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Lesson 3A: Basic Plotting

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Lesson 3A: Basic Plotting

- AGENDA:
- Basic chart features
- Traffic separation scheme
- Visual aids
- Tabulated depth charts
- Scales

- Plotting on a chart

- Basic chart features

CHART NOTES, CHARACTERISTICS

AND SYMBOLS

- Traffic separation Schemes:
- Indicate outbound and inbound waterways.
- Magenta in color

Traffic Separation Scheme

CHART NOTES, CHARACTERISTICS

AND SYMBOLS

- Navigation Aids:
- Aids with sound and visual characteristics. Listed and labeled on chart
- Usually used as primary navigation
- aids for Visual or Radar.

Visual Aids’ Characteristics Label

CHART NOTES, CHARACTERISTICS

AND SYMBOLS

- Notes located throughout the chart give detailed descriptions of danger, obstructions, depths, overhead clearances, etc.

CHART NOTES, CHARACTERISTICS

AND SYMBOLS

- Scale Conversion Tables:
- Used for measuring distance (based on the scale of chart being used).
- Used for converting U.S. system of measurement to metric, etc.

Tabulated Depths

NEVER use the longitude

scale to determine distances

on a chart.

Navigation Plot: A graphic plot of the movement of a vessel suitably labeled with respect to time, direction, and speed.

TERMS AND DEFINITIONS

Course –The direction in which a vessel is steered or “intended” to be steered.

Designated as True or Magnetic.

TERMS AND DEFINITIONS

Track – The path of intended travel

with respect to the earth as drawn on the

chart.

Speed of Advance (SOA) – The speed intended to be made good along the track.

- The average speed in knots which must be maintained during a passage to arrive at a destination at an appointed time.

TERMS AND DEFINITIONS

PIM-

- Planned track movement based on required SOA
- USS Indianapolis
- Indicated every 4 hours
- Needed for ALL Voyage Plans
- PIM symbol must be different from standard navigation symbols. Ex:

1200Z PIM

- Nautical Mile – A unit distance used principally in navigation. 2000 yards equals one Nautical Mile.
- Knot – A unit of speed equal to 1 Nautical Mile per hour.

Distance of 1 NM

1 Degree = 60 NM

(Nautical Miles)

1 Minute =

1 Nautical Mile

DISTANCE ALWAYS MEASURED ON LATITUDE SCALE!

10 NM

- View Overall Track (Big Picture)
- Use a small scale chart that encompasses the overall area
- Great Circle Sailing
- General (International)

- Use a small scale chart that encompasses the overall area

If transiting open ocean

LABELING

1. Visual fix is plotted as a circle.

2. Electronic fix is plotted as a triangle.

3. DR is plotted as a half circle.

4. EP is plotted as a square.

5. Composite is plotted as a circle with a triangle inside the circle.

LABELING

6. Course is labels on top or above the track line. Referenced in 3 digits and always labeled “T” for TRUE and “M” for MAGNETIC.

7. Speed is labeled below the trackline and always expressed in KNOTS.

8. DR Time is labeled at an angle to the track line.

9. Fix Time is labeled in a straight line to the fix.

COURSE EXAMPLE

0900

C-090ºT (080ºM)

S-10 KTS

D-1510 YDS

30

1000

TRACK EXAMPLE

C-090ºT(080ºM)

S-10 KTS

D-1510 YDS

090705Z

090700Z

- Step 1 - Examine the latitude scale on side of the chart closest to the desired position.
- Step 2 - Place the metal point of the compass on the reference parallel.
- Step 3 - Spread the compass to reach the desired latitude and make a mark.

- Charted Latitude and Longitudes are based on the SCALE of the CHART itself.

- Step 4 - Examine the longitude scale on side of the chart closest to the desired position.
- Step 5 - Place the metal point of the compass on the reference meridian.
- Step 6 - Spread the compass to reach the desired longitude and make a mark.

- Step 7 - Locate the reference parallel and meridian intersection and lightly mark the reference parallel with the longitude marked position.
- Step 8 - Without changing the spread of the compass, place the metal point of the compass on the reference meridian.

- Step 9 - Remeasure latitude on the latitude scale and place the metal end on point and swing a arc so that in crosses the one made for longitude.
- Step 10 - Mark the desired position where the two arcs crossed( intersected) and label the position.

Plotting Positions on different scales of charts.

Coastal Chart

Degrees, Minutes and tenths of a Minute

40 03.9 N

24 51.8 E

1.5-12

D = S x T

T = D / S

x

S = D / T

D = S x T

Distance Equals Speed Multiplied By Time.

yds = 12.0 kt x 3min

1200

S = D / T

SPEED REQUIRED EQUALS DISTANCE DIVIDED BY TIME

kts = 12.0 nm / 36m

20.0

T = D / S

TIME REQUIRED TO TRAVEL 400NM EQUALS DISTANCE DIVIDED BY SPEED.

= 1500yds / 15.0kts

3 min

- Using chart 12245 plot the following position
- 76º 21’ 36” N
- 36º 57’ 50.5” W
- Label as Anchorage 1
DO NOT ERASE THIS MARK!!