Radar and ARPA Manual

302

RADAR AND ARPA MANUAL

(b) Join the own ship position 'C to the target's pos-

ition Ά and produce beyond

l

A\

(c) With compasses at W and radius WO, scribe an arc

to cut CA produced at 0

1

or, if own ship is the

slower (i.e. WO<WA), at 0

±

and 0

2

(d) Join W0

1

(and W0

2

).

(e) Draw CP

1

parallel to W0

1

to cut WA produced at

Pj (and CP

2

parallel to W0

2

to cut WA produced

atP

2

).

(f) P

1

(and P

2

) is the PPC.

For a clearer appreciation of the determination of the

PPC,

Example 7.8 should be drawn out full size and to

scale on a plotting sheet.

7.6.3 The predicted area of danger

(PAD)

The PPC gives no indication of the course which needs

to be steered