ship navigation – Page 2 – NOAA Teacher at Sea Blog

June 16, 2006March 18, 2021

Jacob Tanenbaum, June 16, 2006

NOAA Teacher at Sea
Jacob Tanenbaum
Onboard NOAA Ship Miller Freeman
June 1 – 30, 2006

Waves washing over the bow of NOAA Ship MILLER FREEMAN

Mission: Bering Sea Fisheries Research
Geographic Region: Bering Sea
Date: June 16, 2006

Weather Data from the Bridge

Visibility: 14 miles
Wind Speed: 27 miles per hour
Sea Wave Height: 7 feet
Water Temperature: 41.7 degrees
Air Temperature: 42.4 degrees
Pressure: 1013.8 Millibars

Personal Log

NOTE: We will arrive in the port of Dutch Harbor, Alaska on June 20. As the project draws to a close, I would like to evaluate how effective it was. There is a link to an electronic survey. I would like to ask students, teachers, parents, and other visitors to the site to take a few moments to let me know what you think of this idea. The survey is all electronic and only takes a minute or two to complete. Thank you in advance for your time. Click here to access the survey. How do you find your way around when you can’t see any land? I spent some time with Ensign Lindsey Vandenberg, on NOAA Ship MILLER FREEMAN.

Every 30 minutes or so, the bridge officers take a “fix” on their position. How do they do it? When they are out at sea, they take the latitude and longitude from the GPS and plot their exact position on a chart. A GPS is a machine that uses satellites to display the exact longitude and Latitude on a screen. The charts also have the latitude and longitudes written on them, but there is a problem. The longitude and latitudes scales on the chart are on the side and bottom of the chart, not where the ship is located. Every so often, there is a line across the entire chart. The navigator must use a tool, like the same compass you might use in math class, to mark the distance to the exact point on a scale from a line on the chart. She can then use the same tool to mark the distance in the part of the chart where we actually are. This must be done for both the longitude and latitude of the ship.

When we are near land, we can use Terrestrial Navigation. This means we can use the distance to an object on the shore, such as a lighthouse, to find out wherewe are. With a large ship close to shore, it is very important that we know exactly where we are so that we don’t wind up in shallow water. Ensign Vandenberg uses a tool called an alidade to help her. She puts the alidade over a large compass outside of the ship. The instrument reflects the compass into the viewer so she can see both the object on shore and the exact compass heading. If she takes a few bearings to objects on shore, she can use tools to chart her exact position on the chart.

Science Log:
I’ve been asking many of the people on the ship what becomes of the data that we are collecting. This survey will be used to set quotas for one of the most important fisheries in the world. Here is how it works. If too many fish are caught in an area, there will not be enough fish left for the species to come back the next year. That is bad for the fish, and bad for the fisherman. To prevent this “overfishing,”. A quota, or limit to the number of fish that can be safely caught, is established. Methods are put in place to make sure that all fishing boats in the area respect the quotas. Do you want to learn more? Take a look at this short video on the subject.

Question of the Day:
It is about 8:00 AM on Saturday morning. If the ship uses 2100 gallons of fuel a day, how many gallons of fuel will we need to get to Dutch Harbor on Tuesday Morning at about 8:00 AM?

Answers to Yesterday’s Question:
If our ship wants to do a trawl 50 meters below the surface, how much wire would it need.

The ship must put out two feet of wire for every one foot of depth. So you have to multiply 50 x 2 which gives 100 meters of wire. Each net has, not one, but three wires holding it to the ship. So you would need 3 wires. All three are 100 meters in length. That gives us 300 meters of wire to do our trawl.

Answers to Your Questions:
Hello to all who wrote today.

Colin, no seawater on the equipment yet. They have a couple of computers in the lab where we process fish that can be drenched with water and will still work. Maybe I need one of those.

Mrs. Z. Click here to see the route we have taken so far. I do not think it will give you exact miles, but you can get a good idea of our total.

Thanks for writing.

August 17, 2005March 18, 2021

James Miller, August 17, 2005

NOAA Teacher at Sea
James Miller
Onboard NOAA Ship Rainier
August 13 – 27, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: August 17, 2005

Weather

Sky: Clouds and rain, low 60’s
Wind: 10-15 kts.
Seas: 6 – 8 foot
Itinerary: Should arrive in work area tonight (9:30pm). Anchor in Fish Range Bay on peninsula.

Science and Technology Log

Went up to the bridge last night prior to going to bed. There’s usually an officer and three crew on a rotating four-hour shift schedule. It’s reassuring that there is so much redundancy regarding navigational equipment. The officer on duty (OOD) is constantly checking our position on the chart and comparing it to the radar, and GPS chart plotter. He also does some quick time, distance, speed calculations to determine where we should be at half hour increments, these he marks on the chart (good lesson potential).

We also had a good conversation regarding compass headings. Typically, smaller boats navigate using magnetic compasses and therefore always steer toward magnetic north. The problem with magnetic north is that charts use true north (north pole) and depending where you are in the world there is a deviation between true and magnetic north (close to 20 degrees where we are). The ship is fitted with both magnetic and gyrocompasses. The gyro compass points towards true north but requires power. The ship uses the gyrocompass to navigate but would have to fall back on the magnetic compasses if the ship lost power (which is highly unlikely).

I met with LT Ben Evans and Commanding Officer Guy Noll after lunch for a briefing. They were interested in what specific classes I teach, and the things I wanted to get out of the cruise. They also briefed me about the RAINIER’s mission and where we would be working. They showed me a chart in and around Mitrofania Island. Charts will typically have depth soundings (in fathoms) every ¼ inch or so. The map they showed me had a lot of white space with only a few limited depth soundings. The reason for this is because the area is literally uncharted. Very few ships or even fishing vessels come into the area because, in Alaska, the ocean bottom rises very quickly and they are concerned about running aground. This is where the RAINIER comes into play. Its mission is to collect the data to eventually be put on charts. It sounds like an easy task, however, the process is very complex and lengthy. I’ll be learning more about the details of this process over the next week and two days.

Seeing the charts really gave me a good visual of where we are heading and the importance of the RAINIER’s mission. I plan on putting together a bulletin board in my classroom detailing my experiences and the charts would be an excellent addition to it. I wrote down the chart numbers and asked Navigational Officer Pounds if they had any old ones on board they could part with. He’s going to check for me, but if they don’t, I’ll just order them through NOAA.

Just before dinner I attended a briefing for the survey crew. These are some of the things I learned:

1) This leg is considered a clean-up leg since they worked the area for three weeks on the previous leg. Apparently there are five open sheets (sheets are designated areas that need surveying) that need to be completed.

2) There is an unstable weather pattern in the area and it will obviously determine whether or not we can finish in this area on this leg.

3) In addition to taking soundings, we will need to pick up a tide gauge and differential GPS station that they put on the island the last leg.

4) The tide gauge sends tide information via satellite to NOAA Headquarters. Again, very little is known about this area including tide variations.

5) As I understand it, the GPS stations that are set up on the Alaskan peninsula are too far away to be effective, therefore, the differential GPS was temporarily set up on Mitrofinia Island so that the RAINIER could navigate better while working in the area.

6) We will initially be anchoring north of Mitrofania Island in a protected bay on the peninsula called Fish Range Bay. We will spend a day or two there and then move to Cushing Bay, which is on the north side of Mitrofinia Island.

7) They once again reiterated the fact that they are a bit short-handed this leg and will be relying on me to be part of the launch crews. I should expect very long days for about 5-6 days.

Personal Log

I slept very well last night. I was in such a deep sleep that I almost missed breakfast. I guess it was the rocking of the ship. The seas are about 6-7 foot and the boat seems to handle it well. We’re going with the wind so it’s more of a soft but rolling ride. It’s kind of a funny sight seeing everyone on board bouncing off the walls as they walk down a hallway. My cabin is on the port side on the bottom of the ship, so you can hear the water rushing by the hull, a bit eerie. Although, I guess it’s much better than a cabin next to the engine room. I’m feeling fine; in fact, I had a big greasy breakfast and a hot dog for lunch. You can be assured I would not eat that kind of food if the seas were getting to me. I feel bad for another visitor onboard whom I’m friendly with. Unfortunately, he hasn’t found his sea legs yet, but I’m sure he’ll feel better when we get the Fish Range Bay tonight.

The other bad side to this weather is the visibility is terrible. On our right (starboard) has been the Alaskan Peninsula, and we passed Kodiak Island to our left (port) but could barely make them out. I hope the weather clears at some point so I can get some good pictures. I promised my wife!!!

I have to get a good night’s rest tonight because I’m scheduled to be out on a launch for close to 9 hours tomorrow. After dinner I’ll be working with the survey crew to analyze the data. So it’s going to be a long day, but I’m looking forward to it.

July 21, 2005March 18, 2021

Tamil Maldonado, July 21, 2005

NOAA Teacher at Sea
Tamil Maldonado
Onboard NOAA Ship Fairweather
July 18 – 28, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific
Date: July 21, 2005

Science and Technology Log

Navigation… Today we studied latitude and longitude and their relation to each other. We used geometry concepts like degrees, parallel lines, circles, transversal lines, alternate internal angles, and alternate external angles. We used charts, grids, compasses, and different instruments from the bridge. We shared information about how people were measuring latitude and longitude in olden days and how it is measured nowadays. We discussed mathematical relations of degrees, minutes, seconds and nanomiles. One question for you… how are the Sun and angles utilized in calculating latitude and longitude?

Hydrography Lab… I got the chance to look at some hydrographic data, and to get to know information about the different sonars they are using to retrieve all the data. The Difference among sonars is the beams per particular time that sonars are shooting. FAIRWEATHER ship has a sonar that does 160 beams in 220 microseconds. They also use little boats to go to shallower grounds and have sonars of 111 beams and 101 beams per 220 microseconds. They get a huge amount of data coming into their computer devices, and then they use software called Cares Hips and Sips, which recollects all the data plotting it in two dimensional and three dimensional grids. It also used colors to identify how deep it is in that particular region. Blue is used for deeper regions, while red is used for shallower regions. There are a few issues that needed to be corrected. There is some noise in the data due to salinity, movement of vessel, and tides. An important key is that they need corrections on real time. To correct this data, they use another instrument like POSMV. After all data is collected they could go back and get pictures per zone, and per beam too. Therefore they could analyze all data and get correct information. They also use satellites called GPS – Global Positioning System. In the future I will be talking to Richard (the ET- Electrical Technician) about all satellites they are using on board.

FOCI… They had some problems today too with the computer system, so in order to know about the depth of the net in the seawater they have to calculate “by hand” using charts. For an approximately 45 degree angle measured between the cord holding the net and perpendicular to the floor of the ship, you need how much wire is out, how wide the circle is that holds the wire, how many revolutions, and if there is a linear relationship between this information and the desired net depth. For example if you want the net 40 meters deep vertically then you need 57 m wire out. Remember that the boat keeps moving at certain time and that will give you an angle (in this case you need the angle to be approximately 45 degrees). Scientists use available charts for this information, but we can actually calculate it manually.