The "Making Trees" fallacy appears again...

[Ronny170]

Originally Posted by s/v Jedi

The target is “making trees” when it gets ahead of the EBL. When it stays on the EBL, the VRM shows if it’s coming at you or if it’s moving away from you.

Perhaps I'm just not following your wording, but if EBL is set to and maintained on the target as it travels, then the target is 'moving against trees' if the projected EBL line through the target moves against the background shore or landmarks. The background will always move relative to a moving target (or a moving observing vessel) in this way, unless both boats are on the exact same route or course line.

If that apparent relative movement of the EBL line (maintained on the target boat) moves >forward< against the shoreline with respect to the observing vessel, then the target boat will appear to 'make trees', and a collision might be possible (if range is also decreasing). And if that apparent movement is forward movement ('making trees') AND that apparent forward movement also is changing at a consistent rate over time, then collision is imminent, within the general limitations of the method mentioned earlier.

[s/v Jedi]

Originally Posted by Ronny170

Perhaps I'm just not following your wording, but if EBL is set to and maintained on the target as it travels, then the target is 'moving against trees' if the projected EBL line through the target moves against the background shore or landmarks. The background will always move relative to a moving target (or a moving observing vessel) in this way, unless both boats are on the exact same route or course line.

If that apparent relative movement of the EBL line (maintained on the target boat) moves >forward< against the shoreline with respect to the observing vessel, then the target boat will appear to 'make trees', and a collision might be possible (if range is also decreasing). And if that apparent movement is forward movement ('making trees') AND that apparent forward movement also is changing at a consistent rate over time, then collision is imminent, within the general limitations of the method mentioned earlier.

No you are not rewriting my words, I don’t play the trolling games with you. The EBL is set on the target, as is a VRM circle and that’s it. No maintaining anything on target.

Why do you try to confuse such basic navigation skills, that are taught to every mariner? I suspect you never got the education?

[requiem]

The background moves at a different rate depending on how far away it is compared to how far you've travelled.

If I move forward at a constant rate along with a target vessel that's CBDR, and I shine a laser so it passes just astern of them, then for every 10 meters I travel the laser dot (when it eventually hits something) will also have moved 10 meters. Does that make sense? (I have moved 10 meters forward, the laser is still held pointing the same direction, etc.)

However, from the observing ship, the distance travelled by the dot will appear smaller because it's farther away, and things appear smaller with distance. If the point reflects on a wall 100 meters behind the ship, it may be only a fist-width across as seen from the observer. Still makes sense, yes? So, what about the case when the movement of the dot appears no more than the width of a sewing needle?

[El Pinguino]

Originally Posted by s/v Jedi

No you are not rewriting my words, I don’t play the trolling games with you. The EBL is set on the target, as is a VRM circle and that’s it. No maintaining anything on target.

Why do you try to confuse such basic navigation skills, that are taught to every mariner? I suspect you never got the education?

If using radar then just turn on 'target tails' or whatever it is called on your radar and monitor multiple targets at once.

[Ronny170]

Originally Posted by s/v Jedi

No you are not rewriting my words, I don’t play the trolling games with you. The EBL is set on the target, as is a VRM circle and that’s it. No maintaining anything on target.

Why do you try to confuse such basic navigation skills, that are taught to every mariner? I suspect you never got the education?

Not trolling or rewriting anything, just offering the benefit of clarification on your statement that if "You set an EBL on the target... the target is “making trees” when it gets ahead of the EBL" which implies that if the target remains on EBL with constant relative bearing, that it isn't or won't be "making trees," which is of course not at all a true statement. On collision courses, the target stays at EBL with constant relative bearing AND it is "making trees" against the landscape. If that's what you were saying originally, great, but it didn't read that way to me, that's all. If you were stating something else, then that's on me, and I missed your point.

[Lodesman]

Originally Posted by Ronny170

Not trolling or rewriting anything, just offering the benefit of clarification on your statement ...

Jedi's statement didn't need clarification - it was succinct and clear. You're obfuscating the supposed point of the 'making trees' method. I still can't figure out which side you're on - are you for or against the 'making trees' method?

[Ronny170]

Originally Posted by Lodesman

Jedi's statement didn't need clarification - it was succinct and clear. You're obfuscating the supposed point of the 'making trees' method. I still can't figure out which side you're on - are you for or against the 'making trees' method?

Interesting that you mentioned obfuscating. My original post was about a video discussing a method for assessing collision risk using NO equipment, not even a compass. The purpose was to start a discussion about that method, when and how it works and what its limitations might be. Then it seems that a few people chose to instead make comments without watching the video, or apparently even reading the OP, and started in with their own completely unrelated topics on the thread. And now here we’re talking about using radar and EBL, which is about as far off course from the topic of the thread as we could be, not to mention the unnecessary derogatory comments. Not sure of your definition of obfuscation, but that comes pretty close to it in my book.
To your point that Jedi’s comment “You set an EBL on the target... the target is “making trees” when it gets ahead of the EBL" is succinct and clear, it might be both, but is still nonetheless incorrect. Target can stay right on EBL and be “making trees” at the same time, and never get ahead of EBL. That’s actually exactly what happens with two vessels on collision courses. To me that’s a statement that needs clarification, since clearly the statement was not correct as written, succinct or not. Probably should have ignored irrelevant and off-topic comments, so my mistake there.
To your question, my stance has been made pretty clear I think in my discussions with Requiem and few others on this. Requiem, who despite some terminology issues we are still working through, has remained engaged on topic and brought up some very good points. I’m going to post some diagrams here shortly to hopefully answer the relevant questions that he posed.

The ‘making trees’ method has been around for a long time. It’s not a question of whether it works or not, but rather how and when. A long-standing fallacy or misinterpretation of the method is that if the target boat remains stationary against the land (with decreasing range), then collision is imminent, but if that vessel is ‘making trees’ it will pass in front of you. This is exactly what was stated by a supposed boat captain from NZ and posted online all across social media, getting millions of views. This is not correct, and was discussed in two subsequent videos that I called the ‘rebuttal’ videos. Had anyone watched these videos that I referenced in the OP, all of this would already be abundantly clear. These videos showed that on collision courses, the target boat will in fact ‘make trees’ against the land and not remain stationary as the fallacy goes, and under most common situations will appear to move forward against the shore, and do so at a constant rate. The 'constant rate' part being the key to using the method correctly.

So it’s not as simple as asking whether I or anyone else is ‘for or against’ the trees method, but rather whether what is being observed is also being interpreted correctly. The videos, if anyone bothered to watch, would have gone over at least this much, and much of this confusion and off-topic banter could have been easily avoided.

[Ronny170]

Originally Posted by requiem

I think I was the first to use the phrase "the idea behind the method is to obtain an instantaneous assessment", but Jedi mentioned an "immediate assessment", and we're largely talking about the same thing: being able to determine if another vessel is a hazard with only a brief glance (say, no more than 2-3 seconds).

The other methods described here, whether by compass or that of the rebuttal video, require taking two (compass method) or three (rebuttal method) separate observations to arrive at a similar conclusion. Reading the bearing off the compass is the more efficient of the two, as it only requires two observations, doesn't need any background landmarks, and you don't have to worry so much about some of those special cases mentioned...

I will try to get a diagram posted using some of your suggested scenarios when I return home, to hopefully demonstrate that yes the angle may be small and difficult or impossible to measure with any precision, but that's not what's actually being measured with this method-- it's the 'displacement' of the image of the target boat against the background, and that can be more easily 'seen' or measured, even when the angle differences might be very small. That way we can at least be discussing the same scenario.
I would recommend watching the video again though before that, as much of what you are asking about was covered there in some detail already. For example this method only requires two actual measurements, not three. One initial observation that takes a millisecond, just to see what's behind the target boat initially, and then two measurements at intervals after that. No time needed for the compass needle to stabilize, sight the boat through the compass.... using RBs as you had noted previously.

[thinwater]

This wouldn't get this much discussion in a 7th grade geometry class. It a simple case of triangle proofs. Yes, there are specific situations where the "trees" argument works, just as a broken clock is right twice a day.


Constant bearing. Move on.

[Lodesman]

Originally Posted by Ronny170

Then it seems that a few people chose to instead make comments without watching the video, or apparently even reading the OP, and started in with their own completely unrelated topics on the thread.

Your OP was enigmatic - there's no way to tell what your take was on the videos to which you referred. Your first four respondents all basically supported the supposition proposed in the original video, caveating the limitations of the method.

Originally Posted by Ronny170

And now here we’re talking about using radar and EBL, which is about as far off course from the topic of the thread as we could be, not to mention the unnecessary derogatory comments. Not sure of your definition of obfuscation, but that comes pretty close to it in my book.
To your point that Jedi’s comment “You set an EBL on the target... the target is “making trees” when it gets ahead of the EBL" is succinct and clear, it might be both, but is still nonetheless incorrect. Target can stay right on EBL and be “making trees” at the same time, and never get ahead of EBL. That’s actually exactly what happens with two vessels on collision courses. To me that’s a statement that needs clarification, since clearly the statement was not correct as written, succinct or not.

To say you are making something unclear isn't derogatory; it's a statement of fact.
Jedi's point is that the EBL functions in the same way that the "making trees" method is supposed to function, as it is traditionally used. If the vessel is steady on the EBL, a quick glance would show it not making trees and risk of collision exists. If it moves away from the EBL, you should see it making trees and no risk of collision exists. This all supposes you use the method correctly, not as was shown in either video. Jedi is right, no surprise.

The rebuttal videos show where making trees doesn't work, or where it could give someone a false sense of security. The second video does go into showing how you could measure a constant "advance" of the other boat against the shore, and that would indicate a risk of collision. The author does not seem to endorse using this method, and I and others have stated that it is ridiculously cumbersome, compared to shooting bearings. It is not, and I stress this, the "making trees method". "Making trees" is, as several very experienced mariners stated - an instantaneous or near-instantaneous assessment method.

[Wallaby]

LMAO. How to make the comparatively simple CBDR into a convoluted nightmare of ifs, buts, and maybes.


Standing behind the wheel, or any other fixed 'point', align any other fixed point on your vessel with the TARGET vessel. Stanchion, winch, mast, pulpit etc work--the farther away, the better. Better still, is to align two fixed points on your boat with the target. If the target vessel remains in the same alignment, you have a constant bearing. Now, might be a good time to switch to a compass bearing. Next, figure out if it is coming closer--decreasing range. This can be difficult at night.

Probably obvious, but even if the bearing is not constant, and range is not decreasing, still keep an eye on it.
Do NOT depend on radar. Over the years, I've seen a lot of boats with minimal or NO radar response--offshore, center console fishing boats are the worst offenders, and also hard to see in waves.

[parkstone bay]

Oh dear, how to make life difficult - one can't help it's deliberate as well!
Very simply - and assuming for the moment both vessels maintain their course and speed, (and that is a big assumption, BTW) - if the COMPASS bearing (NB; *NOT* RELATIVE bearing, don't use your stanchions as reference points - things go wrong when you change course due to a windshift) of the other object remains constant, there is a risk of collision. This is in fact the principal of leading marks; if you carry on long enough on the "leading mark" course, you'll hit the nearer mark, and, if you were to carry on even further, you'd hit the second, higher mark as well.
The problem arises for human judgement because, in real life, both vessels don't maintain their course and speed, for all sorts of reasons, but the "Constant Compass Bearing = risk of collision" rule still holds good.
There's the story of the small boat skipper who took sequential compass bearings of a bigger vessel, and found they were changing, therefore , he thought "no chance of a collision"; then he realised that the bearing of the bow of the VLCC was decreasing, while the bearing of the stern was increasing!
But, very simply, if an object isn't apparently moving against the land, there's a definitely a risk of hitting it; if an object *is* apparently moving against the land, there MAY be a risk of hitting it. Take a compass bearing, and see what happens in one, 2, 5 10 minutes.

[s/v Jedi]

Originally Posted by El Pinguino

If using radar then just turn on 'target tails' or whatever it is called on your radar and monitor multiple targets at once.

Yes, you can see if a target is coming at you. It's a newer feature and while I would skip the VRM, if I see a trail indicating that a target is coming at me, I will still put an EBL on it to get more precise info.

Also, you can use ARPA. Normally you need professional grade radars for this but then you can still get MARPA, where you have to point out the target and the radar will calculate CPA, TCPA etc.

I find that most cruisers with radar did nit get any education in the use of radar. It is mind boggling

[clakiep]

Better to check your compass bearing to the crossing vessel. If it stays constant you'll have an encounter - a happy or unhappy one.

Capt. Claus - ocean tramp of the eighties

[danstanford]

Originally Posted by Wallaby

Standing behind the wheel, or any other fixed 'point', align any other fixed point on your vessel with the TARGET vessel. Stanchion, winch, mast, pulpit etc work--the farther away, the better. Better still, is to align two fixed points on your boat with the target. If the target vessel remains in the same alignment, you have a constant bearing. Now, might be a good time to switch to a compass bearing. Next, figure out if it is coming closer--decreasing range. This can be difficult at night.

This is what I have always done. Done before one can take any other steps to get started.