PARALLEL INDEXING
TECHNIQUE
Name : JUMAD, AL-BHENJO M
Yr./Section: MTS2-A1
What is Parallel indexing ?
 Parallel indexing is
a technique used as a measure
to monitor the progress of a vessel on the track
and to minimize the cross track distance and to
keep vessel at a safe distance from the shoreline or
rock.
The
basic principle of this method is that
in order to maintain and follow a
particular course – a bearing line drawn
parallel to the original course with a
known and fixed perpendicular distance
between both the lines is used as a
reference.
 The
increase or decrease of the perpendicular
distance between the bearing lines drawn
parallel to course-line and ship’s position at
any time will indicate cross track deviation
from the initial planned course and thus
advise a mariner if he/she is falling out of a
traffic lane, entering a traffic separation zone
or closing in to a navigational danger.
Parallel indexing technique can be used as it is provided
in the options menu of marine radar where distance
between parallel lines can be fixed and it can also be set to
maintain safe distance from two fixed objects
simultaneously on either side of a vessel.
Upon selecting Parallel Index lines in options menu – a
set of floating lines parallel to each other appears on the
screen.
The orientation of these lines can be set by using the EBL
marker and the distance between these lines adjusted by
the VRM marker.
PARALLEL INDEXING, THE
ADVANTAGES AND USES DURING
COASTAL NAVIGATION AND
APPROACHES / DEPARTING PORT
COASTAL NAVIGATION USING
PARALLEL INDEXA
Advantage

While a ship follows course to steer, parallel
indexing ensures it always remains at a fixed distance
from a hazard. Thus parallel indexing is a method to alert
mariner that he has come close to a navigational hazard.
Disadvantage

Parallel indexing from floating objects cannot be accepted
unless they have been first checked for a position. A
floating object will not give an accurate position.
APPROACHES USING PARALLEL INDEXA
Advantages

Parallel indexing is a technique used as a measure to monitor
the progress of a vessel on the track and to minimize the cross
track distance and to keep vessel at a safe distance from the
shoreline or rock or coastal waters, narrow canals, river passages
or port and harbor approaches.

Does it have no disadvantages
DEPARTING PORTPARALLEL INDEXA

Parallel Indexing can be used to maintain safe distance
alongside the main stages/principles of passage planning. This is
done to ensure that the ship sticks to the required routes for
reaching the port of destination. After departure, the speed is
adjusted based on the ETA.

While transiting a traffic lane or following a traffic separation lane
or passing a shoreline/rock, close by vessel must be kept on the
track planned and thus cross track distance should be zero or kept
to minimum as the available sea room is less to avoid a hazard or
danger.