radar plotting- multiple targets
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radar plotting
Transcript of radar plotting- multiple targets
In multiple targets (e→r) and (e→r1) has the same distance and parallel to each other in every vector triangle when plotted, has the same time of observation and TMx.
Sample Problem:OC = 015°OS = 14 kts.
Target Observations
A B C
Time B D B D B D
1211 H 350° 12 mi 070° 12 mi 111° 10.7 mi
1223 H 348° 9.5 mi 070° 9.5 mi 113° 8.1 mi
When dangerous target range 6 miles, you alter course to 060°T starboard at the same time change speed, so that the target pass ahead your vessel on 2 miles danger zone.
What is the dangerous target?
NSrm: NDRM: NBCPA: NCPA:
A= A= A= A=
B= B= B= C=
C= C= C=
1. TMx =2. NOS =
OC=015°
OS=14kts
R
1. Plot OC and take note OS.
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
M1 1211H
M2 1214H
m
r
m
r
m
R
r
2. Plot the bearing and distance of all the targets.
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
M1 1211H
M2 1214H
m
r
m
r
m
R
r
3. Plot the RML and find the Srm of all the targets.
T(diff) = TM2 – TM1
= 1223H – 1211H= 12 min
SRM = [D(MRM)÷T] x 60= (2.5÷12) x 60= 12.5 knots
T(diff) = TM2 – TM1
= 1223H – 1211H= 12 min
SRM = [D(MRM)÷T] x 60= (2.5÷12) x 60= 12.5 knots
T(diff) = TM2 – TM1
= 1223H – 1211H= 12 min
SRM = [D(MRM)÷T] x 60= (2.5÷12) x 60= 12.5 knots
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
M1 1211H
M2 1214H
m
r
m
r
m
R
r
4. Bring OC line to r of all the targets and make a line from r opposite to your OC.
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
M1 1211H
M2 1214H
m
r
e m
r
e
m
R
r
2.8 miles
5. Form the vector triangle.
D(e-r) = (OS x t) ÷ 60= (14 x 12) ÷60= 2.8 miles
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
M1 1211H
M2 1214H
m
r
e m
r
e
m
R
r
6. Identify which among the target is the most dangerous, based on your COLREG (International collision regulation)..
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
Mx
r
Mx
TMx=1240H
3.5 miles
7. Draw danger zone, locate the Mx and draw your NRML on the most dangerous target (Target “B”), the find the TMx.
NBCPA = NDRM + 90°= 270° + 90°= 000°
TMx = [D(MMx) ÷ S(Srm)] x 60 + TM2
TMx = (3.5 ÷ 12.5) x 60 + 1223H= 17min + 1223H= 1240 H
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
Mx
r
8. Locate r1 of the most dangerous target (Target “B”).
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
Mx
r
4.9 miles
9. Once r1 has already obtained, connect it to m and find for NSrm.
NSrm = [D(m-r1) ÷ t] x 60
NSrm = (4.9 ÷ 12) x 60= 24.5 knotsor 25 knots
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
Mx
r1
r
10. Connect your r1 to e and transfer it to all other target. (Same e-r1 because it is your NOC and NOS.
NOS = [D(e-r1) ÷ t] x 60
NSrm = (3.9 ÷ 12) x 60= 19.5 knotsor 20 knots
3.9 miles
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
NSRM=15.5kts
Mx
NSRM=27kts
r1
r
5.4 miles
3.1 miles
11. Connect r1 to m on all other target and find for NSrm.
NSrm = [D(m-r1) ÷ t] x 60
NSrm = (3.1 ÷ 12) x 60= 15.5 knots
NSrm = [D(m-r1) ÷ t] x 60
NSrm = (5.4 ÷ 12) x 60= 27 knots
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
NSRM=15.5kts
Mx
TMx=1240HMx
NSRM=27kts
r1
r
Mx
TMx=1240H
3.7 miles3.5 miles
12. Locate Mx on all other target by finding distance m-Mx.
(m-Mx)D = [S(Srm) x t(TMx-TM1] ÷ 60= [12.5 x (1240H-1223H)] ÷ 60= (12.5x17) ÷ 60= 3.5 miles
(m-Mx)D = [S(Srm) x t(TMx-TM1] ÷ 60= [13 x (1240H-1223H)] ÷ 60= (13x17) ÷ 60= 3.7 miles
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
NSRM=15.5kts
Mx
NSRM=27kts
r1
r
Mx
TMx=1240H
MxTMx=1240H
13. Once the Mx has been obtained, bring your r1 – m at Mx and draw your NRML and find for the NDrm, NBCPA and NCPA.
NBCPA = NDRM + 90°= 235° + 90°= 325°
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
NSRM=15.5kts
Mx
TMx=1240HMx
NSRM=27kts
r1
r
Mx
TMx=1240H
13. Once the Mx has been obtained, bring your r1 – m at Mx and draw your NRML and find for the NDrm, NBCPA and NCPA.
NBCPA = NDRM - 90°= 285° - 90°= 195°
OC=015°
OS=14kts
M1 1211H
M2 1214H
M1 1211H
M2 1214H
SRM=12.5kts
SRM=12.5kts
SRM=13kts
e
NRML
NDRM=270°
M1 1211H
M2 1214H
NB
CP
A=
00
0°
TMx=1240Hm
r
e m
r
e
m
R
r1
NSRM=25kts
NOS=20kts
r1
NSRM=15.5kts
Mx
TMx=1240HMx
NSRM=27kts
r1
r
Mx
TMx=1240H
1. TMx = 1240H
2. NOS = 20 knots
NSrm: NDRM: NBCPA: NCPA:
A= 15.5 kts. A= 235° A= 325° A= 6 mi
B= 25 kts. B= 270° B= 000° C= 1.2 mi
C= 27 kts. C= 285° C= 195°
