Sailed4seas的部落格

Ex 05-03

Ownship speed is 20.0 Knots and course is 245.4 degrees at beginning. 
The situational awareness is:
•    With three minutes vector length in 20.0 Knots, this vector is about 10 cables distance as above. (skill by knowing  three minutes run)
•    Ownship have two crossing vessel at starboard side (red circle), distance unknown. (sighted)
•    One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
•    Ownship have one crossing vessel at port side (green circle), distance unknown. (sighted)
•    Two overtaken vessels at port side slower than ownship. (skill by comparing vector length)
 
The situational awareness with 6 minutes speed vector is:
•    There are 6 vessels inside the collision square (Orange square). (sighted)
•    There is no time to remember what vessel is ahead or behind, what vessel is on starboard side or port side? (suspect)
•    Ownship now knows that “It is Collision area to be avoided, not the vessels”(statement) 
•    Where to go for ownship? (suspect)
•    To starboard side, One port side crossing vessel (green circle) will be at ownship starboard bow after 6 minutes which block ownship way to starboard side. ( sighted) 
•    To port side, two starboard side crossing vessel (red circle) will be at ownship bow after 6 minutes which will block ownship way to port side. ( sighted)
•    To make a 360 degrees turn, many vessels inside the traffic lane. (sighted) 
•    Ownship has the option to reduce speed as fast as possible to arrive collision square later. (suspect)
 
After 03 minutes exercise time lapsed:
Ownship speed is 15.3 knots which decreased from 20.0 kts with engine output reduced to 55% from beginning. 
Ownship course had altered 1 degrees port side to 244.4 degrees from 245.4 degrees with rudder “Port 10 “in last 30 seconds. 
The situational awareness in 3 minutes speed vector is:
•    Ownship reduced speed once with less engine output 55%. (sighted)
•    Speed reduces 4.6 knots over 3 minute’s time. (sighted with reducing rate of 1.5 knots per minutes)
•    Overall situation looks good in this three minutes speed vector. (sighted)

• All crossing vessels are about to pass after three minutes.  (sighted)
• One overtaking vessel is at starboard quarter faster than ownship. (skill by comparison)
• Port side overtaken vessel ahead of ownship is OK now. (skill by comparing speed vector length)

After 04 minutes exercise time lapsed:
Ownship speed is 15.0 knots which decreased from 15.3, 20.0 kts with engine output reduced to 55% from beginning. 
Ownship course had altered 1 degrees starboard side to 245.7 degrees from 244.4, 245.4 degrees with rudder “Port 10 “in 30 seconds and “Hard Starboard “in last 40 seconds. 
The situational awareness in 3 minutes speed vector is:
•    Ownship reduced speed with less engine output 55% is slower now. (sighted)
•    Speed reduces 0.3 knots over last minute. (sighted with reducing rate of 1.5 knots per minutes in first 3 minutes)
•    Overall situation looks good in this three minutes speed vector. (sighted)

• One crossing vessels at starboard side is about ownship bow after three minutes (red circle).  (sighted)
• One overtaking vessel at starboard quarter is faster than ownship. (skill by comparison)
• Port side overtaken vessel ahead of ownship is OK now. (skill by comparing speed vector length)

After 06 minutes exercise time lapsed:
Ownship speed is 13.6 knots which decreased from 15.0, 15.3, 20.0 kts with engine output reduced to 55% from beginning. 
Ownship course had altered 5 degrees port side to 240.8 degrees from 245.7, 244.4, 245.4 degrees with rudder “Port 20 “in one minute and “Hard Starboard “in last 20 seconds. 
The situational awareness in 3 minutes speed vector is:
•    Ownship reduced speed with less engine output 55% is slower now. (sighted)
•    Speed reduces 1.4 knots over last minute. (sighted with rudder cycling effect)
•    Overall situation looks good in this three minutes speed vector. (sighted)

• One crossing vessels at starboard side is to pass after 1 minute.  (sighted)
• One overtaking vessel at starboard quarter is faster than ownship. (skill by comparison)
• Port side overtaken vessel ahead of ownship is OK now. (skill by comparing speed vector length)

After 07 minutes exercise time lapsed:
 

The situational awareness in 3 minutes speed vector is:
•        Speed is 13.9 knots over last minute. (sighted)
•    Overall situation looks good in this three minutes speed vector. (sighted)

• One crossing vessels at starboard side passed ownship bow.  (sighted)
• One overtaking vessel at starboard quarter is faster than ownship. (skill by comparison)
• Port side overtaken vessel ahead of ownship is OK now. (skill by comparing speed vector length)
• Two crossing vessels are at very close range. (sighted)

After 09 minutes exercise time lapsed:
Ownship speed is about 13.6 knots in last 4 minutes with engine output reduced to 51%. 
Ownship course had altered 7 degrees port side to 243.5 degrees from 250.5, 240.8, 245.7, 244.4, 245.4 degrees with rudder “Port 20 “  and steady again. 
The situational awareness in 3 minutes speed vector is:
•    Ownship just made it by controlling ownship heading in last minute. (sighted)
•   All course change is within 5 degrees heading changes. The consequence is huge after three minute run.

The moral of this exercise is “ Carefully change your heading, boldly reduce engine output”.

The reason why is“Course change can be effective within one minute, but speed reduction has 1.5 knots per minute effect only”.

One minute speed reduction (1.5 knots per minute) can create 23 meters difference in collision point.

End of Ex 05-03