Sailed4seas的部落格

Ex 06-02

Ownship speed is 21.0 Knots and course is 065.3 degrees at beginning. 
The situational awareness is:
•    With three minutes vector length in 21.0 Knots, this vector is about 10 cables distance as above. (skill by knowing  three minutes run)
•    Ownship has three crossing vessels at starboard side, situation unknown. (sighted)
•     Three crossing vessels at starboard side, distance unknown. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• One overtaken vessel at port side has slower speed. (skill by comparing vector length)

By change speed vector length to 6 minutes, the situation awareness is

•   Two crossing vessels at starboard side have collision risk with ownship. (sighted)
•   Collision with green vector vessel first then red vector one. (sighted)

• Collision point is almost coincided. (sighted)
• One crossing vessels at starboard side have no collision risk with ownship. (one minute later)
  
• After 2 minutes 00 seconds exercise time lapsed:
  Ownship speed is 18.8 knots which decreased from 21.0 kts with engine output reduced from beginning and increased to 100%. 
  Ownship course had altered 5.3 degrees starboard side to 070.6 degrees from 065.3 degrees with starboard rudder ” in beginning and further starboard side turning. 
  The situational awareness in 3 minutes speed vector is:
  •    Ownship reduced speed is ineffective. (sighted)
  •    Speed reduces 2.2 knots over 2 minute’s time. (sighted with reducing rate of 1.1 knots per minutes)
  • Ownship speed vector is 9.4 cables long now. (known by 18.8 knots speed)
• Two crossing vessels at starboard side, distance unknown. (sighted)
• One crossing vessels at starboard side seems OK. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• One overtaken vessel at port side is about same speed. (skill by comparing vector length)

By change speed vector length to 6 minutes, the situation awareness is

•   One crossing vessels at starboard side (red circle) have collision risk with ownship after 4.5 minutes. (sighted)

• One crossing vessels at starboard side (yellow circle) will pass ownship bow after 4 minutes. (sighted)
• One crossing vessels at starboard side will pass ownship bow after 2 minutes. (sighted)
   

• After 2 minutes 30 seconds exercise time lapsed:
  Ownship speed is 20.3 knots which increased from 18.8, 21.0 kts with engine output increased to 100%. 
  Ownship course had altered 9.6 degrees starboard side to 080.2degrees from 070.6, 065.3 degrees with starboard rudder ” one minute. 
  The situational awareness in 3 minutes speed vector is:
  •    Ownship reduced speed is increased. (sighted against all rule)
  •    Speed increased 1.5 knots over 30 second time. (sighted with increasing rate of 3.0 knots per minutes)
  • Ownship speed vector is 10.2 cables long now. (known by 20.3 knots speed)
• Two crossing vessels at starboard side is still out of reach of 3 minutes speed vector. (sighted)
• One crossing vessels at starboard side will pass ownship bow after one minute. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• One overtaken vessel at port side is slower now. (skill by comparing vector length)

By change speed vector length to 6 minutes, the situation awareness is

•   One crossing vessels at starboard side (red circle) have collision risk with ownship after 4.0 minutes. (sighted)

• One crossing vessels at starboard side (yellow circle) will pass ownship bow after 1.5 minutes. (sighted)

What happened here?

• One crossing vessels at starboard side (red circle) have collision risk with ownship after 4.0 minutes. (sighted)
• This vessel had altered course to port side 9.6 degrees during last 30 seconds.( turning rate is 19.2 degrees per minute)
• Ownship and target vessel altered course at the same time during last 30 seconds. (sighted)
• Ownship collision points had shifted to boundary line of traffic lane. (sighted)
• Collision points are moving From yellow square to red square along target vessel speed vector. (sighted)
• Where ownship heading pointed is where collision risk will be. (Rule)

After 3 minutes 30 seconds exercise time lapsed:
Ownship speed is 22.9 knots which increased from 20.3, 18.8, 21.0 kts with engine output increased to 100%. 
Ownship course had altered 1.6 degrees starboard side to 081.8 degrees from 080.2, 070.6, 065.3 degrees. 
The situational awareness in 3 minutes speed vector is:
•    Ownship reduced speed is increased. (sighted against all rule)
•    Speed increased 2.6 knots over 60 second time. (sighted with increasing rate of 2.6 knots per minutes)

• Ownship speed vector is 11.4 cables long now. (known by 22.9 knots speed)

• Two crossing vessels at starboard side are inside the reach of 3 minutes speed vector. (sighted)
• Collision lines (3 minutes speed vector) are not crossed means no collision risk even in close range. (statement)
• One crossing vessels at starboard side had pass ownship bow. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• One overtaken vessel at port side is slower now. (skill by comparing vector length)

•   One crossing vessels at starboard side (red circle) continued her turn to port side. (sighted)

• What happen from now depends ownship attention on her turning now? (skill by knowing which one to look after)

• One crossing vessels at starboard side is at ownship bow now. (sighted)

After 4 minutes 30 seconds exercise time lapsed:
Ownship speed is 20.1 knots which decreased from 22.9, 20.3, 18.8, 21.0 kts with engine output decreased to 23%. 
Ownship course had altered 3.1 degrees port side to 078.7 degrees from 081.8, 080.2, 070.6, 065.3 degrees. 
The situational awareness in 3 minutes speed vector is:
•    Ownship reduced speed is effective. (sighted)
•    Speed decreased 2.8 knots over 60 second time. (sighted with decreasing rate of 2.8 knots per minutes)

• Ownship speed vector is 10.0 cables long now. (known by 20.1 knots speed)

• Two crossing vessels at starboard side are inside the reach of ownship 3 minutes speed vector. (sighted)
• These two crossing vessels had no collision risk as collision lines are not crossed. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• One overtaken vessel at port side is about same speed. (skill by comparing vector length)

•   One crossing vessels at starboard side kept her course steady. (sighted)

• What we can see now “Collision line had no crossing point means no collision risk ”? (statement)

After 5 minutes 30 seconds exercise time lapsed:
Ownship speed is 19.1 knots which decreased from 20.1, 22.9, 20.3, 18.8, 21.0 kts with engine output decreased to 23%. 
Ownship course had altered 5.9 degrees port side to 072.6 degrees from 078.7, 081.8, 080.2, 070.6, 065.3 degrees. 
The situational awareness in 3 minutes speed vector is:

• Those two crossing vessels had passed ownship bow. (sighted)
• One crossing vessel at port side had altered course to port side not entering the traffic lane. (sighted)

• One overtaken vessel at starboard side has slower speed. (skill by comparing vector length)
• This picture is showing “Collision line concept is Ok for close quarter situation like these”. (sighted)

End of Ex 06-02