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VLCS , a 14000 TEU vessel sailing under the Panama flag , was in collision with a Very Large Crude Carrier (VLCC) at approximately 23.55 (local time)

The container ship VLCS has overall length of 365.80 m, moulded beam of 52.00 m and maximum draft of 12.00 m. The vessel has deadweight of 165,908 DWT, gross tonnage of 153,115 GRT and capacity to carry 14,000 TEU. 

The VLCC VLCC (IMO: 9356593) had deadweight of 319,999 DWT and gross tonnage of 164,241 GRT. The ship was en route from Beilun, China to Port of Khark, Iran under ballast.  Length Overall x Breadth Extreme:  333 m x 55 m .  Draught 17.8 m / 21.1M.
At about 2355 hrs on 3^rd Aug 2016, Maritime and Port Authority of Singapore (MPA) was notified of a collision involving VLCC IIVLCC (Very Large Crude Carrier) and VLCS (Container Ship)  in the Singapore Strait, about 3 km South-East of Sebarok Island. Both are Panama-flagged vessels. 

VLCC II sustained damage to her bow whilst VLCS sustained damages on her port quarter hull. Both vessels are in stable condition and safely anchored in Singapore. VLCS reported that 10 empty containers fell overboard during the incident, 4 onto the deck of VLCC II and the rest into the water.

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Situation Awareness:

​Time 14:56:47

Speed vector are three minutes. Stand on vessel "VLCS" course 129 degrees / speed 7.4 Kts. Crossing vessel VLCC course 249 degrees speed 15.0 Kts. 

If Both vessels maintained her course and speed, Crossing vessel VLCC will pass collision point earlier (4 minutes later 15:00:47). Stand on vessel "VLCS" will pass collision point later (5 minutes later 15:01:47).

However, one minute time difference is barely enough. One minute distance are 15 Kts x 1 Minute = 463 Meters. VLCC is 333 meters long which will have the danger to be hit by VLCS at VLCC STERN.

The DTC (distance to collision) of VLCC is 4 minutes run x 15 Kts = 1 NM (1852 Meters) which are 5.6 Ship’s Length. VLCC still has the option to alter course to starboard side to clear CLCS.  

Time 14:57:47 (one minute passed)

​Stand on vessel "VLCS" course 132 degrees (from Port side 129) / speed 10.3 Kts ( increased very fast from 7.4).

Crossing vessel VLCC course 247 degrees (from 249) /  speed  14.3 Kts.( decreased slowly from 15.0)

If Both vessels maintained current course and speed, collision will happen about three and half minutes later. POC (Possible area of collision with two ship lengths in diameters) shows as a big yellow circle.

Possible collision ship hull is Bow to Bow, or VLCS Bow hit VLCC Midship section as VLCC arrives a little bit earlier.

VLCC should alter course to starboard side to prepare for bow to bow collision with “Hard Starboard Rudder” and “Crash stern telegraph on Main Engine). 

VLCS had increased speed in M/E”very quickly without alter course. This is an obvious mistake.

Time 14:58:17 (30 seconds passed)

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Stand on vessel "VLCS" course 134 degrees (from Port side 129) / speed 11.0 Kts (increased slowly from 10.3 ).

Crossing vessel VLCC course 248 degrees (from 249) /  speed  13.8 Kts.( decreased slowly from 14.3)

Both vessels course and speed change slowly during this 30 seconds, collision will happen about three minutes later as predicted. POC (Possible area of collision with two ship lengths in diameters) shows as a big yellow circle.

Possible collision ship hull is Bow to Bow, or VLCC Bow hit VLCS Midship section as VLCS arrives a little bit earlier (collision situation had changed from last 30 seconds). VLCS had got herself a nightmare to overcome in the three minutes to come.

VLCC should alter course to starboard side to prepare for bow to bow collision with “Hard Starboard Rudder” and “Crash Astern telegraph on Main Engine). 

VLCS should go “Crash Astern in M/E”, VLCS speed could increase very quickly from 7.4 to 11.0 Kts in 90 seconds (56:47 to 58:17). VLCS should be able to reduce very quickly at same time interval.

Time 14:58:47 (another 30 seconds passed) Most critical moment = Last chance to avoid

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Both vessels course no change, speed change slowly during this 30 seconds, collision will happen about 2.5 minutes later as 30 seconds had passed. POC (Possible area of collision with two ship lengths in diameters) shows as a red circle.

Stand on vessel "VLCS" course 134 degrees (No change) / speed 11.4 Kts (increased slowly from 11.0/10.3 ).

Crossing vessel VLCC course 249 degrees (No Change) /  speed  13.3 Kts.( decreased slowly from 13.8)

Possible collision ship hull:  VLCC Bow hit VLCS Midship section as VLCS arrives one minute earlier (collision situation had not changed from last 30 seconds). VLCS had got herself midship section open to collision.

VLCC should alter course to starboard side to prepare for bow to bow collision with “Hard Starboard Rudder “or rudder cycling and “Crash stern telegraph on Main Engine. 

VLCS should go “Full Ahead in M/E”to clear of POC, or prepare to alter course to Starboard side if situation is worse (VLCS cannot clear of VLCC bow collision with own ship’s midship section.

Now look at this pictures 14:58:47:

1. Original Crossing situation is not End to End which means "two vessel did not arrive at same time in collision point", THREE MINUTES speed vectors of both vessel is the clue. Before we know nothing about what will happen next, we know now VLCS will arrive earlier than VLCC.
2. Both vessel are big enough 330 meters at least, the VLCC is easier to turn, harder to stop and the VLCS is HARDER to turn, EASIER to stop. VLCC vessel’s track is twisting from the beginning which shows this VLCC is hard to maintain her course. VLCS vessel’s track is quite smoothie.
3. VLCC cannot stop turning even she saw VLCS had passed her bow area.
4. VLCS doing is great job in maneuvering her vessel to give clearing track to avoid the collision point both from own ship bow and stern with the pity to increase ship’s speed from 14:56:47 Hours from the beginning.
5. Collision could be avoided if VLCC applied “Hard Starboard” rudder at 14:59:37 Hours. It is clear VLCS will pass collision point one minute earlier than VLCC.
6. VLCC Left Turning is chasing VLCS. VLCC Right Turning is avoiding VLCS.
7. VLCS should keep original speed of 7.4 Kts to avoid Collision.
8. One minute distance for 12 Kts speed vessel is two cables which means One ship’s Length for VLCS( 370 meters). Two vessels ETA POC Possible area of Collision is one minute difference which means VLCS arrive earlier will have danger collision point at VLCS ship’s stern.
9. Does Two minutes enough for a 90 degrees turning to starboard side? The answer is YES. Check your own ship maneuvering curves on bridge.
10. Rudder Cycling may be recommended to use at 14:58:47 for VLCC.
11. Hard Starboard Rudder is recommended at 14:59:37 for VLCC.

Time 14:59:37 (another 50 seconds passed from 14:58:47)

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Stand on vessel "VLCS" course 140 degrees (from Port side 134) / speed 11.9 Kts ( increased slowly from 11.4 ).

Crossing vessel VLCC course 247 degrees (from 249) / Speed  12.7 Kts.( decreased slowly from 13.3)

Both vessels course and speed change slowly during this 50 seconds, VLCS is already inside the POC (Possible area of Collision) what she need now is two minutes time for her to clear this POC .  POC (Possible area of collision with two ship lengths in diameters) shows as a Yellow circle.

Possible collision of ship hull: VLCC Bow hit VLCS stern section as VLCS arrives one minute earlier (collision situation had not changed from last 80 seconds). VLCS had got herself midship section open to collision.

VLCC should

1. verify the Relative Bearing of VLCS bow decreasing quickly and (VLCS BOW is cleared)
2. Relative Bearing of VLCS stern almost no change (VLCS stern is not clear) in this 50 seconds
3. to see VLCS have the chance to clear own ship’s bow and prepare to alter course to starboard with “Hard Starboard Rudder “ to clear the VLCS stern and “Crash stern telegraph on Main Engine. 

VLCS should verify the Relative Bearing change of VLCC at Port bow and go “Full Ahead in M/E”to clear POC, prepare to use “Hard Port Rudder “ to kick own ship stern hull off if VLCC’s bow passed own ship Pivot Point with collision risk.

Time 14:59:47 (another 60 seconds passed from 14:58:47)

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Stand on vessel "VLCS" course 142 degrees (from Port side 134) is turning to Starboard Side / speed 11.9 Kts ( increased slowly from 11.4 ).

Crossing vessel VLCC course 246 degrees had no change (from 249) / only Speed 12.4 Kts.( decreased slowly from 13.3)

Both vessels course and speed change slowly during this 60 seconds, VLCS is already inside the POC (Possible area of Collision) what she need now is two minutes time for her to clear POC.  Red circle is Original Collision Point .

Possible collision of ship hull: VLCC Bow hit VLCS stern section as VLCS arrives one minute earlier (collision situation had not changed from last 90 seconds). VLCS had got herself midship section open to collision.

VLCC should

4. verify the Relative Bearing of VLCS bow decreasing quickly and (VLCS BOW is cleared)
5. Relative Bearing of VLCS stern almost no change (VLCS stern is not clear) in this 60 seconds
6. to see VLCS have the chance to clear own ship’s bow and prepare to alter course to starboard with “Hard Starboard Rudder “ to clear the VLCS stern and “Crash stern telegraph on Main Engine. 

VLCS should verify the Relative Bearing change of VLCC at Port bow and go “Full Ahead in M/E”to clear POC, prepare to use “Hard Port Rudder “ to kick own ship stern hull off if VLCC’s bow passed own ship Pivot Point with collision risk.

Time 15:00:17 (another 90 seconds passed from 14:58:47) 

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Stand on vessel "VLCS" course 151 degrees (from Port side 134) is turning 17 degrees to Starboard Side / speed 11.7 Kts ( increased slowly from 11.4 ).

Crossing vessel VLCC course 242 degrees had changed 7 degrees to Port side (from 249) / only Speed 12.0 Kts.( decreased slowly from 13.3)

Both vessels course and speed had changed slowly during this 90 seconds, VLCS’s Bow already clear collision point and stern hull still inside POC (Possible area of Collision) what she need now is decide “How her stern Can clear VLCC’s bow?”.  Red circle is Original Collision Point and should be the point VLCC’s bow will hit VLCS stern.

Possible collision of ship hull: VLCC Bow hit VLCS stern section as VLCS bow passed collision point and stern was not. VLCS had got herself midship section open to collision.

VLCC should

7. verify the Relative Bearing of VLCS bow decreasing quickly and (VLCS BOW is cleared own ship)
8. Relative Bearing of VLCS stern almost no change (VLCS stern is not clear) in this 90 seconds
9. to see VLCS have the chance to clear own ship’s bow and prepare to alter course to starboard with “Hard Starboard Rudder “ to clear the VLCS stern and “Crash stern telegraph on Main Engine. 

VLCS should verify the Relative Bearing change of VLCC at Port bow had changed to Port Beam. Have the choice to go “Full Ahead in M/E”to clear POC, prepare to use “Hard Port Rudder “ to kick own ship stern hull off if VLCC’s bow passed own ship Pivot Point with collision risk.

Time 15:01:17 (another 2.5 minutes passed from 14:58:47) Possible Collision Time 

Stand on vessel "VLCS" course 149 degrees (another turn to Port side breaking point) / speed 11.3 Kts (increased to 11.9 then decreased slowly from 11.4 ).

Crossing vessel VLCC course 225 degrees had changed 24 degrees to Port side (from 249) / only Speed 11.4 Kts.( decreased slowly from 13.3)

1. Red circle is Original Collision Point and should be the point VLCC’s bow will hit VLCS stern in the beginning.
2. Yellow circle is possible collision point which had shifted 100 meters more by VLCS double breaking turning.
3. There is no reason at all for VLCS to reduce engine.
4. VLCC is chasing the tail of VLCS. It is a bad day for VLCS.
5. If no collision happened, no one will blame VLCS for increased speed from 7.4 Kts to 11.9 Kts into a Traffic Separation Scheme.
6. Why VLCC don’t want to alter course to Starboard from the beginning when
   • there is no collision risk at 14:56:47 = No need to change course
   • there is collision risk at 14:57:47 = Maybe VLCS realize the risk will slow down her speed or VLCC did not notice stand one vessel VLCS increase speed fro, 7.4 kts to 10.3 Kts
7. At 14:58:17, collision risk is rigid, collision will happen in three minutes time from 14:58:17 and POC (possible area of Collision is two ship’s length = two minutes distance run.
8. Best action to aid collision avoidance will need to observe the Relative Bearing change of Other vessel’s BOW and STERN increased or decreased.
9. Both vessels turning to Port may be the interaction of ship’s hull during the Scratch Collision.

  Time 15:01:37 (20 seconds passed collision)

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Stand on vessel "VLCS" course 136 degrees (from 149 degrees) / speed 7.0 Kts (may be stopped due to collision, reduced from 11.0 Kts ).

Crossing vessel VLCC course 172 degrees had changed 53 degrees to Port side (from 225) / Speed 10.0 Kts.( decreased from 11.4 Kts)

Three minutes from 14: 58:47, VLCC arrived original collision point and VLCS was not there. If VLCC had kept Original course, it would have a happy ending. The fact is VLCC arrived breaking point here (may be put Port  rudder two minutes before now at 14:59:37 or course change due to collision). Turning rate 130 degrees per minutes is way too much which imply the rudder she used is "Hard Port"). What happened next is beyond human control. 

Time 15:02:57 (100 seconds passed collision)

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Stand on vessel "VLCS" course 113 degrees (from 136 degrees) / speed 2.1 Kts (reduced from 7.0 Kts ).

Crossing vessel VLCC course 130 degrees had changed 42 degrees to Port side (from 172) / Speed 4.8 Kts.( decreased from 4.8 Kts)

Time 15:03:27 (130 seconds passed collision)

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x  The accident was reported in 2355 Hours. What is the actual collision time?

 it happened in this time 15:03:27 (GMT), local time 23:03:27. Both vessels had altered course of 90 degrees from original course.  VLCS vessel had only 1.5 Kts at collision and VLCC had

Time 15:04:47 (3.5 minutes passed collision): Possible collision again, VLCS increase speed to avoid.

 Time 15:07:37 (6.3 minutes passed collision): ​