Tracking

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Tracking Bearing Drift, Target Angle
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Tracking, Bearing Drift, Target Angle

• AGENDA
• Basic Tracking
• Determination of CPAs
• Bearing Drift
• Target Angle
• Contact Reports
• Applicable reading MBW Ch 5.

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Basic Tracking

• Solving the Contact Tracking Problem
• 1. Read the entire problem and decide on scale.
• 2. Use the largest scale possible that will
  permit the entire problem to be plotted on the
  maneuvering board.
• 3. Once you have selected a scale, be consistent
  in its use.

4
Basic Tracking

• Solving the Contact Tracking Problem
• 4. Plot the M1, M2, etc. avoid plotting
  reciprocals. When a bearing is given, be sure
  you understand to which ship the bearing applies,
  and from which ship the bearing is observed. The
  successive positions M1, M2, etc., indicate
  movement or maneuvering relative to the reference
  ship.

5
Basic Tracking

• Solving the Contact Tracking Problem
• At 0800 a contact bears 280ºT, at a range of
  16,000 yards. At 0815 the same contact bears
  300ºT, at 10,000 yards
• 4. Plot M1 and M2 (points on the moboard the
  correspond to the bearings and ranges of the
  contact)- note, use a 21 scale.

6
D
M2
M1
7
Basic Tracking

• Solving the Contact Tracking Problem
• 5. Solve for DRM, MRM, SRM.
• a. DRM - Solved for measuring true bearing
  between M1 and M2.
• b. MRM - Computed using dividers. Spread
  betweenM1 and M2 and measure the distance
  using the same scale used for plotting M1 and
  M2.
• c. SRM - Computed by dividing distance (MRM) by
  the amount of time between M1 and M2.

8
D
MRM
M2
e
M1
9
Basic Tracking

• Solving the Contact Tracking Problem
• At 0800 a contact bears 280ºT, at a range of
  16,000 yards. At 0815 the same contact bears
  300ºT, at 10,000 yards
• 5a. Find DRM - 073ºT
• 5b. Find MRM - 7,500 yards
• 5c. Find SRM - 15 knots

10
Basic Tracking

• Solving the Contact Tracking Problem
• 6. Plot your course and speed vector (er). e
  is the point from which all actual (true) course
  and speed vectors are drawn (center of moboard
  sheet). r is the reference ship. The
  direction of this vector is the reference ships
  true heading and the magnitude is the speed over
  time.

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MRM
M2
e
M1
r
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Basic Tracking

• Solving the Contact Tracking Problem
• 7. Parallel the DRM line to the tip of your
  course vector er and measure the length of SRM
  along the DRM to form the second side of the
  speed triangle. This vector is labeled rm with
  point m being the maneuvering ship.

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MRM
M2
e
M1
r m
14
Basic Tracking

• Solving the Contact Tracking Problem
• 8. Solve for the maneuvering ships course and
  speed by connecting points e and m. The
  direction of this vector is the maneuvering
  ships course and speed is simply the length of
  you em vector (measured on your speed scale).

15
Basic Tracking

• Solving the Contact Tracking Problem
• At 0800 a contact bears 280 T, at a range of
  16,000 yards. At 0815 the same contact bears 300
  T, at 10,000 yards. Your course is 135 T at
  15 knots
• 8. em - 103 T, 26 knots

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MRM
M2
e
M1
r m
17
Basic Tracking

• Solving the Contact Tracking Problem
• At 0800 a contact bears 280ºT, at a range of
  16,000 yards. At 0815 the same contact bears
  300ºT, at 10,000 yards. Find CPA bearing and
  range
• 9a. CPA bearing (Add or subtract 90º to/from DRM
  to determine CPA Bearing) - in this case subtract
  90º
• 073ºT - 090ºT 343ºT

18
D
S
MRM
90
M2
M1
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Basic Tracking

• Solving the Contact Tracking Problem
• At 0800 a contact bears 280ºT, at a range of
  16,000 yards. At 0815 the same contact bears
  300ºT, at 10,000 yards. Find CPA bearing and
  range
• 9b. CPA Range - measure from the center of the
  maneuvering board to CPA point to determine CPA
  range - 7,500 yards

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D
S
MRM
CPA Range
M2
M1
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Target Angle

• Target Angle
• Target angle is defined as your relative bearing
  FROM another ship. In other words, it is what
  aspect of him you are seeing.
• It allows the shiphandler to determine which
  aspect of another ship is in view and determine
  if a risk of collision exists.
• Target angle True Bearing /- 180 - contacts
  course

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Target Angle Practical
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Bearing Drift

• Bearing Drift
• Bearing Drift is the amount of change of a
  contacts bearing over a period of time. If the
  bearing of a contact does not change over time
  and the range is decreasing, there is a definite
  risk of collision occurring. If there is a
  definite change in bearing over time then there
  is little or no risk of collision.

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0800 0810
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0920
0900
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1000
1030
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Contact Reports

• Captain, this is the officer of the deck. I have
  a contact report. I have a ID ...
• off the starboard bow bearing 033ºR, range
  10,000 yards. His target angle is 305º and has
  steady left visual bearing drift. He is moving
  towards a CPA 10º off the port bow at a range of
  2000 yards in 20 minutes. I evaluate this as a
  crossing situation, we are the give-way vessel.
  I recommend coming right to new course ___. This
  will open the contacts CPA to 5,000 yards.