Why do threats come from starboard?

jimbaerselman

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Have yotties ever sat down to consider why most of the nasty situations with big ships occur when the vessel is coming from starboard? It's because, on radar watch, they may not know you're under sail. Also, when visibility is moderate or poor, they may not know you're under sail until too late. How often do they visually scan to identify the return?

Moderate vis, 2 to 5nm - 5 to 12 minutes for a 24kt vessel, give or take an inch. Let's not even think of poor visbility, down to 1000m.

So what's the safe thing to do if you're a vessel under sail aiming to cross a busy shipping lane (I'm not talking TSS, though the answer may be valid for that too) with traffic coming from starboard in moderate or poor visibility? And don't suggest it's to make a dramatic alteration of course to keep out of the way - since you may not be able to see the real threats until too late.
 

FullCircle

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What about if you are on Port tack and the ship is still coming from Starboard. Hah. Bet you never thought of that scenario, eh?

And what about being on Starboard tack with ships coming in from Port. Oh, this gets very complicated.

In the Thames and Estuaries, we force the big boys ships down very narrow channels, just to keep them out of our way.
Except those fishing blokes, they are a bit wearisome, and have fishfinders rather than radars.
 

sighmoon

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In my experience, threats most often come from under the jib, or behind; both places that get forgotten if you're feeling a little lazy.
 

ChrisE

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Erm, on the assumption that we all believe in the maxim that small GRP gives way to big lumps of steel then here's my solution

if the weather's clear then you *should* be able to see your threat and aim at its bum doing this at least 2-3 mins before projected meeting. With this margin of error at a closing speed of say 20 knots that'll leave around a mile between you and the target.

If the weather is murky again you should be able to see your threat on the radar and do likewise, although with radar it is usually more obvious that the threat has made a micro change of course to avoid you and it's surprising how many do.

If it's murky and you haven't got radar then you'll never know what you've missed or missed you /forums/images/graemlins/smile.gif

If you don't agree with the above assumption then best of luck.
 

jamesjermain

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Would it be missing the point to post a serious answer?

You clearly have point to make, Jim, but I'm not sure what it is. If you have radar wait until a risk of collision is apparent then obey Rule 19.

If no radar I would behave as if I was a motor vessel (I could even put the engine on and hoist a cone!) and, again, wait until the risk of collision was obvious before turning clearly but not excessively to starboard to clear his stern by a comfortable margin.

I once sailed with a nervous skipper who, at night, would take bearings on nav lights and almost immediately decide the bearing was steady and order a course change. We spent so much time making huge circles round non-existent threats and then discovering new threats that dawn found us almost exactly where we were at dusk.
 

johnalison

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On the whole I find assessing whether the ship is on a collision-course fairly straightforward, but what I do find hard is judging if the ship has altered course. This is why I will be looking at AIS at my next upgrade (I already have radar).
 

jimbaerselman

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[ QUOTE ]
if the weather's clear then you *should* be able to see your threat and aim at its bum doing this at least 2-3 mins before projected meeting. With this margin of error at a closing speed of say 20 knots that'll leave around a mile between you and the target.


[/ QUOTE ] But what happens if, at that stage, he recognises you as a vessel under sail and starts to alter course to port?
 

jamesjermain

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[ QUOTE ]
But what happens if, at that stage, he recognises you as a vessel under sail and starts to alter course to port?

[/ QUOTE ]

That, of course, is the question. I think I would be more dead now if I always assumed a ship was going to give way to my sail than if I always assumed he would stand on.

I suppose I would resume my previous course and leave the decision making to the ship from then on. To keep turning to starboard would be to invite a collision, would it not?

I think the key is to make a decision and act on it in good time, but not too far ahead - a matter of judgement!
 

jimbaerselman

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James, as you said in your first post, rule 19 should give the answer, but as you've just made clear, it doesn't work, because neither you, nor the larger vessel, know whether you're both obeying the rules for vessels in sight of one another, or rule 19.

I my opinion the answer is to remove any ambiguity. You nearly got there in your first post, but wimped out! [ QUOTE ]
If no radar I would behave as if I was a motor vessel (I could even put the engine on and hoist a cone!) and, again, wait until the risk of collision was obvious before turning clearly but not excessively to starboard to clear his stern by a comfortable margin.

[/ QUOTE ] Exactly. But just go that bit further. Before crossing a known traffic lane coming from starboard in moderate visibility or worse, start the engine, hoist the cone (put steaming light on) and better still, drop or roll the genny/jib. Even drop the main . . .

There is then no ambiguity about who does what. You can aim astern of any vessels you meet, and if and when they see you, they're much less likely to change course at the last minute thinking you're a vessel under sail.

Of course, if you had radar you may be able to identify a sufficient gap not to bother with this routine. But if traffic is dense, do it anyway . . .
 

peterb

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The two problems are first to identify the hazard, and second, to avoid it. You can't start any avoidance until you've identified what it is you are trying to avoid.

If you are approaching a line of ships (TSS or shipping lane) then usually (because of the speed difference) the hazard will be coming from about 70 degrees off your bow. Take bearings of the probable hazards. Initially they will show little change, but gradually the non-hazardous ones will sort themselves out. Once you are certain of the hazard, adjust your course so that the bearing of his stern is changing (slowly) in the correct direction (i.e. if he's going right to left then his bearing should be decreasing and vice versa). The objective is to put yourself on a 'collision course' with one of the gaps.

If I'm doing it I take a piece of graph paper and mark the x-axis for the likely bearings on which I might see hazards. Take bearings of the ships and mark them as dots going across the top of the sheet. A minute or so later, take another set of bearings and mark them as dots along a lower line. Do this a few times, and the real hazard shows up as a vertical line. That's the one you've got to avoid.
 

Stemar

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I seems to me that my speed relative to a biggun is so small that if I've altered course to starboard at any where near the same time as the biggun alters course to port to pass behind me, all I have to do is resume my course and let the biggun get on with it. He's obviously seen me, so will be watching to just what the ~*&~'@ that *&%@#"! WAFI is up to. I'm far more concerned about the buggers that aren't even looking - or, worse, don't care

Or am I missing something?
 

jimi

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Starboard is onlythreatening when the fenders in his greenhouse fail to flourish , so quite a lot really .. I suspect its to do with being stuck in Scotland which is full of rain and dour natives.
 

Krusty

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I think the essence of your post is that a ship's watchkeeper (when there is one)
tends to assume he is the stand-on vessel to anything on his port side, and therefore gives most attention to traffic on his starboard: not surprising, really.
Big ships should not be a problem for a manoevrable yacht with enough wind to make 5 or 6 knots and a willingness to avoid creating a 'risk of collision' situation in which the ship has become the 'give-way' vessel.
So an early alteration of heading, exaggerated for a short time to attract attention, to pass astern of the ship may be the best answer.
It has always worked for me.
 

jimbaerselman

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Stima and Piota, both your observations are quite correct when you have radar, or the visibility is good enough, for you to take avoiding action before some magic range . . . I've assumed it's about 5nm, but it does depend a lot on the size and manoueverability of the oncoming merchantman.

The reason I made this post is that some time back I trawled all my logbooks to check a suspicion. Sure enough, I found that all my really nasty close calls with merchant vessels (six recorded), came from starboard in visibility under 5nm. And no, I had no radar.

In three of those cases I altered course to starboard in order to go astern - and discovered (at varying stages) that the merchant vessels were also changing course.

On the first occasion (don't know the range at which I first saw him, but seemed pretty close at night, so I guess around 2 to 3 miles) I hadn't thought it through and just kept turning (in the end through an uncontrolled circle, so we just stopped dead). I was lucky that he missed, not by much. 100m? difficult to judge at night. Adrenalin leaking out everywhere.

The later two occasions I went back to the original course as soon as I identified a reaction, only to be nearly sideswiped by the stern of one vessel passing metres away. Just because the bow is pointing behind you does not mean that's where the ship is going . . .

On the remaining occasions the other vessels merely maintained course and speed, so altering to starboard was the safe solution.

But all this made me stop and think. There must be a safer way to cross lanes in reduced visibility (<5nm for me, but put your own figure in) when you don't have radar. So now if I know it's a busy bit, I motor across, cones or lights up, sails down to make really sure.

Wimp? For sure. But in those last 25 years I've made a few sharp turns, but I haven't had any more starboard nasties. I have had a nasty one up the stern though! Off Cape Matapan. Now, how should you duck those?
 
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