Sailed4seas的部落格

1. Own Ship original speed is 19.2 knots.
2. Own Ship original course is 066 degree as shown above.

Let's look at the first part: safe speed.

Vessel arrive the precautionary area with only 11.8 knots. This means that Own Ship has reduced almost half speed, 19.2 to 11.8 Knots. (Sighted) 

All Crossing traffics (crossing vessels) are not clear yet.  (sighted) 

 Ownship collision line(three minutes speed vector line) intersect with "Mobil No.1"   in 2 minutes run.   (sighted) 

"Mobil No.1"    already altered course to 066 degrees.  (sighted) 

"Mobil No.1"   speed is slower than Ownship.  (skill by compare the length of speed vector of ownship and target, not in the data area,  but  by eye estimation or with our  finger  span   or  like me,  you can use a divider  to compare on the monitor.)

If you have the habit to remember the Target Vessel speed, in this case "Mobil No.1"   is 10 knots speed.  Ownship is 1.8 knots faster than her. (sighted) 

Ownship collision risk with “Mobil No.1” is  20 minutes  later.  (  2 minutes run of  11.8 knots is 0.4 cable. 0.4 cable  for  1.8  knot run  is   20 minutes  )  
Other crossing vessels are faster than ownship by comparing. (skill by compare the length of speed vector of ownship and target, not in the data area,  but  by eye estimation or with our  finger  span   or  like me,  you can keep a divider beside the monitor for this purpose.)

Other crossing vessels are safe as long as ownship slower than them.  (statement)

Ownship further alter course to 060, 6 degrees to portside to give wide sea room for "Mobil No.1".  (suspect : this is the trouble) 

We can check the speed change in the diagram.

• Propeller revolution is in green color which had reduced twice in beginning and second minutes for safe speed.   (sighted)
• Rudder order is in light blue color. Ownship had applied Port rudder at 3-4 minutes time and steady at 5.5 minutes. (suspect) Course change is 6 degrees to port side. (sighted)

• Speed is in yellow color. Ownship continue to decrease.  (sighted)
• Heading is in red color. 

Ownship speed decreased slowly to 11.8 knot which postpone the collision risk with "Mobil No. 1 "  20 minutes later.   (sighted)

Let's look at the second part: safe position.

Ownship is nowhere to call in a safe position, must to proceed with caution as they always said.