Assignment 1.1: Nautical Chart

Instructions

Nautical Chart

Developed by the Channel Islands National Marine Sanctuary

A nautical chart is the type of map used by mariners and other people interested in navigating bodies of water. Just as you might use a road map when planning a trip over land in a car, you can use a nautical chart when planning a trip over sea in a boat. Nautical charts are different from other kinds of maps in that they primarily describe geological features that are, for the most part, underwater and impossible for us to see in their entirety. Information on points of interest to the maritime navigator that can be found on a nautical chart include:

• Natural features

• Depth and nature of the seabed

• Tides and currents

• Rocks, wrecks, and sub-surface obstruction;

• Ports and marinas

• Land features, such as tunnels, airports, and bridges

The development of 3-D bathymetric charts provides a clearer visual picture of what the relatively abstract lines and numbers on a traditional nautical chart truly represent. 3-D bathymetric charts significantly aid us in our efforts to visualize the bathymetry of the ocean floor more accurately.

Necessary Materials

• Nautical Chart

• Ruler/straight edge

Section 1: Latitude and Longitude

In common with virtually all other maps, nautical charts have lines of longitude (also called meridians) and latitude (also called parallels) expressed on them. Together these sets of lines create an imaginary grid that can be used to locate any point on Earth.  The meridians of longitude run from north to south on a globe from pole to pole and are measured in degrees. Each degree is divided into 60 parts called minutes. Each minute is divided into 60 seconds of longitude. If you were to cut along the meridians of an orange you would be cutting wedges. 0 degrees longitude is called the prime meridian and is the longitude line that runs through Greenwich, England. The rest of the meridians run 180 degrees to the east and 180 degrees to the west of the prime meridian. For example, New York City has a longitude of 74 degrees west, which means, if you headed west from Greenwich, you would reach the same longitude as New York once you had come to your 74th line of longitude.

The latitude lines, or parallels, run around a globe from east to west. They are also measured in degrees, which in turn are divided into minutes, which in turn are divided into seconds. The parallel that lies at 0 degrees of latitude is also called the equator. The rest of the parallels run 90 degrees north of or 90 degrees south of the equator. If you were to cut along the parallels of an orange, you would be cutting disks. To differentiate between the two, you can remember that the lines that run parallel to one another are called parallels or lines of latitude.

Information on latitude and longitude is typically written something like this: 42° 57’N 94° 45’W. The latitude comes first (42°57’N) and, in this particular case, lies 42 degrees and 57 minutes north of the equator. The longitude comes second (94° 45’W) and, in this case, lies 94 degrees and 45 minutes west of the prime meridian.

Procedure:

• Take out the nautical charts and give yourself some time to get oriented to the charts

• Identify the lines of latitude and longitude.

Section 2: Compass Rose

A compass rose is a symbol on nautical charts that consists of two or three concentric circles a couple of inches in diameter. Each circle is marked in degrees. The degrees correspond to what is called a compass heading. For example: 0°/360° corresponds to North, 90° corresponds to East, 180° corresponds to South, and 270° corresponds to West. All vessels and almost all objects move in more than just the four directions of North, South, East, and West. It is for this reason that the compass rose is divided into 360°. The outer circle on a compass rose is aligned with 0° at true north and is usually subdivided in intervals of one degree.

The next circle has 0° aligned with local magnetic north and is also subdivided — but usually in a different interval. On the smaller chart used in this activity, the compass rose consists of only one circle and is aligned with magnetic north.

Procedure:

• Locate the compass rose on the nautical charts.

• Determine if the Channel Islands run north-south or east-west.

• Align a ruler or straight edge so it passes through Loon Point (near Summerland on the mainland) with the center of the compass rose (indicated by a small cross in the center of the circle) and the 165° marker on the compass rose.

Procedure:

• Find the oil rigs, HERITAGE and GAIL, given their latitude and longitude of 34° 21’N 120° 17’W and 34° 08’N 119° 24’W, respectively. (Hint: Oil rigs are represented by a small black square.)

• Locate the Channel Islands National Marine Sanctuary Boundary (Hint: Six nautical miles off the four northern Islands and Santa Barbara Island).

• Find the approximate latitude and longitude of the East Santa Barbara Channel Weather Buoy.

• Find either Gaviota Canyon, Carpinteria Creek, or Ventura Harbor (they are located off the coast of California) and then plot a course to

• Prisoners Harbor on Santa Cruz Island.

• Identify an oil rig, except HERTIGATE and GAIL, located in the Santa Barbara Channel.

Deliverables:

In a separate word processing document, answer the 10 questions below. Refer to the attached rubric to see how you will be assessed. Remember, direction units are important!

Section 1 Questions:

1. State what natural feature is found at 34°N 120°15’W.

2. Find another feature of this type along the mainland coast. State the name of the feature and give its latitude and longitude.

Section 2 Questions:

1. Does the Channel Islands run north-south or east-west? Explain how you determined this.

2. What is the compass heading from Loon Point to the 165º marker?

3. If you traveled in this direction from Loon Point, would you hit land? If so, where?

4. If you were to turn around and head back, what would your compass heading be to reach Loon Point?

Section 3 Questions:

1.  How many, if any, oil rigs are within the sanctuary boundary? What is the name of those platforms? The names are in CAPS surrounded by quotes.

2. What is the approximate latitude and longitude of the East Santa Barbara Channel Weather Buoy?

3. Identify the location you selected (Gaviota Canyon, Carpinteria Creek, or Ventura Harbor) and give its latitude and longitude. Then give the compass heading you’d travel to get from your select location to Prisoners Harbor.

4. Give the name of the oil rig you selected and give its latitude and longitude. Give the compass heading you’d travel to get from Prisoners Harbor to your chosen oil rig.

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