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DREPTLOPTCOP

Chapter 4 covers the concepts of dead reckoning, estimated position, transferred line of position, and transferred circle of position in navigation. It explains how to calculate and plot the dead reckoning position and estimated position while considering factors that may affect the vessel's course. The chapter also discusses the importance of accurately plotting positions and the potential errors that can arise in navigation.

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13 views12 pages

DREPTLOPTCOP

Chapter 4 covers the concepts of dead reckoning, estimated position, transferred line of position, and transferred circle of position in navigation. It explains how to calculate and plot the dead reckoning position and estimated position while considering factors that may affect the vessel's course. The chapter also discusses the importance of accurately plotting positions and the potential errors that can arise in navigation.

Uploaded by

shanksshen
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Chapter 4

POSITION & POSITION LINES:


DEAD RECKONING,
ESTIMATED POSITION,
TRANSFERRED LOP,
TRANSFERRED COP
OBJECTIVES:
At the end of the session, the students will be
able to:
state the meaning of the following:
* dead reckoning position
* estimated position
* transferred line of position
* transferred circle of position
Generate dead reckoning position
Plot estimated position on a chart/plotting
sheet
DEAD RECKONING:
The process by which the ship is carried
forward by courses and distances from the
last known fix without taking consideration
of the other factors that may affect the
vessel.
DEAD RECKONING POSITION (D.R.)
The calculated position so found by this
process
A position that has been worked up from
the last position and makes no allowance
for current or leeway.
How to plot D.R. position?
Plot the fix (known or well-determined pos.)
Plot your course steered (true) from the fix
Measure the distance run through the water
for a particular time using the formula D=SxT

NOTE: DR position is plotted without the


consideration of the internal/external
forces that may affect the vessel.
FIX
COURSE
AND
DISTANCE

D.R.
COURSE &
D.R. DISTANCE

FIX
When to plot D.R.?

Whenever the course is changed


When a fix is obtained
When the next waypoint is known

ERROR OF THE D.R. AT THE TIME OF FIX


 The difference between the OLD D.R. and
the NEW FIX
Factors that make this D.R. erroneous:

Error in point of departure/fix


Deviation errors
Bad steering
Errors in distance
Leeway
Current
ESTIMATED POSITION (E.P.):

Best estimate of the ship’s position after


consideration is made of the effects of:
* wind * leeway
* current * bad steering
A modified D.R. position by the best
information available
Is plotted as per judgment of the navigator
 After obtaining fix at 1400H,
the OOW plotted the D.R.
using the 300˚ T/C & distance
of 10 Nm (speed =10kts, time
interval=1hr). After an hour,
E.P. point A bears 045˚ and the
D.R. wind is blowing towards North.
What would be the v/l’s E.P.?

DISTANCE COURSE
D=10’ T/C=3000

FIX
TRANSFERRED LOP:

The process of
Transferred LOP
transferring LOP
using the: Dist.= 13Nm
 * LOP
* course T/C=335˚

* distance
traveled
* time interval Pt. A bears 270˚
* speed
TRANSFERRED COP:
The process of
transferring the Pt. B has a
circle of position dist = 1Nm
using the:
Course 180˚
* COP
* course Distance =2Nm

* distance
traveled Transferred
* time interval COP

* speed

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