Sailed4seas的部落格

Ex 04-06

Ownship speed is 18.6 Knots and course is 063.8 degrees at beginning. ​

The situational awareness is:

• With three minutes vector length in 18.6 Knots, this vector is about 9 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 same speed as ownship. (skill by comparing vector length)
• Ownship have three crossing vessel at port side (yellow circle), distance unknown. (sighted)
• One overtaken vessel at port side slower than ownship. (skill by comparing vector length)

The situational awareness with 6 minutes speed vector is:

• One port side crossing vessel will be at ownship bow after three minutes. ( skill by observing target vessel speed vector touched our heading at three minutes (yellow square))
• One starboard side crossing vessel will be at ownship bow after 4 minutes. ( skill by observing target vessel speed vector touched our heading at 4 minutes)

The situational awareness with 9 minutes speed vector is:

• Ownship have one collision point with crossing vessel at starboard side (Red Square), after 7.5 minutes or so. (sighted)
• Another crossing starboard side vessel has no collision risk as 9 minutes speed vector has no collision point. (sighted)
• One crossing vessel at port side will be at ownship bow after 7.0 minutes or so (Pink Square). (sighted)

Overall situation awareness is:

• Ownship have to take care of three vessels around but no collision risk right now.(action)
• Ownship has to give way (avoid arriving red square area at same time with target vessel)  if starboard crossing vessel keeps current speed and course.(action)
• Does Port side crossing vessel keep his course after crossed separation line? (suspect)
• Forget other slower vessels, it is no harm can be done.(suspect)

After 02 minutes exercise time lapsed:

Ownship speed is 14.5 knots which decreased from 18.6 kts with engine output 15% from beginning.

Ownship course had altered 3 degrees starboard side to 066.4 degrees from 063.8 degrees with rudder cycle from “starboard 20”and “Port 20”over one minute.

The situational awareness is:

• Ownship reduced speed decisive with less engine output 15%. (sighted)
• Speed reduces 4 knots over two minute’s time. (sighted)
• Port side crossing vessel is about to pass ownship bow after 1.5 minutes (yellow circle). (skill by judging collision point on her speed vector)
• One overtaking vessel at starboard side is about to pass ownship bow after 1.5 minutes (yellow circle). (sighted.)
• Crossing vessel at starboard side will pass ownship bow after 4.5 minutes (red circle). (skill by estimating 6 minutes vector)
• One overtaken vessel at port side is still slower than ownship. (skill by comparing vector length)
• One crossing vessel at port side is about to pass ownship bow after 5 minutes (green circle). (skill by estimating 6 minutes speed vector direction)

After 03 minutes 30 seconds exercise time lapsed:

Ownship speed is 12.6 knots which decreased from 14.5, 18.6 kts with engine output 15% from beginning.

Ownship course had altered 1.5 degrees starboard side to 067.9 degrees from 066.4, 063.8 degrees with rudder cycle from “starboard 5”and “Port 5”over last minute.

The situational awareness is:

• Ownship reduced speed decisive with less engine output 15%. (sighted)
• Speed reduces 6 knots over 3.5 minute’s time. (sighted)
• The distance creates from last 3.5 minutes decisive engine output reduction is 1.8 cables. ( skill by calculation, do it by yourself)
• This extra distance keep ownship sail behind the collision point of other vessels. (statement)
• Other ship arrive the collision point is still the same time as the exercise begin. (statement)
• Only thing changed in this scenery is ownship about to arrive collision point later than anybody else. (sighted)
• Two vessels in Orange Square are passed. (sighted)
• Two vessels in yellow circle are about to pass after three minutes or later. (sighted)
• Once, the situations are so complicated. Now everything is cleared by sight of our own eye. (skill)
• The moral stands “ Less speed means less collision risk”. (rule) 

After 05 minutes 00 seconds exercise time lapsed:

Ownship speed is 11.0knots which decreased from 12.6, 14.5, 18.6 kts with engine output 15% from beginning and further reduce to 0% last minute.

Ownship course had altered 1.5 degrees starboard side to 069.5 degrees from 067.9, 066.4, 063.8 degrees with rudder order  “Port 20”over last 40 seconds.

The situational awareness is:

• Two vessels in Orange Square are passed. (sighted)
• Ownship reduced speed decisive with less engine output 15% from beginning and further reduced to 0%. (sighted)
• Speed reduces 7.6 knots over 5 minute’s time. (sighted)
• The distance creates from last 5 minutes decisive engine output reduction is about 3.16 cables. ( skill by calculation, 7.6/2 is average speed reduction, multiple 5 minutes run = 3.16 cable)
• This extra distance 3.16 cable keep ownship sail behind the collision point of other vessels. (statement)
• Other ship arrive the collision point is still the same time as the exercise begin. (statement)
• Only thing changed in this scenery is ownship about to arrive collision point later. (sighted)
• Cargo vessels NO. 21 in red circle is about to pass ownship bow after one minute. (sighted)
• Ownship is about to arrive this collision point 4 minutes later.(sighted)
• The time lapses compared with scenario in beginning is 3 minutes. (sighted)
• Tanker No.7 in yellow circle is about to arrive collision point after 3 minutes. (sighted)
• Ownship is about to arrive this collision point 8 minutes later.(sighted)
• The time lapses compared with scenario in beginning is 5 minutes. (sighted)
• Ownship had reduced same speed for both vessels, why the time lapsed is different? (suspect) 
• The moral is “ Speed reduction is more effective to avoid high speed vessel collision”. (rule) 
• New collision risk aroused. Where is it? (suspect)
• How can we detect it? (suspect)

Take a close look. What speed vector we are using now? (skill by experienced user)

After 06 minutes 29 seconds exercise time lapsed:

Ownship speed is 9.3 knots which decreased from 11.0, 12.6, 14.5, 18.6 kts with engine output 15% from beginning and further reduce to 0% from 2.5 minutes.

Ownship course had altered 1.3 degrees port side to 068.3degrees from 069.5, 067.9, 066.4, 063.8 degrees with rudder order  “Starboard 10”and “starboard 5”over last minute.

The situational awareness is:

• Two vessels in Orange Square are passed. (sighted)
• Speed reduces 1.7 knots over last 1.5 minute. (sighted)
• The distance creates from last 1.5 minutes decisive engine output reduction is about 2.12 cables. ( skill by calculation, 1.7/2 is average speed reduction, multiple 1.5 minutes run = 2.12 cable)
• This extra distance 2.12 cable keep ownship sail behind the collision point of other vessels. (statement)
• Other ship arrive the collision point is still the same time as 1.5 minutes before. (statement)
• Only thing changed in this scenery is ownship about to arrive collision point later. (sighted)
• Ownship speed reduction is effective in beginning.(sighted)
• Why ownship speed reduction is ineffective after we are in maneuvering speed? (suspect) 
• May be we forget the first rule “ Safe position is more effective than safe speed”. (rule especially for slow speed vessel) 
• Beware the starboard side overtaking vessel. (sighted)
• Where is collision point with crossing vessel right now? (suspect)
• How to do from now on? (suspect)
• Decisive rudder cycling might be help? (suspect)
• To which side first hard over rudder angle should be used? (suspect)