Appendix ③− ２

Navigator Education - Navigation Questions and Answers

Navigation for vessels crossing (answer)

Case１

Miles
8

Other vessel: 15kts

3.5 nautical miles

7614 nautical miles
40˚ (approx.)
Bearing changed slightly to
starboard due to vessel
crossing.
On this heading, the vessel willpass
in approximately 0.3 nautical
miles (in approximately 36minutes).
Vessel travelling at 18kts. Othervessel travelling at 15kts.

After
9 minutes

5.
5.5 nauticalmiles

3

4.3 nauticalmiles

1.6 nautica
nauticalmiles
Aft r 27 minutes
After
Approxima ely 8˚Approximately
after coming on
port beam

4.1 nautical
auticalmiles

After 18 minutes
Approximately 46˚after coming on
port beam

m nutes
After 9 minutes
A p oximat ly 3˚˚Approximately
after coming on
po t beam
eam
port

1

After 37 minutes
Crosses course ofother vesselAfter
36 minutes

8 nautical
miles

2

No other vessels involved.

After27 minutes

54Vessel speed
18kts

After
18 minutes

3 nauticalmiles

3 nautical
mles
miles

0-1
-----Give-way vessel* When another vessel is crossing safely ahead after turning 90˚ to starboard, turn to port to cross ahead of the other vessel. Continue with a full turn if anxious.
* The other vessel sometimes turns to starboard to avoid. Use VHF for communication up to 8 nautical miles (approx.), and request passing astern of your vessel.
* When 8 nautical miles (next approach in approximately 20 minutes) is reached, begin turn to port while holding turn rate to approximately 5˚/minute to ensure thatspeed does not drop.
* While watching movement of the other vessel, steer the vessel with the intention of turning until on a parallel course with the other vessel. If the other vesseltakes avoiding action, return to the original course while ensuring that it is not ahead of abeam.
* If the other vessel does not take avoiding action, measure distances ahead and astern, and to port, immediately the parallel course is reached (3.5 nautical miles
ahead and astern, 3 nautical miles to port).
* While maintaining a safe distance, return to the original course to cross ahead (cross 1.6 nautical miles ahead of other vessel)→ within reason.

Evaluate whether or not to make the turn at this point. Continue verifying compass direction.
* Steer the vessel while ensuring that the other vessel is not ahead of port abeam.
* 90˚ turn = 18 minutes (turn rate 5˚/minute) = speed 18kts, distance of travel 5.4 nautical miles, turn radius 2.9 nautical miles. Remember these values wh le on board.

Appendix ③− ３Navigator Education - Navigation Questions and Answers

Navigation for vessels crossing (answer)

Case２

Miles
7

Other vessel: 18kts

65

14 nautical miles
50˚ (approx.)
Bearing changed slightly tostarboard due to vessel crossing.
On this heading, the vessel willpass
in approximately 0.3 nautical miles(in approximately 36 minutes).
Vessel travelling at 18kts. Othervessel travelling at 15kts.
No other vessels involved.

2.7 nautical milsmiles

4
5.2 nautical miles

3

After 27 minutes
Almost port abeam
After 18 minutes
Approximately 48˚astern of port abeam

After 9 minutes
Approximately 5˚astern of port abeam

1

Vessel speed
15kts

4.0 nautical miles

7.8 nautical miles

2

After 36 minutes
Other vesselcloses to and passes
0.2 nautical miles oﬀ bow

0-1-2-6-----

Give-way vessel:
Turning to port to pass astern of the other vessel to port should be done only when intentions have been mutually veriﬁed
by VHF while at least 10 nautical miles is available.
Crossing ahead of the other vessel is not possible when turning to starboard. Turn provided if the other vessel does not takeavoiding action.
Do not begin a turn to port after turning to starboard to a course parallel to the other vessel (a collision course will result if
the other vessel turns to starboard).
Repeatedly request via horn, signal lamp, and VHF to encourage avoiding action by the other vessel.
When the speed of the other vessel is greater that your vessel, the ﬁrst assumption should be that turning to starboard
and passing ahead is not possible.
Since the other vessel sometimes turns to starboard suddenly, do not turn to port.