C&RT License Survey

[Momac]

1 hour ago, Arthur Marshall said:

The error is surely in thinking that where a boat is, is a particular, specific cube made up of boat and water. 

Its not an error.

The lock with the gates and paddles closed is effectively  a specific cube , (or more accurately cuboid).

 

 

Edited December 17, 2023 by MartynG

[Ianws]

It's an interesting discussion but we seem to have fallen down a rabbit hole here. 

 

 

 

 

[Arthur Marshall]

19 minutes ago, MartynG said:

Its not an error.

The lock with the gates and paddles closed is effectively  a specific cube , (or more accurately cuboid).

 

 

Irrelevant. When the boat goes in, the gates and paddles are open. Nothing suddenly changes when you shut the gates, the situation is identical to when they were open.

If i have my toy boat in the bath, and move it from one end to another, nothing changes if I suddenly put a block down the middle of the bath. It can only act as a closed cube if it's shut before the boat goes in, which would involve either a crane, a helicopter, or a bizarre gravitational anomaly.

Just now, Ianws said:

It's an interesting discussion but we seem to have fallen down a rabbit hole here. 

 

But is the hole deeper if it's a BIG rabbit? Or if a badger goes down instead?

[Ianws]

3 minutes ago, Arthur Marshall said:

Irrelevant. When the boat goes in, the gates and paddles are open. Nothing suddenly changes when you shut the gates, the situation is identical to when they were open.

If i have my toy boat in the bath, and move it from one end to another, nothing changes if I suddenly put a block down the middle of the bath. It can only act as a closed cube if it's shut before the boat goes in, which would involve either a crane, a helicopter, or a bizarre gravitational anomaly.

But is the hole deeper if it's a BIG rabbit? Or if a badger goes down instead?

I'll let Alice work that out. 

[magnetman]

Where is the hookah smoking caterpillar? 

 

 

It is impossible for the Boat to make any difference because it is behaving as a shaped piece of water. If there was no Boat the same shaped piece of water would exist anyway. 

 

If a Boat is floating and not moving (situation which occurs during a lock cycle) it is doing nothing other than emulating a shaped piece of water identical to its displacement. 

 

 

It is impossible for it to do anything else unless the displacement is changed,, it goes aground or is placed into or lifted from the water. 

 

It can't happen..

 

Move away from thinking of it as a Boat. Detach the brain from the assumption that you are looking at a Boat. All you are looking at is a shaped piece of water. 

 

 

 

https://youtu.be/OegvynJ1plk?si=8l9Z6818lAo5CkKa

Edited December 17, 2023 by magnetman

[beerbeerbeerbeerbeer]

28 minutes ago, Ianws said:

I'll let Alice work that out. 

I’m going with MartynG’s clear explanation/reasoning,

he had it worked out awhile back,

page 47(?)

 

[magnetman]

MartynG was not right to say that when the Boat leaves the lock it somehow causes the extra water to be sucked back into the lock. 

 

The basic issue here is that a lock with open gates at one end is part of a channel which is a significantly larger container than the closed lock would be. 

 

When the Boat moves out of the lock it is simply an object moving through a channel with the obvious result of moving water. When it is stationary in a lock, which is a container of a fixed size, it is simply a non-moving shaped piece of water exactly the same as an equivalent shaped piece of water which would be in a lock with no Boat in it. 

[beerbeerbeerbeerbeer]

6 minutes ago, magnetman said:

MartynG was not right to say that when the Boat leaves the lock it somehow causes the extra water to be sucked back into the lock. 

 

The basic issue here is that a lock with open gates at one end is part of a channel which is a significantly larger container than the closed lock would be. 

 

When the Boat moves out of the lock it is simply an object moving through a channel with the obvious result of moving water. When it is stationary in a lock, which is a container of a fixed size, it is simply a non-moving shaped piece of water exactly the same as an equivalent shaped piece of water which would be in a lock with no Boat in it. 

 

A closed lock with a boat in has less water than a closed lock without a boat.

?yes?

[magnetman]

The Original Question was how much water is transferred from the higher level to the lower level when a Boat ascends or descends a lock.

 

 

This is a different question to how much water there is in the lock. The lock could be 1000ft deep below the Boat when the lock is empty. 

 

As someone pointed out earlier its like a lift. It makes no difference what is in the lift you still have to move it through the same distance and if the lift was operated by water it would take the same amount of water to operate it regardless of what was in it. 

 

 

 

 

 

I think part of this is rather similar to the idea which humans tend to have revolving around the principle that the world must have 'started' at some point. 

 

This is a basic weakness of humans. Its more than likely that the world never did 'start' and it never will 'end'. Why would either of these things happen? 

 

Humans are limited by their own circumstances and therefore assume this would be the case because of their own start/end experiences and observation of other life forms. 

 

Similarly because it takes more effort for a person to lift something which is heavier there will be a tendency to put importance onto this personal experience and assume that a lock moving a Boat will need to consume more water if the Boat is heavier. 

 

It doesn't work like that. 

[agg221]

38 minutes ago, beerbeerbeerbeerbeer said:

 

A closed lock with a boat in has less water than a closed lock without a boat.

?yes?

Yes.

 

Alec

[beerbeerbeerbeerbeer]

1 minute ago, magnetman said:

The Original Question was how much water is transferred from the higher level to the lower level when a Boat ascends or descends a lock.

 

and if I understand you correctly you’re saying it matters not what size the boat is or if in fact there is a boat at all,

the same volume of water will be transferred 

 

But in my thinking emptying a full lock with a boat will take less water from the pound above than emptying a full lock with no boat,

…that’s all that matters..isn’t it?

just as filling a lock with a boat in it will require less water than filling an empty lock,

 

aren’t you adding the red herring and confusion by suggesting the displacement of water the boat has already created above and will create below the lock are all part and parcel? or am I totally misunderstanding you 🤷‍♀️

 

 

 

 

 

 

[magnetman]

The amount of water moved down hill when operating a lock is the same regardless of what the lock contains.

 

All lock movements including those where the boat goes uphill involve movement of water downhill. 

 

[beerbeerbeerbeerbeer]

7 minutes ago, agg221 said:

Yes.

 

Alec

🍻 

 

and on that logic a bigger boat will take less water from above the lock,

or have I totally missed the point of what’s being said ?

 

[magnetman]

The fact it is a Boat is irrelevant because all a Boat is actually doing once it has been placed in the canal is acting exactly as a block of water the same shape. Nothing else is actually happening here.

 

 

If the Boat was not there the water would be there instead of it. 

 

 

Edited December 18, 2023 by magnetman
typo and bean references

[beerbeerbeerbeerbeer]

2 minutes ago, magnetman said:

The amount of water moved down hill when operating a lock is the same regardless of what the lock contains.

 

All lock movements including those where the boat goes uphill involve movement of water downhill. 

 

Well yes, because water can only flow down hill,  that I can understand 😃

 

3 minutes ago, magnetman said:

The fact it is a Boat is irrelevant because all a Boat is actually doing once it has been placed in the canal is acting exactly as a block of water the same shape. Nothing else is actually happening here.

 

 

If the Boat was not there the water would be there instead of it. 

 

 

but the boat is there,

so the water can’t be there,

and therefore there’ll be less water to move down/up the lock

[magnetman]

9 minutes ago, beerbeerbeerbeerbeer said:

 

aren’t you adding the red herring and confusion by suggesting the displacement of water the boat has already created above and will create below the lock are all part and parcel? or am I totally misunderstanding you 🤷‍♀️

 

 

If you arrr going down a lock this is what happens:

 

Boat goes into lock and pushes the equivalent block of water back into the pound it has come from. 

 

Lock is emptied. 

 

Due to the fact the Boat is acting as a block of water more water needs to be expelled from the lock in order for the levels to equalise and the gates to open. 

 

I suspect you might be thinking of a situation where a lock is only used once rather than the more usual circumstance where the lock is then filled afterwards for the use of a block of water or a Boat going up. 

 

 

2 minutes ago, beerbeerbeerbeerbeer said:

 

but the boat is there,

so the water can’t be there,

and therefore there’ll be less water to move down/up the lock

The Boat IS the Water. Thats the whole point. If the Boat is floating throughout the episode in question it is effectively a block of Water. Nothing else is happening unless the Boat is aground or lifted out. 

 

Its not a Boat. Its a block of Water. 

[Ianws]

The original question in 2022 was about licence increases and affordability. It's moved on. The physics is interesting but is it relevant to who should pay for using the canals? At length we have had good arguments that the size or weight of the boat isn't a factor re. water use and locks. Even if this wasnt the case, given a lot of fatties sit in marinas or only travel occasionally, would it be a major issue anyway? Is the extra licence surcharge just because they are living in a larger vessel on c&rt's water (similar to paying more council tax for a larger house)?

 

 

Edited December 18, 2023 by Ianws
Clarification

[magnetman]

Just charge everyone ten pounds per square foot per yar and sort it out. 

 

 

 

Tell private marinas to source their own water, build their own locks and stank them orf.

 

 

[beerbeerbeerbeerbeer]

11 minutes ago, magnetman said:

 

 

Due to the fact the Boat is acting as a block of water more water needs to be expelled from the lock in order for the levels to equalise and the gates to open. 

 

This bit I don’t get 

 

 

that’s out of context so don’t read right, 

sorry forget it 🤣

I’ll give it a rest

 

Edited December 18, 2023 by beerbeerbeerbeerbeer

[magnetman]

5 minutes ago, beerbeerbeerbeerbeer said:

This bit I don’t get 

Picture needed?

It is easy when you realise that the Boat is just a shaped piece of water. 

Think of the bottom of the lock as being endless. It could be a million miles deep. Just because in your head you know it is about a foot below the Boat when empty is not relevant. If there was not enough space to eject the water taken up by the Boat (water which was theoretically previously saved when entering) then the Boat would no longer be floating. 

 

 

Basically the Boat 'saves' water when entering the lock due to it displacing the water and the lock then becoming a fixed container. When the lock is emptied this 'saved' water is used. 

 

Net result = no water saved regardless of what is in the lock. 

Edited December 18, 2023 by magnetman

[davidg]

8 hours ago, Ianws said:

The original question in 2022 was about licence increases and affordability. It's moved on. The physics is interesting but is it relevant to who should pay for using the canals? At length we have had good arguments that the size or weight of the boat isn't a factor re. water use and locks. Even if this wasnt the case, given a lot of fatties sit in marinas or only travel occasionally, would it be a major issue anyway? Is the extra licence surcharge just because they are living in a larger vessel on c&rt's water (similar to paying more council tax for a larger house)?

 

 

 

Apologies for taking it off track but people were putting forward the argument (probaby tongue in cheek but you never know...) that widebeam boats use less water transiting a lock and should pay less for a licence. Personally I  think it's a great argument, I could load my boat with 30 tons of coal* and get a huge licence reduction if it were true. Unfortunately it isn't.

*I think I may have just spotted another flaw in my cunning money-saving scheme,

[cowpie]

What would happen if a boat is in a full lock and completely leak-free lock, ie all paddles closed. Then you lift a ton of ballast out of the boat?  There will not be a ton of inrushing water into the leak free lock.

Then you drop the ton of ballast into the water but because it is more dense than water it will not replace the full ton of water?

CRT advise me they have yet to find a leak-free lock!

[magnetman]

Try a bath. 

Or a bucket.

[haggis]

I just love how this thread has wandered off and has been conducted without any aggro. Well done guys!

[beerbeerbeerbeerbeer]

9 hours ago, magnetman said:

I suspect you might be thinking of a situation where a lock is only used once rather than the more usual circumstance where the lock is then filled afterwards for the use of a block of water or a Boat going up. 

morning,

 

yes, it’s a single use of lock I’m thinking of, 

what happens with the lock when I leave is irrelevant,

isn’t it?

 

we’re comparing water used by one size of boat with another,