Collision Avoidance, Cones of Uncertainty, and Appropriate CPA

[conachair]

Originally Posted by ramblinrod

In this very section the rules do specifically identify some combinations that are and are not permitted, and do not specifically prohibit a masthead (located) tricolour and near deck sidelights and stern light being shown simultaneously..

It is explicitly prohibited. Rule 20B.

(b) The rules concerning lights shall be complied with from sunset to sunrise, and during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out.

Red over red with a port side tricolour / deck light can ,without a shred of doubt, be mistaken as NUC.

Top tip, if your opinion is outnumbered google-1, when virtually every link google comes up with says different as you spend some time reserching, might be time to consider you are maybe in error...

[evm1024]

This topic comes up often (tricolor and deck level navigation lights).

Looking over some of the other posts on this I came across this:

Assume the tug is overtaking. With your deck nav lights on he sees only your stern light. Seeing only a white light he's not yet sure what he's facing, but could be a stern light and he's overtaking, so he's particularily careful as he approaches the white light. You then turn on your mast head. Now he sees two white lights, one over the other. Ah ha, he says to himself - what I'm seeing is a big boat a long way away. I can see his range lights, but can't yet see his red/green nav lights. No need to slow down just yet. He sticks his head in his radar looking for the big contact with the hull down several miles distant and he doesn't see you, a small sailboat, because you don't show up very well and he's not looking for something just ahead of him because the reasonable conclusion from the lights presented is not a small boat dead ahead. Bang.

Here we clearly see a case where being laxadidlycal is not only confusing but could lead to a collision. And liability will fall on those who do not display correct lights in a greater proportion than those who do show correct lights.

In my experience sailors (3 or 4 that I have talked to) who display a tricolor and sidelights-stern light have minimal knowledge and experience. Or they just don't give a SH*T.

[transmitterdan]

If a manufacturer or repairman wires tricolor and deck level sidelights to a single switch this would be a serious matter in any resulting collision investigation. It is not just a matter of someone's opinion that they can't see the harm in it. It's clearly laid out in the plain language of the rules not to run two sets of running lights. It is confusing and not permitted.

I see quite a lot of inexperienced sailors running both lights. It is not ok and it is not just a pedantic rule thumper issue to say so. Anyone who is offended by some rule instruction should reconsider their choice of recreation.

[evm1024]

Another quote from another thread on this topic:

There is an undertone in some posts that "the rules aren't for me" or "I know better." There are decades (in some cases centuries) of experience captured in those rules that people on the seas count on others complying with

I have to agree with this. The rules are based on the collective experience of thousands of mariners. Who are we as individuals to pick and choose which we will follow or to rewrite them as we wish them to be.

Red over red is confusing, white over white is confusing.

In the black of night do we need more confusion?

Clearly if you think that you are not being seen turn on your deck lights. Shine a white light on your sails, sound your horn. These are all allowed and known ways to be seen better. Don't add to the confusion.

[ramblinrod]

Originally Posted by evm1024

Another quote from another thread on this topic:

There is an undertone in some posts that "the rules aren't for me" or "I know better." There are decades (in some cases centuries) of experience captured in those rules that people on the seas count on others complying with

I have to agree with this. The rules are based on the collective experience of thousands of mariners. Who are we as individuals to pick and choose which we will follow or to rewrite them as we wish them to be.

Red over red is confusing, white over white is confusing.

In the black of night do we need more confusion?

Clearly if you think that you are not being seen turn on your deck lights. Shine a white light on your sails, sound your horn. These are all allowed and known ways to be seen better. Don't add to the confusion.

Sigh.

Do Colregs prohibit (though not specifically) displaying both deck level sidelights and masthead located trilights?

It matters not, history dictates, by the testimony given by many here, some are gonna.

If ya'll can't deal with that, you should take up a different profession or pastime.

Y'all may not, but I have bigger fish to fry. Sea ya.

[Dockhead]

Originally Posted by ramblinrod

Sigh.

Do Colregs prohibit (though not specifically) displaying both deck level sidelights and masthead located trilights?

It matters not, history dictates, by the testimony given by many here, some are gonna.

If ya'll can't deal with that, you should take up a different profession or pastime.

Y'all may not, but I have bigger fish to fry. Sea ya.

Yes, they do prohibit displaying a tricolor and deck-level nav lights at the same time. The text of the Rule was cited by someone above. If you want to leave the deck-level nav lights on, then you need not a tricolor, but a Rule 25(c) all-around red over all-around green light at the top of the mast (the "red over green -- sailing machine" lights). These may (actually, must) be used together with the deck level side and stern lights.

Nav lights convey information, information which can be crucial to safety. Besides being illegal, it is exceedingly lubberly to use nav lights in the wrong configuration. As others have said, a tricolor and deck-level stern light displayed together would look exactly like the steaming lights of a large vessel, far away, causing potentially fatal confusion, and the red sector of a tricolor over a red deck level side light can look like RAM. A tricolor together with a steaming light (which you would get automatically if someone wired the tricolor and deck level side lights together) would look exactly like a vessel engaged in fishing, from the port aspect. Why in the world would you not care about causing this kind of confusion? Haven't all of us been sailing at night, saw lights, and really needed to know what we were looking at, and what aspect? Following the Rules concerning nav lights ensures that our lights convey clear information, which someone may really need. They are not there for decoration or just to make a light show -- they convey specific information.

Here are the only three nav light configurations which are acceptable for a vessel under 20 meters under sail:





Putting my lawyer hat on, I can say that if someone got run down and killed in a sailboat displaying wrong nav lights (say by a ship approaching from behind interpreting the two stern lights as two steaming lights far away), as a result of the tricolor and deck level nav lights being incorrectly wired together, I would have the installer's head on a platter in court.



A bit of thread drift, but I like the 25(c) light very much -- it's highly visible and easier to recognize than a tricolor. Only problem with it is that, well there are two problems -- (1) they are not easy to install, as there must be at least a meter of separation between the red and green lamps; and (b) you can't turn off the deck level lights, which mess with your night vision. Maybe really good shielding could solve the second problem.

[evm1024]

Originally Posted by ramblinrod

Sigh.

Do Colregs prohibit (though not specifically) displaying both deck level sidelights and masthead located trilights?

It matters not, history dictates, by the testimony given by many here, some are gonna.

If ya'll can't deal with that, you should take up a different profession or pastime.

Y'all may not, but I have bigger fish to fry. Sea ya.

Really big SIGH

History is also called experience. And in the case of navigation experience shows us what works and what leads to failure. I really don't know why anyone would ignore the experience of generations of mariners to bullheadly go their own way.

I still don't know why it is up for debate? Confusion - bad.

I expect some noobs to show a masthead tricolor and sidelights-stern light thinking that a little is good and more is better. I expect that when presented with the rule against displaying lights that can be confused with valid nav lights to stop showing both. I expect that a greater understanding of the reason for the rules will bring them to a higher lever of the art of small boat operation.

I know that a few will resent being told what to do and how to do it.

As for being told what to do that is the nature of the beast. COLREGS is more than a book that the local marine authority publishes. It is a treaty that is ratified by their respective governments and codified into Law (US Code and Federal rules in the USA).

The prudent mariner follows the rules - the foolish (bold!) mariner makes up their own rules.

[StuM]

Originally Posted by transmitterdan

I see quite a lot of inexperienced sailors running both lights. It is not ok and it is not just a pedantic rule thumper issue to say so. Anyone who is offended by some rule instruction should reconsider their choice of recreation.

And their occupation if they provide marine electrical services.

[StuM]

Originally Posted by ramblinrod

Sigh.

Do Colregs prohibit (though not specifically) displaying both deck level sidelights and masthead located trilights?

It matters not, history dictates, by the testimony given by many here, some are gonna.

If ya'll can't deal with that, you should take up a different profession or pastime.

Y'all may not, but I have bigger fish to fry. Sea ya.

"“Sidelights” means a green light on the starboard side and a red light on the port side each showing an unbroken light over an arc of the horizon of 112.5 degrees and so fixed as to show the light from the right ahead to 22.5 degrees abaft the beam on its respective side. In a vessel of less than 20 metres in length the sidelights may be combined in one lantern carried on the fore and aft centreline of the vessel."
...
" In a sailing vessel of less than 20 metres in length the lights prescribed in paragraph (a) of this Rule may be combined in one lantern carried at or near the top of the mast where it can best be seen."

"a" , "an" "the light", "one lantern" = singular!

"during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character "

Red over red/ white over white CAN be mistaken for other lights specified in the Rules.

Seems fairly clear to me - only display ONE set of sidelights/sternlight, either at/near top of mast or around deck level.

[weavis]

Getting close to being a circuitous discussion and being considered for closing and using as a reference thread.

Either move or on with another topic or forever let it rest..

[ramblinrod]

For what it is worth, I would never wire a trilight together with running lights.

Though I have certainly encountered a number of boats that have had them wired together, and seen several boats where they were displayed together.

Have I advised bad practice? Of course. But it is not my boat and I cannot dictate what the owner does.

I followed a thread many years ago where a gentleman named Finnius was sailing a boat that was mowed down by the local sheriff's deputy high speed power boat. What a mess Finnius had trying not to be found negligent due to incorrect lighting claims by the deputy's lawyers. (The deputy was inebriated and going stupid fast in pitch dark with city light scatter from shore.)

[Uricanejack]

Originally Posted by Dockhead

Did you miss the words "usual" and in "most circumstances"?

I never said "all circumstances." I specifically mentioned, maybe in the other thread, that a few cables can be ok when passing behind, or if you are being overtaken.

In open sea, 1 mile is a good rule to follow, because it is a safe CPA in almost every circumstance, even with a difference in speed, and besides that, this is the distance which the ships you encounter are likely to be using as a minimum CPA (it might be 2 miles in light traffic areas). As I wrote, if you do pass closer than 1 mile, you may cause problems on the ship, where standing orders are likely to require the bridge to call the captain.


But none of that means that a CPA of less than a mile is dangerous in itself, in all circumstances, and I never said that. In open sea, a CPA of less than a mile very often can be, though, so if you do plan to pass closer than that, you had better understand the crossing with good data, better than you can get from a stanchion, unless it's something obvious (obviously passing behind, overtaking, etc.).

Why do ships follow a "rigid rule" like 1 mile or 2 miles? They don't calculate in every case -- can I safely pass 7 cables off? Or 6 cables? Even though such crossing might be pretty safe depending on the geometry. That's because it's bad process, to do it ad hoc, every time. What if you miscalculate once? Why create the work load, when you can just do it the same way every time and know you'll be safe? Good routine, good habits, good process, is what makes safety in something like this -- so you do the safe thing, in muscle memory. So keeping a mile away from every ship in open water is a good policy. You can depart from such a "rigid rule" if you need to -- say because you're dealing with another ship coming from a different direction, and passing a little closer is necessary to make it all work out.

Ships make exceptions for overtaking, but they usually have another "rigid rule" for safe CPA in that case -- 5 cables is common. I've heard them complaining to each other for overtaking closer than that, and of course overtaking is not an inherently safe maneuver (actually the most common type of collision in the North Sea).


*Just as an aside, there is a CHIPS report where one ship complained that one mile was not enough, and that the other ship ignored requests for more room than that, and the first ship was deemed to be in the right.

65 pages of bumph on colregs? must be a record.
I am only halfway.
If I am right. The original hypothetical scenario refers to a small sailing vessel in crossing situation with a large commercial ship. Involving risk of collision in open water. No other vessels? No narrow channel? No TSS.

So why would you keep bringing up the officer of the watch may get in trouble because he will have to call some plonker to the Bridge if the CPA is less than 1 mile.

The Ship is a power driven vessel if the OOW wants a 1 mile CPA he can alter course. It would appear the ship is the give way vessel. Only a total plonker would be calling another plonker. To resolve a simple situation.

The sail boat need do nothing more or less than sail along at his or her pleasure. standing on and maintaining course and speed. Under sail.

1 mile may be an appropriate distance for a ship to act in accordance with rule 17 when stand on. If it is give way the ship should act as per rule 16.

Expecting the sailboat to act under rule 17 at one mile may be reasonable or unreasonable. It is up to the sailboat. Based on its maneuverability. 0.25 of a mile to act according to rule 17 could be considered quite reasonable.


In any event it sure as heck isn't the sailboats fault if some imaginary CPA limit is breached

[Stu Jackson]

Originally Posted by ramblinrod

1. For what it is worth, I would never wire a trilight together with running lights. Though I have certainly encountered a number of boats that have had them wired together, and seen several boats where they were displayed together. Have I advised bad practice? Of course. But it is not my boat and I cannot dictate what the owner does.

2. I followed a thread many years ago where a gentleman named Finnius was sailing a boat that was mowed down by the local sheriff's deputy high speed power boat. What a mess Finnius had trying not to be found negligent due to incorrect lighting claims by the deputy's lawyers. (The deputy was inebriated and going stupid fast in pitch dark with city light scatter from shore.)

1. Good, great. We agree that many of us have seen them being displayed incorrectly. When I mentioned that I had commented on it to another sailor who had them displayed incorrectly, you gave me some grief over it, unnecessarily as I saw it. All I was trying to do was to politely educate him. I believe we owe that to each other as sailors.

2. His name was Bismarck Dinius. He was on an inland lake in Northern California, Clear Lake. I had sailed that lake for many summers in our Catalina 22 in the early 80s. The incorrect lighting you mention was the claim by the sheriff that he didn't have ANY lights on. The only lights the boat he was on had were the deck lights. It was a 22 or so foot sailboat, sailing quietly home on a calm night after doing a race earlier in the day. The sheriff overtook the boat Bismarck was on at high speed in the dark, killing one of the three occupants - the lady who owned the boat. Bismark was at the tiller. It was a gross miscarriage of justice by the "good ol' boys" network in Clearlake. The sheriff was eventually voted out of office. Bismarck lost his job and a big chunk of his life, due to the stupidity and nastiness of a sheriff who should have never been gong that fast; some dispute remains about the sheriff having had a few drinks before leaving his dock. Oddly enough, this example has NO relationship with this subject. At all. False equivalency at best.

[Dockhead]

Originally Posted by Uricanejack

65 pages of bumph on colregs? must be a record.
I am only halfway.
If I am right. The original hypothetical scenario refers to a small sailing vessel in crossing situation with a large commercial ship. Involving risk of collision in open water. No other vessels? No narrow channel? No TSS.

So why would you keep bringing up the officer of the watch may get in trouble because he will have to call some plonker to the Bridge if the CPA is less than 1 mile.

The Ship is a power driven vessel if the OOW wants a 1 mile CPA he can alter course. It would appear the ship is the give way vessel. Only a total plonker would be calling another plonker. To resolve a simple situation.

The sail boat need do nothing more or less than sail along at his or her pleasure. standing on and maintaining course and speed. Under sail.

1 mile may be an appropriate distance for a ship to act in accordance with rule 17 when stand on. If it is give way the ship should act as per rule 16.

Expecting the sailboat to act under rule 17 at one mile may be reasonable or unreasonable. It is up to the sailboat. Based on its maneuverability. 0.25 of a mile to act according to rule 17 could be considered quite reasonable.


In any event it sure as heck isn't the sailboats fault if some imaginary CPA limit is breached

I think you're confusing a 1 mile CPA with "taking action at 1 mile" -- two different things. If you want to maintain a 1 mile CPA, then you need to take action quite a bit earlier than 1 mile off.

This statement:

" The sail boat need do nothing more or less than sail along at his or her pleasure. standing on and maintaining course and speed. Under sail."

Reflects a deep misunderstanding of what it means to be standing on, and of collision avoidance in general. There is no "at his or her pleasure" in collision avoidance at sea -- whether or not you are assigned the role of standing on, or the role of giving way, you are equally responsible for avoiding a collision and equally responsible for maintaining a good watch and good situational awareness, and being ready to take action yourself if necessary when the standing-on phase is over. You are not allowed to just "sail along" and let the ship worry about it -- you have no less responsibility than he does, just because you are supposed to stand on.


As to not caring about the "plonkers" on the bridge of ships you encounter -- well, what can I say about that. Just that that is not the way a good seaman treats others, at sea, or expects to be treated. There are a few exceptions, but commercial mariners mostly treat us with consideration and courtesy, trying not to cause problems for us, despite the fact that many of us cause all kinds of problems for them, through our lack of knowledge and skill.

Normally if the ship is give-way and we are stand-on, the ship will take control of the crossing and set up whatever CPA is required by its standing orders and/or judgement of the OOW. But there are situations, including where we and not the ship are give-way, but also in case we are crossing a narrow channel or fairway, or in case we are maneuvering ourselves from too close, where we can cause a smaller CPA. So, you really don't care, if you cause problems for the guys on the ship?

[evm1024]

Originally Posted by Uricanejack

65 pages of bumph on colregs? must be a record.
I am only halfway.
If I am right. The original hypothetical scenario refers to a small sailing vessel in crossing situation with a large commercial ship. Involving risk of collision in open water. No other vessels? No narrow channel? No TSS.

So why would you keep bringing up the officer of the watch may get in trouble because he will have to call some plonker to the Bridge if the CPA is less than 1 mile.

The Ship is a power driven vessel if the OOW wants a 1 mile CPA he can alter course. It would appear the ship is the give way vessel. Only a total plonker would be calling another plonker. To resolve a simple situation.

The sail boat need do nothing more or less than sail along at his or her pleasure. standing on and maintaining course and speed. Under sail.

1 mile may be an appropriate distance for a ship to act in accordance with rule 17 when stand on. If it is give way the ship should act as per rule 16.

Expecting the sailboat to act under rule 17 at one mile may be reasonable or unreasonable. It is up to the sailboat. Based on its maneuverability. 0.25 of a mile to act according to rule 17 could be considered quite reasonable.


In any event it sure as heck isn't the sailboats fault if some imaginary CPA limit is breached

Hey, Welcome to the thread. Nice to see it go back to Collision Avoidance. And cones of uncertainty.

For my part I base where I as the skipper of the sailboat (under power as I recall) start to get real interested in the crossing situation when the boat is 1 mile from the path of the ship (and the ship 4 miles out). Or more likely as much further out as possible when I see that the ship is heading for a close encounter with me.

I suggest that each of us look at this crossing not as an exercise on paper but to visualize it as if it were unfolding in real time.

The uncertainties are our own speed, the ships speed, the angle at which we will be crossing and where we will be in relation to each other at that crossing.

When we think of this as I'll pass 180' off his stern (CPA of 180') we are running the event backward in time from that point. But in reality we cannot backtrack to understand it, we need to look at this in forward projection from our starting point. For me the starting point is with the ship 4 miles out. And that is just for ease. It might actually be 5 miles out or whatever.

So ship 4 miles out - we know that it is coming our way. Now we are really paying attention to it. All we know is that it is about 14 degrees forward of our beam.

Ship 2 miles out - still 14 degrees forward of our beam. We have realized that we likely are on a collision course. the relative bearing has not changed. And the ship is much closer. And that it only took 6 minutes to get this close.

Ship 1 mile out - still 14 degrees forward of our beam. Crap it is close and moving fast. It only took 3 minutes to get there. We are 0.25 nm and 3 minutes from the intersect but we have no way of knowing that with any certainty. I imagine that there is mild to severe panic on the edges of my mind. What am I going to do to avoid getting run down?

For me if the ship is 4 miles out and is still holding a constant relative bearing then I feel that they have not given way as required and thus I am bound to take corrective action. (17a-ii)

My only experience on the bridge of a (big) ship is with their Transas systems. Great big displays with radar and AIS overlay the charts. If their radar sees our boat we would be on the displays and the bridge crew would be working a solution for the crossing. Plus they "should" have seen us and taken action to avoid a close crossing.

That they did not at 4 miles out tells me it is up to me for whatever reason....

At 4 miles out or wherever I invoke Rule 17a-ii I usually drop my speed to get the other vessel to draw forward of me. I am usually on a track and like to stay on it (check all routes in the GPS/plotter for hazards and going off track triggers another look at the entire new track).

If by a speed change alone the ship does not start drawing forward I will invoke a (typically) 90 degree turn and speed up to attempt to run parallel to them till they draw forward. And if that does not work then I do a further 90 degree turn (reverse my course as it works out to be) to run for cover.

Of course I'm on the radio and making sure that I can be seen and sounding my horn.


Regards