degrees = (1/2 swath)/depth. (depth)(tan 65 degrees) = 1/2 swath. 2 (depth)(tan 65 degrees) = swath. 2(depth)(~2.1) = swath, ~4.2 (depth) = swath.

How the width of the swath can be calculated.

headshot of Elli on a survey launch vessel. she's wearing a heavy jacket and a Teacher at Sea beanie. we can see St George's island in the background.

TAS Elli Simonen on a survey launch close to shore of Saint George, one of the Pribilof Islands

At the Helm of the Survey Launches

Coxswains are responsible for steering and navigating the survey launches.  They use a variety of instruments and sensors to maintain safety and guide the survey launches over the planned survey lines. The heading is the direction the bow of the ship is pointing, expressed as a degree measurement from 0° to 360°. We were mainly surveying lines that were running north-south and the heading measurement was 0° when we went north and 180° south.

a small black instrument panel showing the heading, currently 002.0 (close to 0).

Heading indicator showing the direction of the survey launch and allows for autopilot.

a compass mounted to a surface on the survey launch. it reads close to 0 N.

Magnetic Compass showing heading on the survey launches.

photo of a computer screen showing a map of the survey area

Screen for coxswains on survey launches showing depth, the water column and survey lines.

two people at the helm of the survey launch vessel. Elli grips the helm while Ashley looks on. we can see gray ocean surface out the windows. the compass is mounted to the dashboard above the helm.

TAS Elli Simonen attempting to steer the Survey Launch with NOAA Corps member ENS Ashley Howell.  It is much harder than it looks!

Personal Log

Day to Day

Most of my days have been spent on the ship or lately, on survey launches.  If I’m on the ship, I usually spend most of the day in the survey room with the survey technicians.  Breakfast is served from 7-8 am, lunch is from 11-12 pm and dinner is 5-6 pm.  Sometimes a movie is shown in the lounge in the evenings, but the other day we streamed the Women’s World Cup to see the USA win their opening game! 

Some of the common areas of the ship

view of the survey room. a large island in the center contains cabinets and a map table. computer desks line the walls. four people sit working at computers, while a fifth stands reading something.

The survey room where all the survey technicians have their work stations.

view of the galley, or kitchen, from the service bar on the outside.

The galley with lunch available

tables and chairs in the dining area. the legs of the chairs have been capped with cut open tennis balls to slow sliding during rough conditions.

The mess, where we all eat meals.

three washing machines and two dryers in the laundry room of NOAA Ship Fairweather.

Washers, dryers and soap are provided for everyone’s use.

Did You Know?

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