Transcript No Slide Title

RADAR PLOTTING
3
2008
CANADIAN
CANADIANCOAST
COASTGUARD
GUARDAUXILIARY
AUXILIARY- -PACIFIC
PACIFIC
End On Situation
CANADIAN COAST GUARD AUXILIARY - PACIFIC
Own vessel 050° at 10 knots
6 minute plot
(1) Find the course you are
going, and draw a line for
your course
In the case of heads up ,
mark 000°
CANADIAN COAST GUARD AUXILIARY - PACIFIC
Own vessel 050° at 10 knots
6 minute plot
(2) Mark the first radar
bearing and range of the
target.
358º R x 2.5 nautical miles.
All bearings are R as they
are relative to your vessel’s
head.
Mark as "O“
Mark time of 1200
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
Own vessel 050° at 10 knots
6 minute plot
(3) After 6 minutes mark the
second radar bearing and
range of the target.
359ºR x 0.77 nautical miles
Mark as “A”
Mark time of 1206
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(4) From "O" draw a line
through "A" and carry the line
well past the centre line on the
screen
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(5) Transfer your course line
to "O" and pull the line down
the sheet
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(6a) Calculate own vessel
distance in plot interval.
To use calculator scale, place
right point of divider on 60
(right end of scale) and left
point on own vessel speed
(10 knots).
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(6b) Move the dividers at this
setting, and place right point
on the plot interval (6
minutes)
The number under the left
point of the dividers will
indicate the distance gone in
the plot interval. (1 nautical
mile).
6 min @ 10 knots = 1.0nm.
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(6c) Lay down 1 nautical mile
on the plot, on own course
vector from “O”.
12:00 O
W
Mark bottom end “W”
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(7a) Connect “W” with “A”.
“W” to “A” represents target
course and distance travelled
in the plot interval.
12:00 O
W
174°R @0.75 nautical miles
To convert this into speed,
place right point of dividers on
plot interval (6 minutes) and
the left point on distance
travelled in that time (0.75
nm)
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(7b) Move dividers so that
right point is on 60 (right hand
end of scale).
12:00 O
W
The reading under the left
point of the dividers will be the
vessel’s speed in knots.
7.5 knots
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(8) Where the line
through “O” and “A”
passes closest to the
centre of the plot is the
Closest Point of
Approach (CPA)
12:00 O
W
In this case very close to
starboard - scraping the
tube.
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:06 A
Own vessel 050° at 10 knots
6 minute plot
(9) The Time to Closest
Point of Approach (TCPA)
is at the tangent point. OA
is 6 minutes.
12:00 O
W
A to TCPA works out at 2.5
minutes = 12:08:30
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:06 A
TCPA
Results
In this case, providing neither you nor the target
vessel alter course or speed:
• the target vessel is proceeding at 050° + 174°
= 224°C at 7.5 knots
• CPA is at 12:08:30 with a collision
CANADIAN COAST GUARD AUXILIARY - PACIFIC
Results – Clear Visibility
• In clear visibility, you are to assume you in an
end on situation and therefore must take
action to avoid collision. Whilst the other
could be taken as a crossing vessel, it is safer
to assume an end on situation.
• There is a risk of collision, and therefore you
must make a bold alteration to starboard.
• The other vessel should do likewise.
CANADIAN COAST GUARD AUXILIARY - PACIFIC
Results – Restricted Visibility
• In restricted visibility, you are required to take
action.
• As in clear weather, a broad alteration of
course to starboard is the best action,
carefully monitoring the actions of the other
vessel.
• A 90 degree starboard alteration would be
best in this case.
CANADIAN COAST GUARD AUXILIARY - PACIFIC
End On Situation
CANADIAN COAST GUARD AUXILIARY - PACIFIC
End On Situation
• If however at 1206 you acknowledge the
other vessel is on a steady bearing, you can
stop and assess the situation.
• The plot will then change to:
CANADIAN COAST GUARD AUXILIARY - PACIFIC
Own vessel 050° at 10 knots
6 minute plot
In this case stopping will only
gain you thinking time, but
does not prevent a close
quarters situation.
You will need to make a 90°
alteration of course to
starboard and increase speed
to comply with rule 14.
You can see immediately he is
doing 224°C at 7.5 knots
CANADIAN COAST GUARD AUXILIARY - PACIFIC
12:00 O
12:06 A