WIndward Boat Keeps Clear?

capnsensible said:
Yum yum Richard, looking forward to this one! ;)
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I sailed out of the river between Isla Canela and Isla Christina in Spain this morning. Downwind, headsail only, Good Twenty knots of breeze. Got weird looks but only sailed by the Lee for a few minutes at a time. No pole. Wouldn't it be great to discover a crossing situation with a risk of collision that really has happened?
 
dolabriform said:
Hi All

I had a situation the other day where I was close hauled on port tack, with a boat approaching at an approximate right angle from starboard who was reaching on a port tack.

My reading of the situation was that we were both on the same tack and as she was the windward boat she should be the give way vessel. But she stood on, made no alteration to course and we were forced to tack away and then tack back around the back of her onto our original course.

My reading of this is based on rule 12, not on rule 15 ( crossing vessels ). I am right in my analysis?

Thanks
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The big question is 'How did this situation arise?'

Colregs are all very unambiguous when two vessels appear to each other from over the horizon.

In everyday coastal situations, it's quite common for the boat who thinks he is stand on to be the keep clear boat, because he should have been keeping clear even before he took notice of the other vessel.

The racing rules are very clear about 'acquiring right of way' and how you may change course when it might affect another boat. You can't do that in colregs.
Also in colregs, when you are close hauled, it is not explicit that you are allowed to luff up when the wind lifts, or even bear off when you are headed by a gust.

Then there's the possibility of the other boat being required to keep clear of a third boat....
 
prv said:
Size of sail only matters if she's square-rigged :)

Otherwise it's "the mainsail" regardless of their relative sizes.

Pete
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If she told you that she was lying :)

On a masthead rig the genoa would probably be totally obscuring the main from that angle. Making it impossible to tell which tack the boat was really on so you have to assume it is starboard
 
TLouth7 said:
Tide affects the two ground tracks differently, for example the track of a boat running downriver won't be affected, while that of a boat close-hauled across the river might change by 45 degrees (putting their tracks at right angles).
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You (or the boat you're about to hit) can't see the ground track. Current has no effect in 'right of way' dynamics.
 
dolabriform said:
Being awkward, what about a situation in fog where you are relying on AIS / Radar to spot the other vessel? Then the ground track would be relevant
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In fog, section III would apply so none of the section II rules apply anyway. Even if they did, you are using exactly the same technique to judge risk of collision (i.e. constant bearing decreasing range). It is not the relative ground track of the vessels that determines responsibilities under section II, it is relative heading.
 
anoccasionalyachtsman said:
You (or the boat you're about to hit) can't see the ground track. Current has no effect in 'right of way' dynamics.
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I agree but OP originally said that the boats were at right-angles. It then transpired that the tracks were at right angles but not the headings. Someone then said that it wouldn't make any difference, implying that the angle between headings and tracks would be the same regardless of tidal flow. I disagree with that, and hopefully demonstrated why it isn't true.

This could cause confusion if relying on AIS tracks, for example a boat that is broad reaching with a cross tide could appear at first glance to be on the opposite tack.
 
LittleSister said:
Unless you are the 'stand on' vessel. (Rule 17(a)(i))
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As discussed earlier you may decide to be courteous and change course or speed before a collision situation really develops, but the big issue with slowing down in that case (to me) is that the courteous action has to be blindingly obvious and exaggerated so the person knows what you are doing, which is fine for a tack or change of course but no good for something as subtle as slowing down. So if slowing down is the only option, then I go with colregs on this one.
 
TLouth7 said:
I agree but OP originally said that the boats were at right-angles. It then transpired that the tracks were at right angles but not the headings. Someone then said that it wouldn't make any difference, implying that the angle between headings and tracks would be the same regardless of tidal flow. I disagree with that, and hopefully demonstrated why it isn't true.

This could cause confusion if relying on AIS tracks, for example a boat that is broad reaching with a cross tide could appear at first glance to be on the opposite tack.
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The plotter tracks change when tide is introduced, but vessels headings and relative bearings certainly don't. Looking at the plotter in a developing situation you should be looking at the relative bearing, not the angle between the tracks.

Edit. Plotters shouldn't be relied on to determine tack/gybes of other vessels, there are other variables.
 
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