"Doing the dance" when passing

[Arthur Marshall]

I've lost track of who is arguing what. All I know is that when I pass a boat coming towards me, the pointy end swings in towards it as I go past, as does their pointy end towards me, and we all waggle the stick thing on the blunt end to straighten ourselves up.

Whether this accords to the laws of the universe and Newton I have no idea, even after reading all the above.

[Paul C]

Or there's this technique, as used by hirers......

 

 

[TheBiscuits]

I used to wonder how boaters that think they need a twelve foot gap ever manage to get into narrow locks and bridges.

 

Then I looked more closely at the stones and bricks and stopped wondering!

[IanD]

2 minutes ago, Arthur Marshall said:

I've lost track of who is arguing what. All I know is that when I pass a boat coming towards me, the pointy end swings in towards it as I go past, as does their pointy end towards me, and we all waggle the stick thing on the blunt end to straighten ourselves up.

Whether this accords to the laws of the universe and Newton I have no idea, even after reading all the above.

Rest assured, it does... 😉

[Ewan123]

Well that went largely as expected 😂 thank you for the interesting discussion.

[Arthur Marshall]

1 hour ago, Paul C said:

Or there's this technique, as used by hirers......

 

 

And, in some places on the Shroppie, me.

[Ianws]

If all boaters are expected to know this theory and have enough experience to confidently execute it then how on earth are new people going to be integrated into boating. Without enthusiastic new boaters the canals would be more at risk than they already are. As a newbie a boat heading what appears to be straight at you is pretty intimidating, particularly as you can't be certain what their intentions/next steps are. I perfectly understand stepping off on the towpath with a line, if that's what you feel safe with. 

[Tacet]

2 hours ago, nicknorman said:

I find myself in agreement with IanD. Which is worrying!

No no no.  Following Ian's earlier example regarding (expert) papers, you should say that he agrees with you!

 

It seems right to me both in theory and experience too.  Passing in opposite directions is fine, although you can sometimes feel the tails wagging towards each other a little earlier than seems ideal.  Overtaking - and you can get that awful feeling that the boats are going to clash and there is nothing to be done to prevent it.

 

Having said that, I am unsure that there are no circumstances at all in which there will be a flow between two boats passing in opposite directions and I shall now devote myself to thinking of at least one.

[nicknorman]

25 minutes ago, Ianws said:

If all boaters are expected to know this theory and have enough experience to confidently execute it then how on earth are new people going to be integrated into boating. Without enthusiastic new boaters the canals would be more at risk than they already are. As a newbie a boat heading what appears to be straight at you is pretty intimidating, particularly as you can't be certain what their intentions/next steps are. I perfectly understand stepping off on the towpath with a line, if that's what you feel safe with. 

I don’t think you need to know the theory, but it does help to observe a boat’s behaviour under a specific circumstance and realise that this behaviour will be repeated the next time you are in the same circumstance. For example coming out of a wide lock with another boat still in - as you come out, the other boat’s bow will get pulled over towards you and will probably clang, not helped by the other boat tending to move forward to prolong the exposure. And if there isn’t another boat but you are near the side, the back end will be pulled against the wall and scrape unless you apply a moderate amount of rudder to keep the back away from the wall. Better to anticipate the behaviour than to react to it in surprise,
This is all Bernoulli of course and having identified the behaviour, some people like to know the science behind it - but that bit is not mandatory!

[howardang]

11 minutes ago, Tacet said:

 

Having said that, I am unsure that there are no circumstances at all in which there will be a flow between two boats passing in opposite directions and I shall now devote myself to thinking of at least one.

I can give you an example. Most canals are saucer shaped in underwater profile so displaced water may flow  between two passing boats because there isn't enough room for it all to flow down the side nearest the  bank.

 

Howard

[nicknorman]

19 minutes ago, howardang said:

I can give you an example. Most canals are saucer shaped in underwater profile so displaced water may flow  between two passing boats because there isn't enough room for it all to flow down the side nearest the  bank.

 

Howard

All things being equal - similar speeds, drafts, more or less in the centre of the channel, there will be no flow between the boats and hence no suction. If things are not quite equal there may be slight flow, but nothing like as much as bank effect or overtaking effect.

 

Regardless of what theoretical papers may say (and the paper you quoted didn’t say this for opposite direction boats of similar size) in practice there is no tendency for opposite direction narrowboats that pass just a few inches apart, to be pulled / sucked into each other. It just doesn’t happen, and the reason why it doesn’t happen is pretty obvious if you look at the likely fluid flows.

[Ianws]

31 minutes ago, nicknorman said:

I don’t think you need to know the theory, but it does help to observe a boat’s behaviour under a specific circumstance and realise that this behaviour will be repeated the next time you are in the same circumstance. For example coming out of a wide lock with another boat still in - as you come out, the other boat’s bow will get pulled over towards you and will probably clang, not helped by the other boat tending to move forward to prolong the exposure. And if there isn’t another boat but you are near the side, the back end will be pulled against the wall and scrape unless you apply a moderate amount of rudder to keep the back away from the wall. Better to anticipate the behaviour than to react to it in surprise,
This is all Bernoulli of course and having identified the behaviour, some people like to know the science behind it - but that bit is not mandatory!

Agree, but that all comes with experience, which is a good thing. I'm still green but learning. 

[Suzi]

I don't know about so the science bit I love it when I (the boaty) do the "boat dance" 🎉

Edited February 9 by Suzi
make my comments clearer!

[DandV]

And what happens when all this happens on a bend?

Is their a bent bernoulli bypass theorem, or bent bernoulli bang? 

[IanD]

5 hours ago, DandV said:

And what happens when all this happens on a bend?

Is their a bent bernoulli bypass theorem, or bent bernoulli bang? 

 

If the boat coming the other way on a blind band isn't watching or listening for a boat coming the other way, nothing you can do will make much difference... 😞

[blackrose]

That's what one's horn is for. I often sound my horn before blind bends while approaching tentatively and I wish others would do the same thing.

 

But unlike watching for oncoming boats on bends, listening isn't really something one actively has to do, so as long as your horn is loud enough it should alert anyone coming the other way. 

[IanD]

6 hours ago, blackrose said:

That's what one's horn is for. I often sound my horn before blind bends while approaching tentatively and I wish others would do the same thing.

 

But unlike watching for oncoming boats on bends, listening isn't really something one actively has to do, so as long as your horn is loud enough it should alert anyone coming the other way. 

 

Unless they're right above a noisy diesel engine hammering away, or listening to loud music, or possibly both. DAMHIK... 😞

 

P.S. I do the same at blind bends, but not many other people seem to bother -- including slowing down... (see above)

Edited February 19 by IanD

[ditchcrawler]

Or there is a bridge on the bend and every car sounds his horn

[David Mack]

8 hours ago, ditchcrawler said:

Or there is a bridge on the bend and every car sounds his horn

I am tempted to sound the boat's horn when I see a car approaching a hump-backed bridge!

[jam]

On 18/08/2023 at 20:20, Paul C said:

Or there's this technique, as used by hirers......

 

 

Not the best example to use. That is an official passing point on the Llangollen narrows

[beerbeerbeerbeerbeer]

On 19/02/2024 at 07:30, blackrose said:

That's what one's horn is for. I often sound my horn before blind bends while approaching tentatively and I wish others would do the same thing.

 

But unlike watching for oncoming boats on bends, listening isn't really something one actively has to do, so as long as your horn is loud enough it should alert anyone coming the other way. 

the outcome’s still the same though, you still must approach the bridge slowly to see who’s bridge hole it is,

or is it a case of who blows first?