1,000 Boats To Push Flood Waters From Chao Phraya River

[GentlemanJim]

The boats are moored

it doesn't make a blind bit of difference!

[MaxYakov]

ResX and all the others insisting on trying to show numbers with your very very limited understanding of the conservation of energy and conservation of momentum in this particular case. Will you all pleeeeeease give it up. It does not matter if you can prove that the overall result got 1000 m3 of water out of the river mouth .0000001 knot quicker than it originally would have done without the boats. The practical FACT is that in terms of the crisis and the effort to prevent flooding the effort is achieving absolutely NOTHING! All of your attempts at crunching basic numbers is producing figures that are totally meaningless, and do nothing other than exercise your brains in the same way doing a few suduko puzzles would do. So please spare us all from the meaningless drivel that is coming from the keyboards. It is getting really tiresome.

MaxYakov

often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be. -- Lord Kelvin

The key phrase is 'measure'. In this case it does not matter what the numbers are, because they are so small that you cannot measure them to have any meaningful effect, and when Lord Kelvin stated this he was researching into a completely different ball game.

Hi, GentlemanJim! Welcome back! If you're going to quote Lord Kelvin (via my quotation), at least quote him correctly. Crunching basic numbers that are 'totally meaningless' is not the only thing getting tiresome here, IMHO. Do you have any 'suduko' puzzles you could lend us for a while to carry us over the doldrums on this thread?

Edited October 19, 2011 by MaxYakov

[GentlemanJim]

ResX and all the others insisting on trying to show numbers with your very very limited understanding of the conservation of energy and conservation of momentum in this particular case. Will you all pleeeeeease give it up. It does not matter if you can prove that the overall result got 1000 m3 of water out of the river mouth .0000001 knot quicker than it originally would have done without the boats. The practical FACT is that in terms of the crisis and the effort to prevent flooding the effort is achieving absolutely NOTHING! All of your attempts at crunching basic numbers is producing figures that are totally meaningless, and do nothing other than exercise your brains in the same way doing a few suduko puzzles would do. So please spare us all from the meaningless drivel that is coming from the keyboards. It is getting really tiresome.

MaxYakov

often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be. -- Lord Kelvin

The key phrase is 'measure'. In this case it does not matter what the numbers are, because they are so small that you cannot measure them to have any meaningful effect, and when Lord Kelvin stated this he was researching into a completely different ball game.

Hi, GentlemanJim! Welcome back! If you're going to quote Lord Kelvin, at least quote him correctly. Crunching basic numbers that are 'totally meaningless' is not the only thing getting tiresome here, IMHO. Do you have any 'suduko' puzzles you could lend us for a while to carry us over the doldrums on this thread?

you quoted Lord Kelvin MaxYakov. The quote is the one that you posted. What's up? Is your gripe because the 'I' is clipped out at the beginning? How pedantic

Edited October 19, 2011 by GentlemanJim

[wintermute]

Earlier someone was comparing the boats with using pump, the difference that seemed to escape that particular poster is that a pump usually pumps through a pipe or hose from one point to another, so there's only one way the fluid can go, along the pipe, and it doesn't spill along the way.

On a river with insignificant propellers (relative to the size of the river) the water flow pushed back will sooner than later form eddies and waves that will amount to the water moved up and down, sideways and back and forth, the net downriver "thrust" would be negligible.

This has been surmised by others and myself earlier in this thread. When you push water like this it just creates surface currents and surge.

If a person has ever been diving they'd understand how this works. A boat can be anchored and running its propellers and not produce even a tiny bit of noticeable current below 10 meters or so even if you are lined up within the same vertical plane.

All this does is churn water which may have minor effects on surface current but dissipates soon after. The propellers aren't big enough and the channel isn't focused enough to do what they think will work.

[MaxYakov]

ResX and all the others insisting on trying to show numbers with your very very limited understanding of the conservation of energy and conservation of momentum in this particular case. Will you all pleeeeeease give it up. It does not matter if you can prove that the overall result got 1000 m3 of water out of the river mouth .0000001 knot quicker than it originally would have done without the boats. The practical FACT is that in terms of the crisis and the effort to prevent flooding the effort is achieving absolutely NOTHING! All of your attempts at crunching basic numbers is producing figures that are totally meaningless, and do nothing other than exercise your brains in the same way doing a few suduko puzzles would do. So please spare us all from the meaningless drivel that is coming from the keyboards. It is getting really tiresome.

MaxYakov

often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be. -- Lord Kelvin

The key phrase is 'measure'. In this case it does not matter what the numbers are, because they are so small that you cannot measure them to have any meaningful effect, and when Lord Kelvin stated this he was researching into a completely different ball game.

Hi, GentlemanJim! Welcome back! If you're going to quote Lord Kelvin, at least quote him correctly. Crunching basic numbers that are 'totally meaningless' is not the only thing getting tiresome here, IMHO. Do you have any 'suduko' puzzles you could lend us for a while to carry us over the doldrums on this thread?

you quoted Lord Kelvin MaxYakov. The quote is the one that you posted.

No, it isn't. You omitted the leading pronoun somehow and the omission is obvious to one reading the quote. I posted that quote twice and I've checked them both. In the future, if you're going to create a quote box, it's best to document it by placing a 'Name='string'" within the quote brackets, immediately preceding the trailing (right-hand) bracket. In this case, you should have copied the timestamped quote from the post you were replying to. It would have helped me and others trace the source of the quote. I see you have your general HTML more under control than previously. That's a Plus!

What about those suduko puzzles?

Edited October 19, 2011 by MaxYakov

[GentlemanJim]

Hi, GentlemanJim! Welcome back! If you're going to quote Lord Kelvin, at least quote him correctly. Crunching basic numbers that are 'totally meaningless' is not the only thing getting tiresome here, IMHO. Do you have any 'suduko' puzzles you could lend us for a while to carry us over the doldrums on this thread?

you quoted Lord Kelvin MaxYakov. The quote is the one that you posted. What's up? Is your gripe because the 'I' is clipped out at the beginning? How pedantic

No it isn't. You omitted the leading pronoun somehow and the omission is obvious to one reading the quote. I posted that quote twice and I've checked them both. In the future, if you're going to create a quote box, it's best to document it by placing a 'Name='string'" within the quote brackets, immediately preceding the trailing (right-hand) bracket. In this case, you should have copied the timestamped quote from the post you were replying to. It would have helped me and others trace the source of the quote. I see you have your general HTML more under control than previously. That's a Plus!

well it seems you have missed bits of quotes out as well. I have put them in for you just to set the record straight.. Why would you need to trace the source of the quote anyway? You placed the quote. Do you have a problem with short term memory?

To be honest Maxyakov, you have lost a fair bit of credibility there old chap. In the context of the argument and all the number crunching and the supposed results, or not, for you to quirp about me not quoting Kelvin correctly because the 'I' is clipped off the cut and paste is more than pathetic really. All in all it just proves that the pedantic nature of some of the posters here does not allow them to see through the minutia of their arguments and grasp the big practical picture.

I rest my case. Cheerio.

[GentlemanJim]

Max

What about those suduko puzzles?

You're, funny! Really funny! The question is (just as in the river) 'Do you know what I mean'? If the answer is no, I don't believe you, if the answer is yes, then you are the pedant with the limited foresight I have already claimed.

Edited October 19, 2011 by GentlemanJim

[Crushdepth]

I'll try one last time...

Yes, there is an effect. The effect is not zero, it's just NEAR zero. It is so close to zero that it will have NO MEASURABLE IMPACT on river flow or flood levels whatsoever.

<snip>

Agreed - not zero as some say, but very small.

Agreed not zero. In fact the near zero net effect is actually negative due to the boats obstructing the flow while they are pumping water around in small local circles.

As long as no vortexes and turbulence are created downstream it can be sure that the discharge leaving the cross sectional area where we anchor the propellers has increased. When water velocity at that cross sectional area increases then its water level must go down. Other wise conservation of energy will be clearly violated. Google Bernoulli Continuity Equation for more detail. The energy of water at any cross section area is the combination of its potential and kinetic, assuming water is 100% incompressible. Compressibility of water is not an issue at all as far as this discussion is concern. If you increase its kinetic energy then it has to be derived from potential energy. It follows with the water level is going down. This is non debatable scientific fundamental. That is not the main problem why we can't tell whether it works or not.

To me I have two problems to evaluate whether the way it is done right now provides positive impact or near zero. The problems are

(1) After the water that being supplied with kinetic energy loses it kinetic energy it will get back its potential energy. The water level just down stream is actually can be higher than the water level at the cross sectional of interest. In this case it may produce vortexes that circulating near both river banks (near zero velocity region). Or it may not. Probably some might travel downstream and some might produce vortexes. The problem is we don't know such scenario does happen currently and how they address it.

(2) When the water at the cross sectional area of interest gains its kinetic energy its pressure gradient increases. This can be viewed as the manifestation of the river flow has increased . Forget about velocity. It is flow rate that counts. The problem is how far upstream that the discharge can be influenced? I'm sure turbine discharges at Bhumibol and Sirkit cannot be influenced. It doesn't really matter how many boats we use and where we wish to anchor. If it can only effect the area just too small to concern, then what is the point? That is why we have to know control volume (Volume that can be influenced) for each array of boats that we work on. The model of actual control volume is critical to the success of this initiative. The boats have to be arranged according to the desired control volumes. It may have more than one control volume.

Water behind a screw is highly turbulent.

[MaxYakov]

Hi, GentlemanJim! Welcome back! If you're going to quote Lord Kelvin, at least quote him correctly. Crunching basic numbers that are 'totally meaningless' is not the only thing getting tiresome here, IMHO. Do you have any 'suduko' puzzles you could lend us for a while to carry us over the doldrums on this thread?

you quoted Lord Kelvin MaxYakov. The quote is the one that you posted. What's up? Is your gripe because the 'I' is clipped out at the beginning? How pedantic

No it isn't. You omitted the leading pronoun somehow and the omission is obvious to one reading the quote. I posted that quote twice and I've checked them both. In the future, if you're going to create a quote box, it's best to document it by placing a 'Name='string'" within the quote brackets, immediately preceding the trailing (right-hand) bracket. In this case, you should have copied the timestamped quote from the post you were replying to. It would have helped me and others trace the source of the quote. I see you have your general HTML more under control than previously. That's a Plus!

well it seems you have missed bits of quotes out as well. I have put them in for you just to set the record straight.. Why would you need to trace the source of the quote anyway? You placed the quote. Do you have a problem with short term memory?

To be honest Maxyakov, you have lost a fair bit of credibility there old chap. In the context of the argument and all the number crunching and the supposed results, or not, for you to quirp about me not quoting Kelvin correctly because the 'I' is clipped off the cut and paste is more than pathetic really. All in all it just proves that the pedantic nature of some of the posters here does not allow them to see through the minutia of their arguments and grasp the big practical picture.

I rest my case. Cheerio.

Well then ... can I take it that a 'Thank You' for the pedantic quote box tip is entirely out of the question?

P.S: Again, that is MaxYakov, not Maxyakov.

Edited October 19, 2011 by MaxYakov

[GentlemanJim]

Agreed - not zero as some say, but very small.

Agreed not zero. In fact the near zero net effect is actually negative due to the boats obstructing the flow while they are pumping water around in small local circles.

As long as no vortexes and turbulence are created downstream it can be sure that the discharge leaving the cross sectional area where we anchor the propellers has increased. When water velocity at that cross sectional area increases then its water level must go down. Other wise conservation of energy will be clearly violated. Google Bernoulli Continuity Equation for more detail. The energy of water at any cross section area is the combination of its potential and kinetic, assuming water is 100% incompressible. Compressibility of water is not an issue at all as far as this discussion is concern. If you increase its kinetic energy then it has to be derived from potential energy. It follows with the water level is going down. This is non debatable scientific fundamental. That is not the main problem why we can't tell whether it works or not.

To me I have two problems to evaluate whether the way it is done right now provides positive impact or near zero. The problems are

(1) After the water that being supplied with kinetic energy loses it kinetic energy it will get back its potential energy. The water level just down stream is actually can be higher than the water level at the cross sectional of interest. In this case it may produce vortexes that circulating near both river banks (near zero velocity region). Or it may not. Probably some might travel downstream and some might produce vortexes. The problem is we don't know such scenario does happen currently and how they address it.

(2) When the water at the cross sectional area of interest gains its kinetic energy its pressure gradient increases. This can be viewed as the manifestation of the river flow has increased . Forget about velocity. It is flow rate that counts. The problem is how far upstream that the discharge can be influenced? I'm sure turbine discharges at Bhumibol and Sirkit cannot be influenced. It doesn't really matter how many boats we use and where we wish to anchor. If it can only effect the area just too small to concern, then what is the point? That is why we have to know control volume (Volume that can be influenced) for each array of boats that we work on. The model of actual control volume is critical to the success of this initiative. The boats have to be arranged according to the desired control volumes. It may have more than one control volume.

Water behind a screw is highly turbulent.

Exactly correct Crushdepyh.

The thing is ResX that vortexes and turbulence will always occur, so everything else you are pondering after your first line is of absolutely no consequence. You cannot attempt to crunch numbers if you are going to make assumptions that cannot be true. Water from a propellor not only has a linear vector, but also a very complex set of circular motion. Unless you are prepared to include the millions of calculations for the subsequent 'whirlpool' motions in your conservation of momentum calculations then how can the numbers mean anything? I said in a much earlier post, it would take a slick applied mathematician a week or more just to get his head around the basic problem let alone come up with a number.

[Thaddeus]

If we can get away from the number juggling and crossing the t's discussion for a second, I have a quick question.

The ultimate destination for all this water is the sea yes, at sea level, it isn't falling off a cliff like a waterfall.

Is it possible to make the sea accept more water than it wants? does it not just push back?

[GentlemanJim]

you quoted Lord Kelvin MaxYakov. The quote is the one that you posted. What's up? Is your gripe because the 'I' is clipped out at the beginning? How pedantic

No it isn't. You omitted the leading pronoun somehow and the omission is obvious to one reading the quote. I posted that quote twice and I've checked them both. In the future, if you're going to create a quote box, it's best to document it by placing a 'Name='string'" within the quote brackets, immediately preceding the trailing (right-hand) bracket. In this case, you should have copied the timestamped quote from the post you were replying to. It would have helped me and others trace the source of the quote. I see you have your general HTML more under control than previously. That's a Plus!

well it seems you have missed bits of quotes out as well. I have put them in for you just to set the record straight.. Why would you need to trace the source of the quote anyway? You placed the quote. Do you have a problem with short term memory?

To be honest Maxyakov, you have lost a fair bit of credibility there old chap. In the context of the argument and all the number crunching and the supposed results, or not, for you to quirp about me not quoting Kelvin correctly because the 'I' is clipped off the cut and paste is more than pathetic really. All in all it just proves that the pedantic nature of some of the posters here does not allow them to see through the minutia of their arguments and grasp the big practical picture.

I rest my case. Cheerio.

Well then ... can I take it that a 'Thank You' for the pedantic quote box tip is entirely out of the question?

P.S: Again, that is MaxYakov, not Maxyakov.

Entirely.

By the way the Maxyakov was just for you. I was testing your short term memory, and bingo, there is nothing wrong with it., you even say 'P.S Again'. Most confusing then why you needed help because an 'I' was missing to source the quote you put on the forum.

Edited October 19, 2011 by GentlemanJim

[MaxYakov]

Max

What about those suduko puzzles?

You're, funny! Really funny! The question is (just as in the river) 'Do you know what I mean'? If the answer is no, I don't believe you, if the answer is yes, then you are the pedant with the limited foresight I have already claimed.

Yeah, I know. Practice is the key. OK, let's forget the suduko puzzles. But i'm docking you one point for having an undocumented quote box.

What was the part in the middle? -- Kevin Kline as Otto in A Fish Called Wanda, 1988

[Buchholz]

Is it possible to make the sea accept more water than it wants?

Not without a sizable backhander.

[slapout]

Having made a comment when the boats were first proposed and followed this topic for the past few days, I am impressed with some of the input, questions, and possible solutions put forth by members. Granted, I am no expert on fluid flow in rivers, but I feel the volumes being bandied around are pure best guesstimates. If this statement can be acknowledged then there is no absolute measurement of fluid volume nor velocity before hand or after subsequent boat entry into the equation. Thus I do not think anyone can prove/disprove if the original proposal had some merit, as miniscule as it might be..

This is based solely on the apparent lack of accurate measurement of total fluid velocity, fluid viscosity, and an accurate measurement of the dimension of conduit thru which the fluid is flowing. These measurements will have vastly different recorded measurement depending on where they are taken in the conduit thru which the water is flowing.

[MaxYakov]

Well then ... can I take it that a 'Thank You' for the pedantic quote box tip is entirely out of the question?

P.S: Again, that is MaxYakov, not Maxyakov.

Entirely.

By the way the Maxyakov was just for you. I was testing your short term memory, and bingo, there is nothing wrong with it., you even say 'P.S Again'. Most confusing then why you needed help because an 'I' was missing to source the quote you put on the forum.

Surely, you can contrive a conspiracy theory to explain all this.

[thaimite]

In many of the arguments above over the zero or almost zero effect of these boats to the river flow, I keep seeing "Conservation of energy mentioned".

The conservation of energy is ONLY applicable in a CLOSED SYSTEM.

In this context, a closed system has to take in to account all the other effects of the surrounding area such as nature and the weather, gravity. etc etc. The river is NOT a tube in the laboratory with a pump.

Explain the conservation of energy in a windmill or waterfall without taking the above in to account.

As stated before by myself an others, the only means to measure the effect is to measure the flow a significant distance both up and down stream the boats with the engines running and even this is not really any good.

Not having a second indentical river to act as control, you should at least measure the flow without any boats in the river to obstruct the flow.

Now how about those Suduko puzzles

Edited October 19, 2011 by thaimite

[Thaddeus]

Is it possible to make the sea accept more water than it wants?

Not without a sizable backhander.

Not the answer I was looking for, but good effort.

One point

[ResX]

In many of the arguments above over the zero or almost zero effect of these boats to the river flow, I keep seeing "Conservation of energy mentioned".

The conservation of energy is ONLY applicable in a CLOSED SYSTEM.

In this context, a closed system has to take in to account all the other effects of the surrounding area such as nature and the weather, gravity. etc etc. The river is NOT a tube in the laboratory with a pump.

Explain the conservation of energy in a windmill or waterfall without taking the above in to account.

As stated before by myself an others, the only means to measure the effect is to measure the flow a significant distance both up and down stream the boats with the engines running and even this is not really any good.

Not having a second indentical river to act as control, you should at least measure the flow without any boats in the river to obstruct the flow.

Now how about those Suduko puzzles

If you define any cross sectional area that you want then work it out you scientific research there that is your control energy system. When you define energy that the water has at that point you closed energy system, after various cancellation would look like something like this. This equation is derived from the conservation of energy. Term flow rate (Q) will be cancelled out in the operation. Finally you have this.

P/W + V^2/2g +Z = Constant. 1.

That is your closed system. If you add energy to to the system via V^2/2g component in the above equation, then

P/W + V^2/2g + Z = Constant 2.

Constant 2 > Constant 1 if you like to work using positive axis rather than negative axis. When you bring back the equation to energy scale you will see Constant 2 will have higher energy. That obvious right? If you add how you come you get less?

Anyway I know this does not answer the possibility of "100% turbulence will be formed" with this explanation.

[MaxYakov]

Having made a comment when the boats were first proposed and followed this topic for the past few days, I am impressed with some of the input, questions, and possible solutions put forth by members. Granted, I am no expert on fluid flow in rivers, but I feel the volumes being bandied around are pure best guesstimates. If this statement can be acknowledged then there is no absolute measurement of fluid volume nor velocity before hand or after subsequent boat entry into the equation. Thus I do not think anyone can prove/disprove if the original proposal had some merit, as miniscule as it might be..

This is based solely on the apparent lack of accurate measurement of total fluid velocity, fluid viscosity, and an accurate measurement of the dimension of conduit thru which the fluid is flowing. These measurements will have vastly different recorded measurement depending on where they are taken in the conduit thru which the water is flowing.

Good observation. I would say this is bordering on Theoretical Physics :

Theoretical physics is a branch of physics which employs mathemodels and abstractions of physics to rationalize, explain and predict natural phenomena. The importance of mathematics in theoretical physics is sometimes emphasized by expression "mathematical physics".

This is not to say that we do not have some measurements. For instance, today on a Thai TV program, it was stated that the current Chao Phraya flow as 420 x 10³ m³/day (420 million cubic meters per day). This volume is about 60 x 10⁶ m³ greater than some of our previously-used values for daily flow, I believe.

We can take the per day volume and compute the flow in cubic meters per second by dividing it by the number of seconds in a day:

Cubic Meters per Second = 420 x 10³ m³ / 86.4 x 10³ = 4.86 x 10³ m³/sec (4,860 Cubic Meters per Second)

This falls within reasonableness figures we've previously seen on the internet, but on the high side.

I don't mean to be academic about it, but the situation is this: The Ministry of Science and Technology, et al has allegedly asserted that his 'water diversion' effort will (or has, or will have) increase[d] the Chao Phraya's flow to the Bay of Bangkok by 50 million Cubic Meters per day. I believe this value has not been substantiated by any sort formal document. The aim of a few of us is to 'what if' based on his 50 MCM claim to explore its credibility. We're using basic physics and mathematics to do this, although there is sometimes dispute about the basic physics. If that is not solid, then the mathematics is irrelevant.

longway has been working on the mathematical model for determining the theoretical per boat horsepower requirements and fuel consumption for the Minister's stated increased flow rate. Even if the boats didn't contribute much to the increased flow of the Chao Phraya, it is still interesting to see what the fuel consumption and costs theoretically could be. Another way to do this, at the end of the day, is to total all the fuel bills sent to the Minstry of Science and Technology (or wherever), and subtract the inevitable over-charges to arrive at the total fuel consumption. Good Luck with that! The point is that we really don't have to go into extreme detail to arrive at some ballpark estimates and it does get some of us to think about the problem in quantitative and other terms rather than just in political terms. Besides that, it irritates some people to no end.

Hope This Helps

Edited October 19, 2011 by MaxYakov

[Buchholz]

Is it possible to make the sea accept more water than it wants?

Not without a sizable backhander.

Not the answer I was looking for, but good effort.

One point

[bkkjames]

You guys better come to a consensus soon or you will miss the opportunity to prove to yourselves how smart you are

[MaxYakov]

Is it possible to make the sea accept more water than it wants?

Not without a sizable backhander.

Not the answer I was looking for, but good effort.

One point

Having a little CJ are we? That's OK, I've had mine today already and I'm much refreshed now.

[Crushdepth]

I demand that the effect of lunar gravity be incorporated into the discussions. My part of the river flows backwards on a rising tide (at least on the surface, I have not explored the depths of this particular waterway due to the crappy visibility).

[MaxYakov]

I demand that the effect of lunar gravity be incorporated into the discussions. My part of the river flows backwards on a rising tide (at least on the surface, I have not explored the depths of this particular waterway due to the crappy visibility).

Well taken. Tidal effects have been here all the time, superficially at least, in the scheduling of pumping activity by the Minister. I think it's safe to say that the gravity effect causing river flow is overall greater than the tidal effect. Otherwise we'd be perpetually up to our whatever in water. Unfortunately, for many in the Provinces that is, and will be, the case for several months.

[Crushdepth]

I demand that the effect of lunar gravity be incorporated into the discussions. My part of the river flows backwards on a rising tide (at least on the surface, I have not explored the depths of this particular waterway due to the crappy visibility).

Well taken. Tidal effects have been here all the time, superficially at least, in the scheduling of pumping activity by the Minister. I think it's safe to say that the gravity effect causing river flow is overall greater than the tidal effect. Otherwise we'd be perpetually up to our whatever in water. Unfortunately, for many in the Provinces that is, and will be, the case for several months.

Now that I think of it, the canals around my office (north Bangkok, about 20km inland) also flow backwards on a high tide, at least on the larger ones.

[maidu]

no-one is saying the outcome is exactly 0%.

I am saying the outcome is exactly zero effect.

I agree, zero effect on pushing water to the gulf faster than it would ordinarily go.

For its last several Km, the Chao Praya is nearly as flat as a lake. It has a drop of between one and two meters for that distance. That's like putting a piece of paper beneath the legs at one end of a billiard table and saying it's out of plumb. So, any and all water propelled downstream via boat propellers will very soon abut in to a greater mass of water which is at its same level. No net gain. Any speed it acquired by mechanical means will cancel out within ten to twenty meters.

[MaxYakov]

no-one is saying the outcome is exactly 0%.

I am saying the outcome is exactly zero effect.

I agree, zero effect on pushing water to the gulf faster than it would ordinarily go.

For its last several Km, the Chao Praya is nearly as flat as a lake. It has a drop of between one and two meters for that distance. That's like putting a piece of paper beneath the legs at one end of a billiard table and saying it's out of plumb. So, any and all water propelled downstream via boat propellers will very soon abut in to a greater mass of water which is at its same level. No net gain. Any speed it acquired by mechanical means will cancel out within ten to twenty meters.

Which is, no doubt, why the Minister has (allegedly) scheduled his 'water diversion' ops to occur at low tide, in case you missed it. I'm wondering if he's observing that limitation these days or just pumping for PR or psychological or other reasons. I haven't seen any coverage of his pump fleet on Thai TV since Monday (that doesn't mean it wasn't there).

[ResX]

Water behind a screw is highly turbulent.

Then please try to Google (image) - cavitation test propeller

What you are going to see? A huge propeller under test. The propeller is held static and rotating. No. There is no turbulence at all. We can see a few streamlines of vortexes.

Edited October 19, 2011 by metisdead
Repaired quote tags.

[serenitynow]

Water behind a screw is highly turbulent.

Then please try to Google (image) - cavitation test propeller

What you are going to see? A huge propeller under test. The propeller is held static and rotating. No. There is no turbulence at all. We can see a few streamlines of vortexes.

Where there is no turbulence, more often than not it is because the propeller is ducted.