Second vector

Enav222 midterm lessons

METHOD I (PROCEDURES)

ALTER COURSE AND MAINTAIN SPEED

SITUATION: Our ship is on Course 0000 T speed 11 knots.

Our radar is set on 12 mile scale. A contact is observed as follows:

TIME BEARING RANGE 0603 0600 11 miles 0609 0590 9.5

miles 0615 0580 8.0

miles

CHANGE OF COURSE

Find: RCPA TC TCPA TS MCPA Target Aspect MRM DRM SRM

PART 1-

PLOTTING THE 1ST VECTOR (e-r-m)

Oc=0000

OS=11knots

R

M1/0603M2/0609

M3/0615

Tdiff.= 12 minSpd=11kts.

Dist= 2.2miles

RML

X

2.2

Find: RCPA TC TCPA TS MCPA Target Aspect MRM DRM SRM

END of PART 1-

PLOTTING THE 1ST VECTOR (e-r-m)

PART 2-Plotting the 2nd Vector (e-r1-m)

MX BMX TMX RMX NDRM NSRM NTCPA NBCPA NRCPA

Find and Plot the ff:

2.2

e

rm

MX

NRML

NDRM

3miles6miles

WHAT WILL BE OWN SHIP’S NEW COURSE?

2.2

e

rm

MX

NRML

NDRM

NRM & RL

r1

e

rm

MX

NRML

NDRM

NRM & RL

r1

NCo

e

rm

MX

NRML

NDRM

NRM & RL

r1

Nco=054o

RML

DRM

R

MX BMX TMX RMX NDRM NSRM NTCPA NBCPA NRCPA

Find and Plot the ff:

Of change course problems

END

METHOD II (PROCEDURES)

MAINTAIN COURSE AND ALTER SPEED

Own ship’s course could be changed to either

054o or 294o . However, there is a reef to starboard and three ships to port that prevent either course changes.

Required: What other course of action could be taken? Answer: Reduce speed = 5.2knots

CHANGE SPEED PROBLEMS

e

rm

MX

NRML

NDRM

NRM & RLr1

RML

DRM

R

Spd.reduce to 5.2kts.

METHOD III (PROCEDURES)

ALTER COURSE AND ALTER SPEED

Instead of continuing own ship at the speed of

11 knots and instead of changing course to either 054o or 294o we decide to increase speed to 15 knots.

Required: What course change will have to be made so that at 15 knots, the CPA will continue to be 3 miles?

Answer: 065oT

CHANGE OF SPEED AND COURSE PROBLEM

Tdiff.= 12 min

Spd=15kts.

Dist= 3.0miles

r

em

MX

3milesr1

e

NRM & RL

r1

e

NRM & RLmMX

r

NRML

NDRM

NCO=065O

HOW TO PLOT NEW COURSE

r1

e

NRM & RLmMX

r

NRML

NDRM

NCO=065O

END