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Old 12-08-2008, 00:05   #1
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Challenge: Collision Avoidance!

Ok, this Challenge thread will test us on Collision Avoidance decisions; “Assuming” only the information that is given by the OP. All the Collreg rules apply and unless stated we are following International Rules.

First scenario:
You are the skipper on a summer delivery trip from Hawaii to Vancouver BC on board a beautiful 82 ft Swan.

Upon entering Juan de Fuca Strait at night, patchy FOG closes in around you, but with good radar equipment and communication with “Victoria Traffic Management you are comfortably proceeding at 10 knots in the Inbound lane.

“Traffic” has confirmed the following around you.

There is a Salmon opening so the fleet is working along both inshore lines as well as in the Traffic Separation Zone.

P-1 is an outbound very large container ship you read about, making its maiden Voyage from Seattle. (Speed 22 knots)

OT-1 (12knts) and OT-2(15knts) are both Overtaking freighters with foreign captains and Traffic has informed them of your boat’s name and position.

Suddenly you notice on your ARPA (Radar) that P-1’s relative Plot has changed and is now on a collision course with you.

You confirm and then call with no reply….. Victoria Traffic then tries repeatedly to contact the Ship and finally gets an excited Master who comes on to explain that they have had both a mechanical steering failure and an electronic telegraph failure. The engineer is trying to shut down the main engine manually, emergency steering is stuck!

See Diagram

Plotting Data: CPA (closest point of approach) TCPA (Time for CPA)

You are OS (own ship) speed 10knts
P-1…….CPA….Collision……TCPA…….12 minutes
OT-1….CPA ….0.10nm…….TCPA…….7 minutes
OT-2….CPA…..0.15nm……TCPA……..6 minutes

WHAT WOULD YOU DO?
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Old 12-08-2008, 01:12   #2
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I would hold a steady course but slow down and let the 2 freighters overtake me as quickly as possible. And then get out of the way of the runaway container ship.
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Old 12-08-2008, 02:15   #3
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Can you be more specific in what direction you would take?
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Old 12-08-2008, 06:38   #4
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What's the top speed in a Swan 82? - If possible speed up and advise OT1 and OT2. Otherwise wait until they pass you then alter boldly to starboard to open the CPA, turning back before you enter the fishing fleet.
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Old 12-08-2008, 06:56   #5
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Top Speed 14 knots under power. Also their is a flood current going with you
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Old 12-08-2008, 07:44   #6
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don't understand why do u state that OTs are in collision course with you; pic shows that both OTs are overtaking you; and i doubt that Traffic Management would let OT-2 to overtake OS on Os's starboard side; i would stop the engines, maintain heading and blow the horn 5x short let both OTs and the fishing fleet to overtake me and probably steer on opposite line and change my heading for 180°
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Old 12-08-2008, 07:50   #7
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OT-2 is .5 mile behind. If you stop and OT-2 holds speed they pass in 2 minutes. At the same time your closing speed with P-1 is reduced. You have to get bearing change on P-1.

I am with lodesman.

Slow down to steerage speed in the current. Turn to starboard upon OT-2 passing. Head for the edge of the fairway and assess the bearing.

You now are left with two options to change bearing. Floor it or bear away outside the zone and deal with dodging fishing boats.
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Old 12-08-2008, 08:02   #8
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OK - the way I see it, OT-1 is also on a collision course with P-1, and his best escape is to alter to stbd, except for the fact that I'm in his way. If I come up to 14 kts and advise everyone concerned then he can alter to stbd behind me, and my CPA with P-1 should open to a shade under 0.8nm. OT-2 shouldn't really have a concern with P-1, and will continue to overtake me albeit at a slower pace - if I maintain my heading it shouldn't affect him.
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Old 12-08-2008, 08:03   #9
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I'd go with Ex-Calif. It'd be nice to put 120,000 tons of steel between me and the rogue ship. Just remember, once you go to flank with the Flood, your closing speed is up to 38 knots depending on whether he maintains speed or not and assuming a 2 knot Flood. While you can change the bearing quickly at that rate, ya also close the distance rapidly.
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Old 12-08-2008, 08:11   #10
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The current is a red herring, but could you advise on the actual visibility, I've been assuming in patchy fog you don't see P-1 about 6.4 nm ahead of you, but can see OT-1 about 0.2nm astern of you and probably see OT-2 at about 0.5nm?

Dan's solution is good too, but I'd be concerned about being a sitting duck and not knowing what OT-1 is going to do.


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Old 12-08-2008, 08:14   #11
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Quote:
Originally Posted by Lodesman View Post
The current is a red herring, but could you advise on the actual visibility, I've been assuming in patchy fog you don't see P-1 about 6.4 nm ahead of you, but can see OT-1 about 0.2nm astern of you and probably see OT-2 at about 0.5nm?
it's an arpa radar, visibility doesn't matter
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Old 12-08-2008, 08:15   #12
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Quote:
Originally Posted by Pelagic View Post
......“Assuming” only the information that is given by the OP. All the Collreg rules apply and unless stated we are following International Rules.

First scenario:
You are the skipper on a summer delivery trip from Hawaii to Vancouver BC on board a beautiful 82 ft Swan.

Upon entering Juan de Fuca Strait at night, patchy FOG closes in around you, but with good radar equipment and communication with “Victoria Traffic Management you are comfortably proceeding at 10 knots in the Inbound lane.

......
?
Quote:
Originally Posted by Lodesman View Post
What's the top speed in a Swan 82? - .
Quote:
Originally Posted by Pelagic View Post
Top Speed 14 knots under power. Also their is a flood current going with you
OK Pelagic, I am a bit confused here. I was trying to work only with the information given by the OP. I also was looking at the OS best speed. Given it's length is 82 ft (LOA, LOD, LWL - whatever), the absolute best hull speed I could calulate was 13.5 Kts but more likely 12 kts using "standard" formulas and interepation of its LWL. Now you add additional data stating 14 Kts.
So I would speed up to 14 kts keeping you well ahead of OT1 and increasing the TCPA for OT2 by a considerable amount. In therory the 40% increase in speed will remove you from the collision course with P1.

While you can't predict acturately the final movements of P1 because of its emergency situation, you can expect it will not increase in speed but might slow down increasing the potential safe distance between both of you. As soon as the situation becomes clearer, you MIGHT be able turn to port behind the fishing fleet in the seperation zone and also behind P1 and slow down heading the way you came but now in the outbound lane. You won't be hampered by OT1 because you are travelling 3 kts faster and you won't hamper OT2 because you are tuning away from him.

Once P1's condition and position is stablised, turn around again, change lanes, come home and have a well earned beer.
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Old 12-08-2008, 08:20   #13
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Slow to bare steerage and let the ships pass to each side. Then full speed bearing starboard to get just behind and to starboard of OT2. Let OT2 block. Stay near enough to OT2 to not get too close to the fishing fleet. If a close quarters situation developed with the fishing fleet, just drop behind OT2.
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Old 12-08-2008, 08:22   #14
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+ the container ship would probably take measures to stop for example dropping stern anchors; using bow thrusters or it that broken too? ()
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Old 12-08-2008, 08:50   #15
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If P1 is pointed dead at you already, going to flank will move you out of the way before he reaches you.
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