Collision avoidance at night

[Martkimwat]

Originally Posted by dokondr

You final thought: "Going back to your scenario showing the boats as close as they are, both watch keepers would have to be asleep to get into that level of proximity before action was taken" is quite possible in real world, I think. One skipper for sure may be asleep and on autopilot.


So I would suggest the following end-to-end solution:


But first, great effort to solve this, thanks everybody! Many interesting ideas and some of them very close to the right solution :-)
So the question:
- 1.1. You are close-hauled on port tack at night. On your port bow, on a steady bearing, is a green light. What do you do?





And now the correct answer:
- Tack. Another yacht could be on either tack. You should assume it is on a starboard and take avoiding action.

There is no steaming light visible, therefore vessel is under sail. When two vessels under sail cross, the stand on vessel is the one on a starboard tack, IRPCS Rule 12(a)(i).

And the Rule about which this question is all about is 12(a)(iii):

(iii). if a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether the other vessel has the wind on the port or on the starboard side, she shall keep out of the way of the other.

A quick tack is the right action to take -- no time for VHF or searchlights. The Rules are clear about what to do. After we finish the tack another boat should see our green light and will rightly continue on the previous course as a stand-on vessel.

Have a look at the attached drawings: A - our boat, B - another boat. Tack is the right action but nevertheless we need be careful doing it! It may happen so another boat B will see our red light a second before we start the tack and will, according to the rules change course and we will be on the collision course. So we can still have a collision if we do it wrong. To avoid collision, after the tack A should be on a beam reach not close-hauled. Tacking to close-hauled course is dangerous!

Just one more point here, if boat B is already on starboard, as in your diagram, he will see your solitary red light and know you are a sailing vessel, he should also be aware that you cannot be on starboard tack showing that aspect of your boat to him, therefore he should realise he is the stand on vessel and give you a chance to tack as per rule 12. Only if he is on port tack might he have some doubt and try to take avoiding action first, but that will take time as he must first gybe which will require him to pull the main onto the centreline, whilst bearing away onto a run, let out the main, and only then round up on starboard. you, meanwhile will have tacked relatively quickly. Bearing in mind that he was fine on your port bow, on a constant bearing, it is most unlikely he would be anywhere near colliding with you in this second scenario, but nonetheless you will now have him in clear unimpeded view off your starboard quarter, ready for you to bear away further if needs be.(note if he crash gybed and didn't bring his rig down, he would have taken most of the way off his boat and would be sitting with his head to windward, sails flapping)

[Wotname]

Gosh, I go for a snooze and another dozen long posts get added to the thread

Originally Posted by Dockhead

I don't say that tacking is "so much better". I am not dissing falling off at all, and I don't think anyone here is wrong. I hear all the reasons put forward by you and others for falling off -- in my opinion they are not wrong.

That is correct, you did not say tacking is "so much better". I inferred that from your statements This is why I like the tack vs. falling off after which some supportive arguments were made and you finished with These are powerful arguments. I was wearing the devil's hat at time and you must expect the devil to be conniving and deceitful .


Only quibble I have with what you wrote is about the "immediate indication of safety". I contend that when you see his green (and no red) at least 3 or 4 points off your starboard bow, that you know that a collision is impossible, and you need no other data, not bearings, or anything, to know that.

Not even the devil can dispute this!


That is the crucial advantage of the tack, in my opinion. In less than a minute, maybe less than half a minute -- and the timing may be crucial if you are close -- you can be sure. You can't even take a proper series of bearings in the amount of time you can achieve that with the tack.


How one FEELS about this might be much influenced by the boat. With a boat which is very cumbersome to tack and which loses way and is at risk of getting into irons -- you might be less attracted to this than I am. My boat is really easy to tack -- although she is cutter rigged, the staysail is self-tacking, and with slippery dyneema taffetta on both sides of my jib, and I can pull the jib across in seconds. Showing the other side light in seconds.

And also influenced (wrongly) by position on your next waypoint. If beating to windward or if already laying your course line close hauled.

And still advocating for the . Why not hove to on a STBD tack and wait for the other vessel to pass?

FWIW, Wottie can see problems with this approach but would like to hear the arguments other posters can put forward.

[StuM]

Originally Posted by Wotname

And still advocating for the . Why not hove heave to on a STBD tack and wait for the other vessel to pass?

FIFY

[conachair]

Originally Posted by Wotname

And still advocating for the . Why not hove to on a STBD tack and wait for the other vessel to pass?

Seems a sensible option to an exam question, heaving to is a very useful if underused tool in the sailing box. Make a quick cuppa while you're at it .
though might need to be a little careful in the real world, some people either don't know the irpcs or think they know better and make up their own rules as they go along..

[Wotname]

^^ Thanks StuM ; the devil made me do it

Note to self, don't post before coffee!

[El Pinguino]

Originally Posted by Wotname

^^ Thanks StuM ; the devil made me do it

Note to self, don't post before coffee!

You have a morning nap?... now that is a worry......

I would hate to be on watch with any of you lot..... a very simple exam question and 5 days and 120 posts later .......

In orals you would have 10 seconds to answer the question... or cop another 6 months sea time....

I'm just waiting for someone to trot out Cockcroft... although something akin to Godwin's Law applies when that happens...

[El Pinguino]

Originally Posted by Wotname

Gosh, I go for a snooze and another dozen long posts get added to the thread






And still advocating for the . Why not hove to on a STBD tack and wait for the other vessel to pass?

FWIW, Wottie can see problems with this approach but would like to hear the arguments other posters can put forward.

If for whatever reason you choose not to tack just take the way off your boat... bring her up a bit further into the wind and dump wind from jib and main.... not really hove to but your boat should stop... just hope you don't end up in irons..

Easing your sheets and coming off the wind will see you trying to pass ahead of her... never a really clever idea... esp when not entirely sure of her heading...

And if she is heading east - as she could be in sketch below - it could be a very long drawn out business that will take you a long way out of your way......

[Wotname]

Originally Posted by El Pinguino

You have a morning nap?... now that is a worry......

I would hate to be on watch with any of you lot..... a very simple exam question and 5 days and 120 posts later .......

In orals you would have 10 seconds to answer the question... or cop another 6 months sea time....

I'm just waiting for someone to trot out Cockcroft... although something akin to Godwin's Law applies when that happens...

Crikey El Ping, you drive a hard ship. The alarm raised me from my nightly slumbers at 10am, by the time I heard the 10 o'clock news and had a scratch, I posted at 10.24....

As for the orals, the answer would be oh so simple and take all of 3 seconds.

Examiner : What is the correct action to take when bah bah?
Me: Tack sir!
Examiner: Why?
Me: 'cause current tack ain't working out too well and if in doubt, go about, sir!

Time for me afternoon nap now...

[Dockhead]

Originally Posted by El Pinguino

You have a morning nap?... now that is a worry......

I would hate to be on watch with any of you lot..... a very simple exam question and 5 days and 120 posts later .......

In orals you would have 10 seconds to answer the question... or cop another 6 months sea time....

I'm just waiting for someone to trot out Cockcroft... although something akin to Godwin's Law applies when that happens...

Oh, come on. We all go the exam question in seconds. We've all read Rule 12 and knew what they were getting at.


We went way beyond that into how to deal with that kind of crossing, and it's really interesting.



Don't be such a wet blanket! If it was such a stupid discussion, then why have you continued hanging out?

[El Pinguino]

Wot? I waited for 92 posts to see some one work out 'how's she heading' and apply some logic to the question.... then went back to my usual cowherding and stuff.... only came back when Wotsisname said he had morning naps.... which is still a worry and not fully explained...

Anybody seen the OP lately ??

[Wotname]

Originally Posted by El Pinguino

.... only came back when Wotsisname said he had morning naps.... which is still a worry and not fully explained...

Anybody seen the OP lately ??

Struth El P, it's only you calling me sleeping habits a morning nap. I call it a good nights rest. Wot more explanation is needed .

Toddle off to the sack after an evening of keyboard bashing whenever the eyelids get heavy, pump out the zed's 'till the alarm jangles (10am), have a scratch 'n carpe diem. And so on and so forth.

Jeezes Lucy, do ya need a hug in lockdown!


Oh, almost forgot , and


EDIT: the OP is napping now

[El Pinguino]

'pologies... bin a bit of a rum few days here... wet as I don't know what and windy enough to blow a dog orf its chain.. too much couch time hereabouts... I dream of cabin fever and long for the good old days up the Rio Pongo with nothing to worry about but dengue, yellow jack and malaria...

Back on track ..
Its an RYA question ... so Solent based... so in the OP's question lets say you are off Cowes bound eastish ... the green is heading for Wooton Creek... you bear away... and end up in Osborne House without a paddle and a bit of explaining to do....

tack..

[Wotname]

Originally Posted by El Pinguino

'pologies... bin a bit of a rum few days here... wet as I don't know what and windy enough to blow a dog orf its chain.. too much couch time hereabouts... I dream of cabin fever and long for the good old days up the Rio Pongo with nothing to worry about but dengue, yellow jack and malaria...
...........

No 'pologies needed - it's fake outrage...

[Lodesman]

Originally Posted by El Pinguino

Easing your sheets and coming off the wind will see you trying to pass ahead of her... never a really clever idea... esp when not entirely sure of her heading...

Oh come now. If it was daytime and the other vessel was on port, then she would very likely fall off to "take your stern" - would it horrify you to be passing ahead of her then?

[lars]

Odd we do have priviledged and burdened vessels where i come from. Right of way is terminology used to describe this more often than not. Everyone here kows there is no right of way. Just like bouys and strutures dont have port or starboard sides and there is no right or wrong side of marked channels..j