Parallel indexing is a technique used on radar to monitor a vessel's progress and maintain a safe distance from navigational hazards. It involves drawing parallel bearing lines to reference the vessel's position. Trial maneuvering simulates potential maneuvers on ARPA to avoid collisions by predicting how a vessel's course or speed change would affect surrounding targets over time. It can be run statically to immediately view results or dynamically to display predicted movements in increments. This allows evaluating different maneuvers to determine the safest option.

1. PARALLEL
INDEXING AND
TRIAL
MANEUVER
Group F

2. Learning Outcomes:
1. Describe the Use of Parallel Indexing
on RADAR/ARPA
2. Describe the importance of trial
maneuver as features on ARPA

3. Describe the Use of Parallel Indexing on
RADAR/ARPA
 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.

4. Describe the importance of trial maneuver as
features on ARPA
Introduction:
 Trial Maneuver is one of the Automatic Radar Plotting Aid (ARPA) features implemented in Advanced
Tactical Display system and is used in navigation for collision avoidance. Trial Maneuver simulates the effec
of an own ship maneuver on all tracked targets with or without time delay. While Trial Maneuver is switched
ON, actual target tracking continues in the background without any interruption.
 The Advanced Tactical Display (ATD) system receives and processes data from onboard ship sensors and
displays an unambiguous tactical picture on a Dual Multi Function Console (DMFC). ATD provides facilities
for surface surveillance, navigation, helicopter control, electronic chart feature and other mission critical
warfare functions and assists the ship staff in the decision making process. The ATD system is designed
primarily for small modern warships. Ship data as well as tracked target data is presented on the display.
ATD is interfaced with four RADAR systems and has a Video Extractor and Tracker (VEXT) which generate
surface and air targets.

5. Describe the importance of trial maneuver as
features on ARPA
Descriptions:
 Its feature simulates the effect of own ship's movement against all tracked targets, without interrupting the
updating of target information.
 It is available for use with the tracked target and AIS functions. For more accurate results, use relative
motion and sea stabilization (ground tracking).
 Trial maneuver feature has been designed for both true mode and relative mode of the ship Plan Position
Indicator (PPI) display. In true mode, actual position of the own ship is displayed with its actual speed.
Targets are also displayed with their actual velocity vectors in the true mode. In relative mode the own ship
position is always at the center of PPI and targets are displayed with their relative velocity vectors. Using
Trial Maneuver the operator can vary the speed, course and simulation time(delay) of the own ship and see
at what course and speed the ship needs to be steered in order to avoid collision with the surrounding
targets/vessels. To predict a potential close-quarters situation, we make use of Closest Point of Approach
(CPA) and Time to Closest Point of Approach (TCPA) concepts.

6. Types of Trial
Maneuver

7. Types of Trial Maneuver:
Static
● The static trial maneuver shows the
relationship between your ship and TTs at the
completion of the trial maneuver. Enter
expected course and speed and delay time
until start of a maneuver and the expected
position of your ship and TTs at the end of the
trial maneuver are shown on the display.
● By shortening and extending the trial time you
can find the safe time to make a maneuver.
Thus, the static trial maneuver will be
convenient when you wish to know the
maneuver result immediately

8. Types of Trial Maneuver:
Dynamic
 It displays predicted positions of the TTs and own ship. You enter
own ship's intended speed and course with a certain "delay time."
Assuming that all TTs maintain their present speeds and courses, the
targets' and own ship's future movements are simulated in one-
second increments indicating their predicted positions in 30-second
intervals as illustrated on the left.
 The delay time represents the time lag from the present time to the
time when own ship will actually start to change her speed and/or
course. You should therefore take into consideration own ship's
maneuvering characteristics such as rudder delay, turning delay and
acceleration delay. This is particularly important on large vessels.
How much the delay is set the situation starts immediately and ends
in a minute.
 In the example shown on the left, own ship will advance straight
ahead (even after a maneuver) for a delay time of 2:30 and alters
speed and course until operator-specified intended speed and course
are achieved (position OS7 in this example).

9. THANK YOU