The sinking of MS Estonia: Case Reopened Part VII

[JimOfAllTrades]

Not only that, who would have thought that an investigative body would have assumed that water ingress occurred as the result of water being seen by witnesses to ingress?

"We're flooding!"
"What's your evidence for that?"
"I can see water coming into the boat."
"Now, don't jump to conclusions..."

We're not flooding, just pining for the fjords!

 

[P.J. Denyer]

Again, I'm no engineer, but it seems like the idea is to keep sea water on the outside of the hull. If water is flooding the inside of the hull there might be trouble.

Pedant!

 

[P.J. Denyer]

If you learn to sail in a very small sailing dinghy (called an optimist dinghy, very fittingly, since you have to be one to think you will spend your time in the boat, instead of in the water), you will learn all about turtling. The only difference between a turtle and that dinghy is that you can sometimes get the dinghy to go 360 degrees. Sometimes. Mostly its 180.

As a teenager I did a canoeing course which started with getting out of an inverted canoe. When I did mine my belt got caught on the edge of the seating hole. And the instructor was holding it upside down. That was fun.

 

[catsmate]

Er, because it's on its side.

This is idiotic, even by your mediocre standards.

Capsizing refers to a boat overturning or flipping onto its side, or even upside down, in the water

 

[catsmate]

The only thing I know for sure about turtles is they go all the way down. As did the ship.

And elephants stand on top....

 

[Jack by the hedge]

And elephants stand on top....

Well, that's not gonna help.

 

[JayUtah]

I've always assumed it was simply because an upturned ship's hull looks a bit like a turtle's shell, and is in water, like a turtle (remember, outside the US the land animal is referred to as a 'Tortoise').

Indeed it seems like the question, "What does this have to do with turtles?" has a number of plausible answers. Wikipedia cites to a source that ultimately talks about "putting a turtle on its back by grabbing it by the flipper, and conversely is used to refer to a vessel that has turned upside down, or which has cast off its crew." But it also cites turtleback decking.

If you learn to sail in a very small sailing dinghy ... you will learn all about turtling. The only difference between a turtle and that dinghy is that you can sometimes get the dinghy to go 360 degrees. Sometimes. Mostly it's 180.

Indeed, beginning sailing students spend a lot of time on their beam ends. I learned on a Sunfish class boat, also as a teenager. Its preferred non-upright position is a roll 90º to leeward, but you will occasionally fully turn turtle. The first skill you have to demonstrate as a student is how to right the boat from all manner of non-sailing attitudes.

 

[phiwum]

I've never understood group bullying but as long as it's me and not some other poor sod, that's fne with me as I understand the psychology behind it.

I have to say, you do learn quickly. From the beginning of the sentence to the end, you seem to have progressed a lot.

 

[phiwum]

We're not debating whether a man went to Tesco. We're asking for evidence for your claim that "kemosabe" is Cockney slang for "do you understand?".

Why, exactly, are we debating this again?

And hasn't it been pointlessly debated months, perhaps years ago?

 

[JesseCuster]

Why, exactly, are we debating this again?

And hasn't it been pointlessly debated months, perhaps years ago?

Most of this thread is stuff that has been pointlessly and repeatedly debated months or years ago.

 

[JayUtah]

In attempting to educate Vixen on how gravity creates velocity, she resurrected a topic she apparently now wants to forget. She said,

You have omitted to factor in the resistance of a body of water.

This is evidently her prospective reason to reject the new findings, which will likely conclude that the hole in the side of MS Estonia was caused by contact with the seabed. She says,

So let's see if the forthcoming report can convince sceptics the massive holes in the hull were due to abnormal pointy rocks jabbing through, bearing in mind the resistance from falling into a body of water.

And of course she's the "true" skeptic in this scenario, so her understanding of how it's supposed to work factors into how credible her objection will be.

I would stick my neck out and say I am the sceptic here.

So what does the True Skeptic have to say about the water resistance of a sinking ship?

For a 15,000 tonne vessel to sink in 80 metres of water, it will land with a force of some 803.6 meganewtons. However, that doesn't mean it will ipso facto fracture the ship.

Cont: Post in thread 'The Sinking of MS Estonia: Case Reopened Part V'

May 28, 2023

Well, what actually happened was he found the crack, and saw the rock outcrop that caused it, and left that part out. Even after he'd noted the wreck had shifted since it first sank.




Because in 1994/1995, the ship was laying at an angle that didn't allow divers or ROVs to get under the hull.





The wall fell in 1989. The Soviet Union followed in 1991. The Estonia sank in 1994.



The Russians were being kicked out of Estonia.


And? (spoiler alert, most Soviet gear is borderline line junk. See Ukraine)



And?



Mostly for comic relief.



And?



Which sounds cool unless you...

• Vixen

Now of course she didn't just pull that number out of thin air. She attempted to calculate it with the help of an AI. It was like pulling teeth to get her to admit it was an AI-generated answer. And it was obviously wrong, but we'll get to that.

Now Vixen wants to say:

I didn't claim to solve it, I simply demonstrated that of course it's possible to calculate likely impact on seabed, given the specified dimensions. I am a bean counter, not an engineer, so I wouldn't claim to be able to calculate it myself.

The disavowal is an obvious lie. The link above is an unqualified attempt to solve the problem. The second part is yet another equivocation. She now admits she doesn't know how to calculate hydrodynamic resistance or impact force, but she can still—somehow—demonstrate how to do it, so she's begging you please not to laugh at the Triple-Niner.

Here's her "demonstration." https://internationalskeptics.com/f...nia-case-reopened-part-v.356236/post-14082207 It's an AI-generated post, but she only lately accepted that we found that out. And now it's back in the news because she's referencing it again in hopes you'll still believe she knows something that all the relevant experts are allegedly ignoring. She has the relevant "dimensions" and might be persuaded to explain where the "gravity bit" fits in.

To determine the force exerted when a ship hits the seabed, we need to consider the concept of pressure.

Having done this successfully for decades as a way to make a living, I'd say the first thing too consider is kinetic energy. Everything you want to know about a collision STEMs from that (pun intended). To think about it in terms of force, you want to know the stopping distance. What force does it take to stop an object of mass m moving at velocity v in distance d? Then you can start talking about elastic or plastic responses in the materials, which feeds back into your stopping distance until you converge on an answer. You know you're off to a good start when your AI gets it wrong by the first sentence.

Pressure is defined as force per unit area. We can calculate the force exerted by the ship using the formula:
Force = Pressure × Area

Well, yes, pressure is expressed as force per unit area. That's straight out of the first-year textbook. But then the AI gets the problem backwards. It takes a certain total force to stop a descending ship. That total force isn't multiplied across the contact area; it's divided by it. Two sentences = two errors. The AI is flunking basic physics so far.

Given that the ship hits the seabed at a depth of 80 meters, we need to calculate the pressure at that depth. The pressure in a fluid increases with depth due to the weight of the fluid above.

As I've pointed out numerous times that's the definition of hydrostatic pressure. It has nothing at all whatsoever to do with the water resistance (i.e., hydrodynamic drag) encountered by a sinking object. Hydrostatic pressure is exerted on everything, even on purely stationary objects under water such as the MS Estonia wreck right now as it sits motionless on the seabed. And hydrostatic pressure is isotropic. "Isotropic" is Cockney rhyming slang for "acts in all directions." Hydrodynamic drag affects only moving objects and acts exactly opposite to the object's direction of motion.

The pressure at a specific depth can be calculated using the formula:
Pressure = Density × Gravitational acceleration × Depth

Or in conventional notation:

The density of seawater is typically around 1,025 kilograms per cubic meter, and the gravitational acceleration is approximately 9.8 meters per second squared.

I think that's a little low for the density of seawater, but we know the Baltic isn't as saline as deep ocean so we'll let that ride. We usually want g to at least two decimal places. We'll never know why the AI—brain the size of a planet—is skimping on precision.

Let's calculate the force exerted by the ship:

Pressure = Density × Gravitational acceleration × Depth
= 1,025 kg/m³ × 9.8 m/s² × 80 m
≈ 803,600 Pa (Pascals)

Two boo-boos. First the nitpick, which isn't as much of a nitpick as you might imagine. g—"the gravity bit"—is given here in units of m/s². That's correct when your problem is asking about the acceleration resulting from Earth's gravitation. It's less obviously correct when your problem is asking about force, here the weight of a given mass as it proposes to exert a force. The proper units are N/kg as the strength of Earth's gravitational field at the surface in terms of force per unit mass. This becomes important as we combine the units algebraically to confirm that we got an answer in the units we expected. The numerical value is the same and the congruence of the concepts of gravitational acceleration and gravitational field strength is a proof that first-year students solve as homework.

The gravity bit is correct here, since it's the weight of seawater that we want. But we're talking about a ship sinking. Why does the weight and/or mass of the ship seem to have nothing to with the impact force, which is what the AI thinks it's computing?

The other boo-boo is the omission of the other fluid involved: the atmosphere. The formulation and its solution are more properly :—

where P₀ is mean atmospheric pressure at sea level. That's all the pressure of seawater over a square meter of whatever it is that's down there, without that thing having to be moving. If you need a pressure difference (so-called gauge pressure), then you need to make that rationale part of the problem. And as we've belabored, this number has absolutely nothing to do with either hydrodynamic drag or the velocity with which a sinking ship will hit the bottom. While pressure increases with depth of water, density does not. And it's density, not pressure, that determines hydrodynamic drag.

Next, we need to determine the area over which the force is distributed.

As I explained above, the AI has the problem backwards. It's trying to sew together two physics concepts that are individually correct (albeit both irrelevant), but which don't combine to solve the problem at hand. A competent physics student would notice this and reject the AI's answer.

When you're given pressure per unit area, it's appropriate to multiply that across the affected area to get the total load. That's how you would solve a problem such as a 44 m/s wind blowing against a window of known area. The "standard formula" for fluid dynamic drag I posted some pages back works for wind loading. It can compute the unit pressure of wind of a given density blowing at a given velocity. Then you can multiply by area (ignoring C_D for now) to give the total load.

But as I pointed out, here we deal with a total force that must be divided by the contact area. That total force wasn't computed anywhere in the demonstration because the AI was confused about what was being asked for. We know it's a colossal force because it's the force required to stop a ship moving at a certain velocity in a very short distance. But at this point we don't know what it is.

Without additional information about the shape or size of the ship's contact area, it is difficult to provide an exact value. However, we can assume a simple approximation that the area of contact is the same as the ship's bottom surface area.

Let's say the ship has a bottom surface area of 1000 square meters (just for illustration purposes).

Here the AI has just pulled a number out of its digital backside without any attempt to match it to the "dimensions" of MS Estonia. It's warning Vixen that it has done this, but Vixen either doesn't know what to do with that or doesn't care. Rocks poke holes in ships because even smooth rocks don't have contact areas in the thousands of square meters. The force is concentrated in a small area of the ship's hull.

Force = Pressure × Area
= 803,600 Pa × 1000 m²
= 803,600,000 N (Newtons)

This correctly computes hydrostatic pressure at a depth of 80 meters over an area of 1000 m², but as far as the problem Vixen is claiming to have demonstrated goes, it might just as well be a recipe for salad cream. It could be a thousand square meters of seabed itself, without a shipwreck in sight. And it's irrelevant in a flooded ship, where water pressure increases uniformly on everything and not in a specific direction only.

Yet this is the figure Vixen reports as the answer for how hard the MS Estonia struck the seabed. And this travesty of physics is how she imagines one would "demonstrate" that answer.

Therefore, if the ship weighs 15,000 tonnes and hits the seabed at a depth of 80 meters, it exerts an approximate force of 803,600,000 Newtons (or 803.6 meganewtons) on the seabed.

The competent physics student should have realized at this point that at no time did the solution incorporate the purported mass of the ship. It doesn't take a triple-niner intelligence to understand that a heavier ship lands with greater force than a lighter ship at the same velocity, and that therefore the mass of the ship should have affected the computation somewhere at some time. The 15,000 figure was never "plugged in" anywhere. The AI just mentions it in passing because it was input data.

And I'm pretty sure we already discussed that the 15,000 figure is the gross tonnage of the Estonia, which is a commercially-defined metric that is nonlinearly proportional to the ship's commercially useful volume. It has practically nothing to do with the mass of the ship for physics purposes. It's not proper to refer to it as a "15,000 tonne" ship because gross tonnage doesn't actually have a dimension—certainly not metric tons.

Please note that these calculations are based on estimations and assumptions, and the actual force may vary depending on the ship's design and the specific circumstances of the impact.

Maybe Vixen will one day understand just what kind of heavy lifting this last bit has done. Our fee to a customer for figuring out everything after the comma in that sentence starts at three figures to the left of the comma.

But how about it, @Vixen? Your "demonstration" is fractally wrong, to an extent that would get you a failing grade were you to have submitted this as homework or an exam answer. So what is it that you think you have "demonstrated" with this?

 

[Dabop]

In attempting to educate Vixen on how gravity creates velocity, she resurrected a topic she apparently now wants to forget. She said,

This is evidently her prospective reason to reject the new findings, which will likely conclude that the hole in the side of MS Estonia was caused by contact with the seabed. She says,

And of course she's the "true" skeptic in this scenario, so her understanding of how it's supposed to work factors into how credible her objection will be.


So what does the True Skeptic have to say about the water resistance of a sinking ship?

Cont: Post in thread 'The Sinking of MS Estonia: Case Reopened Part V'

May 28, 2023

Well, what actually happened was he found the crack, and saw the rock outcrop that caused it, and left that part out. Even after he'd noted the wreck had shifted since it first sank.




Because in 1994/1995, the ship was laying at an angle that didn't allow divers or ROVs to get under the hull.





The wall fell in 1989. The Soviet Union followed in 1991. The Estonia sank in 1994.



The Russians were being kicked out of Estonia.


And? (spoiler alert, most Soviet gear is borderline line junk. See Ukraine)



And?



Mostly for comic relief.



And?



Which sounds cool unless you...

• Vixen

Now of course she didn't just pull that number out of thin air. She attempted to calculate it with the help of an AI. It was like pulling teeth to get her to admit it was an AI-generated answer. And it was obviously wrong, but we'll get to that.

Now Vixen wants to say:

The disavowal is an obvious lie. The link above is an unqualified attempt to solve the problem. The second part is yet another equivocation. She now admits she doesn't know how to calculate hydrodynamic resistance or impact force, but she can still—somehow—demonstrate how to do it, so she's begging you please not to laugh at the Triple-Niner.

Here's her "demonstration." https://internationalskeptics.com/f...nia-case-reopened-part-v.356236/post-14082207 It's an AI-generated post, but she only lately accepted that we found that out. And now it's back in the news because she's referencing it again in hopes you'll still believe she knows something that all the relevant experts are allegedly ignoring. She has the relevant "dimensions" and might be persuaded to explain where the "gravity bit" fits in.


Having done this successfully for decades as a way to make a living, I'd say the first thing too consider is kinetic energy. Everything you want to know about a collision STEMs from that (pun intended). To think about it in terms of force, you want to know the stopping distance. What force does it take to stop an object of mass m moving at velocity v in distance d? Then you can start talking about elastic or plastic responses in the materials, which feeds back into your stopping distance until you converge on an answer. You know you're off to a good start when your AI gets it wrong by the first sentence.


Well, yes, pressure is expressed as force per unit area. That's straight out of the first-year textbook. But then the AI gets the problem backwards. It takes a certain total force to stop a descending ship. That total force isn't multiplied across the contact area; it's divided by it. Two sentences = two errors. The AI is flunking basic physics so far.


As I've pointed out numerous times that's the definition of hydrostatic pressure. It has nothing at all whatsoever to do with the water resistance (i.e., hydrodynamic drag) encountered by a sinking object. Hydrostatic pressure is exerted on everything, even on purely stationary objects under water such as the MS Estonia wreck right now as it sits motionless on the seabed. And hydrostatic pressure is isotropic. "Isotropic" is Cockney rhyming slang for "acts in all directions." Hydrodynamic drag affects only moving objects and acts exactly opposite to the object's direction of motion.


Or in conventional notation:

I think that's a little low for the density of seawater, but we know the Baltic isn't as saline as deep ocean so we'll let that ride. We usually want g to at least two decimal places. We'll never know why the AI—brain the size of a planet—is skimping on precision.


Two boo-boos. First the nitpick, which isn't as much of a nitpick as you might imagine. g—"the gravity bit"—is given here in units of m/s². That's correct when your problem is asking about the acceleration resulting from Earth's gravitation. It's less obviously correct when your problem is asking about force, here the weight of a given mass as it proposes to exert a force. The proper units are N/kg as the strength of Earth's gravitational field at the surface in terms of force per unit mass. This becomes important as we combine the units algebraically to confirm that we got an answer in the units we expected. The numerical value is the same and the congruence of the concepts of gravitational acceleration and gravitational field strength is a proof that first-year students solve as homework.

The gravity bit is correct here, since it's the weight of seawater that we want. But we're talking about a ship sinking. Why does the weight and/or mass of the ship seem to have nothing to with the impact force, which is what the AI thinks it's computing?

The other boo-boo is the omission of the other fluid involved: the atmosphere. The formulation and its solution are more properly :—

where P₀ is mean atmospheric pressure at sea level. That's all the pressure of seawater over a square meter of whatever it is that's down there, without that thing having to be moving. If you need a pressure difference (so-called gauge pressure), then you need to make that rationale part of the problem. And as we've belabored, this number has absolutely nothing to do with either hydrodynamic drag or the velocity with which a sinking ship will hit the bottom. While pressure increases with depth of water, density does not. And it's density, not pressure, that determines hydrodynamic drag.


As I explained above, the AI has the problem backwards. It's trying to sew together two physics concepts that are individually correct (albeit both irrelevant), but which don't combine to solve the problem at hand. A competent physics student would notice this and reject the AI's answer.

When you're given pressure per unit area, it's appropriate to multiply that across the affected area to get the total load. That's how you would solve a problem such as a 44 m/s wind blowing against a window of known area. The "standard formula" for fluid dynamic drag I posted some pages back works for wind loading. It can compute the unit pressure of wind of a given density blowing at a given velocity. Then you can multiply by area (ignoring C_D for now) to give the total load.

But as I pointed out, here we deal with a total force that must be divided by the contact area. That total force wasn't computed anywhere in the demonstration because the AI was confused about what was being asked for. We know it's a colossal force because it's the force required to stop a ship moving at a certain velocity in a very short distance. But at this point we don't know what it is.


Here the AI has just pulled a number out of its digital backside without any attempt to match it to the "dimensions" of MS Estonia. It's warning Vixen that it has done this, but Vixen either doesn't know what to do with that or doesn't care. Rocks poke holes in ships because even smooth rocks don't have contact areas in the thousands of square meters. The force is concentrated in a small area of the ship's hull.


This correctly computes hydrostatic pressure at a depth of 80 meters over an area of 1000 m², but as far as the problem Vixen is claiming to have demonstrated goes, it might just as well be a recipe for salad cream. It could be a thousand square meters of seabed itself, without a shipwreck in sight. And it's irrelevant in a flooded ship, where water pressure increases uniformly on everything and not in a specific direction only.

Yet this is the figure Vixen reports as the answer for how hard the MS Estonia struck the seabed. And this travesty of physics is how she imagines one would "demonstrate" that answer.


The competent physics student should have realized at this point that at no time did the solution incorporate the purported mass of the ship. It doesn't take a triple-niner intelligence to understand that a heavier ship lands with greater force than a lighter ship at the same velocity, and that therefore the mass of the ship should have affected the computation somewhere at some time. The 15,000 figure was never "plugged in" anywhere. The AI just mentions it in passing because it was input data.

And I'm pretty sure we already discussed that the 15,000 figure is the gross tonnage of the Estonia, which is a commercially-defined metric that is nonlinearly proportional to the ship's commercially useful volume. It has practically nothing to do with the mass of the ship for physics purposes. It's not proper to refer to it as a "15,000 tonne" ship because gross tonnage doesn't actually have a dimension—certainly not metric tons.


Maybe Vixen will one day understand just what kind of heavy lifting this last bit has done. Our fee to a customer for figuring out everything after the comma in that sentence starts at three figures to the left of the comma.

But how about it, @Vixen? Your "demonstration" is fractally wrong, to an extent that would get you a failing grade were you to have submitted this as homework or an exam answer. So what is it that you think you have "demonstrated" with this?

Whats scary is that I actually understood that explanation (thanks Jay) and was able to follow it all....
I couldn't have dont it myself without a lot of 'figuring out' how to do it (and quite frankly I wouldn't be bothered to myself)- but then the last time I did actual Physics studies was back when I was in high school in the early 1980's!!!!!
But I was easily able to follow the explanation....and I have no doubt that Jay know what he's talking about (well aware of his 'body of work' going back a couple of decades now- has it really been THAT long??? wow...)
(will our 999'r????- well I know what I think will happen lol)

 

[Helen]

In attempting to educate Vixen on how gravity creates velocity, she resurrected a topic she apparently now wants to forget. She said,

This is evidently her prospective reason to reject the new findings, which will likely conclude that the hole in the side of MS Estonia was caused by contact with the seabed. She says,

And of course she's the "true" skeptic in this scenario, so her understanding of how it's supposed to work factors into how credible her objection will be.


So what does the True Skeptic have to say about the water resistance of a sinking ship?

Cont: Post in thread 'The Sinking of MS Estonia: Case Reopened Part V'

May 28, 2023

Well, what actually happened was he found the crack, and saw the rock outcrop that caused it, and left that part out. Even after he'd noted the wreck had shifted since it first sank.




Because in 1994/1995, the ship was laying at an angle that didn't allow divers or ROVs to get under the hull.





The wall fell in 1989. The Soviet Union followed in 1991. The Estonia sank in 1994.



The Russians were being kicked out of Estonia.


And? (spoiler alert, most Soviet gear is borderline line junk. See Ukraine)



And?



Mostly for comic relief.



And?



Which sounds cool unless you...

• Vixen

Now of course she didn't just pull that number out of thin air. She attempted to calculate it with the help of an AI. It was like pulling teeth to get her to admit it was an AI-generated answer. And it was obviously wrong, but we'll get to that.

Now Vixen wants to say:

The disavowal is an obvious lie. The link above is an unqualified attempt to solve the problem. The second part is yet another equivocation. She now admits she doesn't know how to calculate hydrodynamic resistance or impact force, but she can still—somehow—demonstrate how to do it, so she's begging you please not to laugh at the Triple-Niner.

Here's her "demonstration." https://internationalskeptics.com/f...nia-case-reopened-part-v.356236/post-14082207 It's an AI-generated post, but she only lately accepted that we found that out. And now it's back in the news because she's referencing it again in hopes you'll still believe she knows something that all the relevant experts are allegedly ignoring. She has the relevant "dimensions" and might be persuaded to explain where the "gravity bit" fits in.


Having done this successfully for decades as a way to make a living, I'd say the first thing too consider is kinetic energy. Everything you want to know about a collision STEMs from that (pun intended). To think about it in terms of force, you want to know the stopping distance. What force does it take to stop an object of mass m moving at velocity v in distance d? Then you can start talking about elastic or plastic responses in the materials, which feeds back into your stopping distance until you converge on an answer. You know you're off to a good start when your AI gets it wrong by the first sentence.


Well, yes, pressure is expressed as force per unit area. That's straight out of the first-year textbook. But then the AI gets the problem backwards. It takes a certain total force to stop a descending ship. That total force isn't multiplied across the contact area; it's divided by it. Two sentences = two errors. The AI is flunking basic physics so far.


As I've pointed out numerous times that's the definition of hydrostatic pressure. It has nothing at all whatsoever to do with the water resistance (i.e., hydrodynamic drag) encountered by a sinking object. Hydrostatic pressure is exerted on everything, even on purely stationary objects under water such as the MS Estonia wreck right now as it sits motionless on the seabed. And hydrostatic pressure is isotropic. "Isotropic" is Cockney rhyming slang for "acts in all directions." Hydrodynamic drag affects only moving objects and acts exactly opposite to the object's direction of motion.


Or in conventional notation:

I think that's a little low for the density of seawater, but we know the Baltic isn't as saline as deep ocean so we'll let that ride. We usually want g to at least two decimal places. We'll never know why the AI—brain the size of a planet—is skimping on precision.


Two boo-boos. First the nitpick, which isn't as much of a nitpick as you might imagine. g—"the gravity bit"—is given here in units of m/s². That's correct when your problem is asking about the acceleration resulting from Earth's gravitation. It's less obviously correct when your problem is asking about force, here the weight of a given mass as it proposes to exert a force. The proper units are N/kg as the strength of Earth's gravitational field at the surface in terms of force per unit mass. This becomes important as we combine the units algebraically to confirm that we got an answer in the units we expected. The numerical value is the same and the congruence of the concepts of gravitational acceleration and gravitational field strength is a proof that first-year students solve as homework.

The gravity bit is correct here, since it's the weight of seawater that we want. But we're talking about a ship sinking. Why does the weight and/or mass of the ship seem to have nothing to with the impact force, which is what the AI thinks it's computing?

The other boo-boo is the omission of the other fluid involved: the atmosphere. The formulation and its solution are more properly :—

where P₀ is mean atmospheric pressure at sea level. That's all the pressure of seawater over a square meter of whatever it is that's down there, without that thing having to be moving. If you need a pressure difference (so-called gauge pressure), then you need to make that rationale part of the problem. And as we've belabored, this number has absolutely nothing to do with either hydrodynamic drag or the velocity with which a sinking ship will hit the bottom. While pressure increases with depth of water, density does not. And it's density, not pressure, that determines hydrodynamic drag.


As I explained above, the AI has the problem backwards. It's trying to sew together two physics concepts that are individually correct (albeit both irrelevant), but which don't combine to solve the problem at hand. A competent physics student would notice this and reject the AI's answer.

When you're given pressure per unit area, it's appropriate to multiply that across the affected area to get the total load. That's how you would solve a problem such as a 44 m/s wind blowing against a window of known area. The "standard formula" for fluid dynamic drag I posted some pages back works for wind loading. It can compute the unit pressure of wind of a given density blowing at a given velocity. Then you can multiply by area (ignoring C_D for now) to give the total load.

But as I pointed out, here we deal with a total force that must be divided by the contact area. That total force wasn't computed anywhere in the demonstration because the AI was confused about what was being asked for. We know it's a colossal force because it's the force required to stop a ship moving at a certain velocity in a very short distance. But at this point we don't know what it is.


Here the AI has just pulled a number out of its digital backside without any attempt to match it to the "dimensions" of MS Estonia. It's warning Vixen that it has done this, but Vixen either doesn't know what to do with that or doesn't care. Rocks poke holes in ships because even smooth rocks don't have contact areas in the thousands of square meters. The force is concentrated in a small area of the ship's hull.


This correctly computes hydrostatic pressure at a depth of 80 meters over an area of 1000 m², but as far as the problem Vixen is claiming to have demonstrated goes, it might just as well be a recipe for salad cream. It could be a thousand square meters of seabed itself, without a shipwreck in sight. And it's irrelevant in a flooded ship, where water pressure increases uniformly on everything and not in a specific direction only.

Yet this is the figure Vixen reports as the answer for how hard the MS Estonia struck the seabed. And this travesty of physics is how she imagines one would "demonstrate" that answer.


The competent physics student should have realized at this point that at no time did the solution incorporate the purported mass of the ship. It doesn't take a triple-niner intelligence to understand that a heavier ship lands with greater force than a lighter ship at the same velocity, and that therefore the mass of the ship should have affected the computation somewhere at some time. The 15,000 figure was never "plugged in" anywhere. The AI just mentions it in passing because it was input data.

And I'm pretty sure we already discussed that the 15,000 figure is the gross tonnage of the Estonia, which is a commercially-defined metric that is nonlinearly proportional to the ship's commercially useful volume. It has practically nothing to do with the mass of the ship for physics purposes. It's not proper to refer to it as a "15,000 tonne" ship because gross tonnage doesn't actually have a dimension—certainly not metric tons.


Maybe Vixen will one day understand just what kind of heavy lifting this last bit has done. Our fee to a customer for figuring out everything after the comma in that sentence starts at three figures to the left of the comma.

But how about it, @Vixen? Your "demonstration" is fractally wrong, to an extent that would get you a failing grade were you to have submitted this as homework or an exam answer. So what is it that you think you have "demonstrated" with this?

Easy for you to say.


(As in easy, if you have the knowledge, and know how to express so that even i can understand it)

 

[wollery]

In attempting to educate Vixen on how gravity creates velocity, she resurrected a topic she apparently now wants to forget. She said,

This is evidently her prospective reason to reject the new findings, which will likely conclude that the hole in the side of MS Estonia was caused by contact with the seabed. She says,

And of course she's the "true" skeptic in this scenario, so her understanding of how it's supposed to work factors into how credible her objection will be.


So what does the True Skeptic have to say about the water resistance of a sinking ship?

Cont: Post in thread 'The Sinking of MS Estonia: Case Reopened Part V'

May 28, 2023

Well, what actually happened was he found the crack, and saw the rock outcrop that caused it, and left that part out. Even after he'd noted the wreck had shifted since it first sank.




Because in 1994/1995, the ship was laying at an angle that didn't allow divers or ROVs to get under the hull.





The wall fell in 1989. The Soviet Union followed in 1991. The Estonia sank in 1994.



The Russians were being kicked out of Estonia.


And? (spoiler alert, most Soviet gear is borderline line junk. See Ukraine)



And?



Mostly for comic relief.



And?



Which sounds cool unless you...

• Vixen

Now of course she didn't just pull that number out of thin air. She attempted to calculate it with the help of an AI. It was like pulling teeth to get her to admit it was an AI-generated answer. And it was obviously wrong, but we'll get to that.

Now Vixen wants to say:

The disavowal is an obvious lie. The link above is an unqualified attempt to solve the problem. The second part is yet another equivocation. She now admits she doesn't know how to calculate hydrodynamic resistance or impact force, but she can still—somehow—demonstrate how to do it, so she's begging you please not to laugh at the Triple-Niner.

Here's her "demonstration." https://internationalskeptics.com/f...nia-case-reopened-part-v.356236/post-14082207 It's an AI-generated post, but she only lately accepted that we found that out. And now it's back in the news because she's referencing it again in hopes you'll still believe she knows something that all the relevant experts are allegedly ignoring. She has the relevant "dimensions" and might be persuaded to explain where the "gravity bit" fits in.


Having done this successfully for decades as a way to make a living, I'd say the first thing too consider is kinetic energy. Everything you want to know about a collision STEMs from that (pun intended). To think about it in terms of force, you want to know the stopping distance. What force does it take to stop an object of mass m moving at velocity v in distance d? Then you can start talking about elastic or plastic responses in the materials, which feeds back into your stopping distance until you converge on an answer. You know you're off to a good start when your AI gets it wrong by the first sentence.


Well, yes, pressure is expressed as force per unit area. That's straight out of the first-year textbook. But then the AI gets the problem backwards. It takes a certain total force to stop a descending ship. That total force isn't multiplied across the contact area; it's divided by it. Two sentences = two errors. The AI is flunking basic physics so far.


As I've pointed out numerous times that's the definition of hydrostatic pressure. It has nothing at all whatsoever to do with the water resistance (i.e., hydrodynamic drag) encountered by a sinking object. Hydrostatic pressure is exerted on everything, even on purely stationary objects under water such as the MS Estonia wreck right now as it sits motionless on the seabed. And hydrostatic pressure is isotropic. "Isotropic" is Cockney rhyming slang for "acts in all directions." Hydrodynamic drag affects only moving objects and acts exactly opposite to the object's direction of motion.


Or in conventional notation:

I think that's a little low for the density of seawater, but we know the Baltic isn't as saline as deep ocean so we'll let that ride. We usually want g to at least two decimal places. We'll never know why the AI—brain the size of a planet—is skimping on precision.


Two boo-boos. First the nitpick, which isn't as much of a nitpick as you might imagine. g—"the gravity bit"—is given here in units of m/s². That's correct when your problem is asking about the acceleration resulting from Earth's gravitation. It's less obviously correct when your problem is asking about force, here the weight of a given mass as it proposes to exert a force. The proper units are N/kg as the strength of Earth's gravitational field at the surface in terms of force per unit mass. This becomes important as we combine the units algebraically to confirm that we got an answer in the units we expected. The numerical value is the same and the congruence of the concepts of gravitational acceleration and gravitational field strength is a proof that first-year students solve as homework.

The gravity bit is correct here, since it's the weight of seawater that we want. But we're talking about a ship sinking. Why does the weight and/or mass of the ship seem to have nothing to with the impact force, which is what the AI thinks it's computing?

The other boo-boo is the omission of the other fluid involved: the atmosphere. The formulation and its solution are more properly :—

where P₀ is mean atmospheric pressure at sea level. That's all the pressure of seawater over a square meter of whatever it is that's down there, without that thing having to be moving. If you need a pressure difference (so-called gauge pressure), then you need to make that rationale part of the problem. And as we've belabored, this number has absolutely nothing to do with either hydrodynamic drag or the velocity with which a sinking ship will hit the bottom. While pressure increases with depth of water, density does not. And it's density, not pressure, that determines hydrodynamic drag.


As I explained above, the AI has the problem backwards. It's trying to sew together two physics concepts that are individually correct (albeit both irrelevant), but which don't combine to solve the problem at hand. A competent physics student would notice this and reject the AI's answer.

When you're given pressure per unit area, it's appropriate to multiply that across the affected area to get the total load. That's how you would solve a problem such as a 44 m/s wind blowing against a window of known area. The "standard formula" for fluid dynamic drag I posted some pages back works for wind loading. It can compute the unit pressure of wind of a given density blowing at a given velocity. Then you can multiply by area (ignoring C_D for now) to give the total load.

But as I pointed out, here we deal with a total force that must be divided by the contact area. That total force wasn't computed anywhere in the demonstration because the AI was confused about what was being asked for. We know it's a colossal force because it's the force required to stop a ship moving at a certain velocity in a very short distance. But at this point we don't know what it is.


Here the AI has just pulled a number out of its digital backside without any attempt to match it to the "dimensions" of MS Estonia. It's warning Vixen that it has done this, but Vixen either doesn't know what to do with that or doesn't care. Rocks poke holes in ships because even smooth rocks don't have contact areas in the thousands of square meters. The force is concentrated in a small area of the ship's hull.


This correctly computes hydrostatic pressure at a depth of 80 meters over an area of 1000 m², but as far as the problem Vixen is claiming to have demonstrated goes, it might just as well be a recipe for salad cream. It could be a thousand square meters of seabed itself, without a shipwreck in sight. And it's irrelevant in a flooded ship, where water pressure increases uniformly on everything and not in a specific direction only.

Yet this is the figure Vixen reports as the answer for how hard the MS Estonia struck the seabed. And this travesty of physics is how she imagines one would "demonstrate" that answer.


The competent physics student should have realized at this point that at no time did the solution incorporate the purported mass of the ship. It doesn't take a triple-niner intelligence to understand that a heavier ship lands with greater force than a lighter ship at the same velocity, and that therefore the mass of the ship should have affected the computation somewhere at some time. The 15,000 figure was never "plugged in" anywhere. The AI just mentions it in passing because it was input data.

And I'm pretty sure we already discussed that the 15,000 figure is the gross tonnage of the Estonia, which is a commercially-defined metric that is nonlinearly proportional to the ship's commercially useful volume. It has practically nothing to do with the mass of the ship for physics purposes. It's not proper to refer to it as a "15,000 tonne" ship because gross tonnage doesn't actually have a dimension—certainly not metric tons.


Maybe Vixen will one day understand just what kind of heavy lifting this last bit has done. Our fee to a customer for figuring out everything after the comma in that sentence starts at three figures to the left of the comma.

But how about it, @Vixen? Your "demonstration" is fractally wrong, to an extent that would get you a failing grade were you to have submitted this as homework or an exam answer. So what is it that you think you have "demonstrated" with this?

I hadn’t actually seen Vixen’s calculations on this before.

I teach A level physics, and if one of my students offered up this dog’s dinner, I’d ask them if they’d been sleeping in class!

 

[Steve]

In attempting to educate Vixen on how gravity creates velocity, she resurrected a topic she apparently now wants to forget. She said,

This is evidently her prospective reason to reject the new findings, which will likely conclude that the hole in the side of MS Estonia was caused by contact with the seabed. She says,

And of course she's the "true" skeptic in this scenario, so her understanding of how it's supposed to work factors into how credible her objection will be.


So what does the True Skeptic have to say about the water resistance of a sinking ship?

Cont: Post in thread 'The Sinking of MS Estonia: Case Reopened Part V'

May 28, 2023

Well, what actually happened was he found the crack, and saw the rock outcrop that caused it, and left that part out. Even after he'd noted the wreck had shifted since it first sank.




Because in 1994/1995, the ship was laying at an angle that didn't allow divers or ROVs to get under the hull.





The wall fell in 1989. The Soviet Union followed in 1991. The Estonia sank in 1994.



The Russians were being kicked out of Estonia.


And? (spoiler alert, most Soviet gear is borderline line junk. See Ukraine)



And?



Mostly for comic relief.



And?



Which sounds cool unless you...

• Vixen

Now of course she didn't just pull that number out of thin air. She attempted to calculate it with the help of an AI. It was like pulling teeth to get her to admit it was an AI-generated answer. And it was obviously wrong, but we'll get to that.

Now Vixen wants to say:

The disavowal is an obvious lie. The link above is an unqualified attempt to solve the problem. The second part is yet another equivocation. She now admits she doesn't know how to calculate hydrodynamic resistance or impact force, but she can still—somehow—demonstrate how to do it, so she's begging you please not to laugh at the Triple-Niner.

Here's her "demonstration." https://internationalskeptics.com/f...nia-case-reopened-part-v.356236/post-14082207 It's an AI-generated post, but she only lately accepted that we found that out. And now it's back in the news because she's referencing it again in hopes you'll still believe she knows something that all the relevant experts are allegedly ignoring. She has the relevant "dimensions" and might be persuaded to explain where the "gravity bit" fits in.


Having done this successfully for decades as a way to make a living, I'd say the first thing too consider is kinetic energy. Everything you want to know about a collision STEMs from that (pun intended). To think about it in terms of force, you want to know the stopping distance. What force does it take to stop an object of mass m moving at velocity v in distance d? Then you can start talking about elastic or plastic responses in the materials, which feeds back into your stopping distance until you converge on an answer. You know you're off to a good start when your AI gets it wrong by the first sentence.


Well, yes, pressure is expressed as force per unit area. That's straight out of the first-year textbook. But then the AI gets the problem backwards. It takes a certain total force to stop a descending ship. That total force isn't multiplied across the contact area; it's divided by it. Two sentences = two errors. The AI is flunking basic physics so far.


As I've pointed out numerous times that's the definition of hydrostatic pressure. It has nothing at all whatsoever to do with the water resistance (i.e., hydrodynamic drag) encountered by a sinking object. Hydrostatic pressure is exerted on everything, even on purely stationary objects under water such as the MS Estonia wreck right now as it sits motionless on the seabed. And hydrostatic pressure is isotropic. "Isotropic" is Cockney rhyming slang for "acts in all directions." Hydrodynamic drag affects only moving objects and acts exactly opposite to the object's direction of motion.


Or in conventional notation:

I think that's a little low for the density of seawater, but we know the Baltic isn't as saline as deep ocean so we'll let that ride. We usually want g to at least two decimal places. We'll never know why the AI—brain the size of a planet—is skimping on precision.


Two boo-boos. First the nitpick, which isn't as much of a nitpick as you might imagine. g—"the gravity bit"—is given here in units of m/s². That's correct when your problem is asking about the acceleration resulting from Earth's gravitation. It's less obviously correct when your problem is asking about force, here the weight of a given mass as it proposes to exert a force. The proper units are N/kg as the strength of Earth's gravitational field at the surface in terms of force per unit mass. This becomes important as we combine the units algebraically to confirm that we got an answer in the units we expected. The numerical value is the same and the congruence of the concepts of gravitational acceleration and gravitational field strength is a proof that first-year students solve as homework.

The gravity bit is correct here, since it's the weight of seawater that we want. But we're talking about a ship sinking. Why does the weight and/or mass of the ship seem to have nothing to with the impact force, which is what the AI thinks it's computing?

The other boo-boo is the omission of the other fluid involved: the atmosphere. The formulation and its solution are more properly :—

where P₀ is mean atmospheric pressure at sea level. That's all the pressure of seawater over a square meter of whatever it is that's down there, without that thing having to be moving. If you need a pressure difference (so-called gauge pressure), then you need to make that rationale part of the problem. And as we've belabored, this number has absolutely nothing to do with either hydrodynamic drag or the velocity with which a sinking ship will hit the bottom. While pressure increases with depth of water, density does not. And it's density, not pressure, that determines hydrodynamic drag.


As I explained above, the AI has the problem backwards. It's trying to sew together two physics concepts that are individually correct (albeit both irrelevant), but which don't combine to solve the problem at hand. A competent physics student would notice this and reject the AI's answer.

When you're given pressure per unit area, it's appropriate to multiply that across the affected area to get the total load. That's how you would solve a problem such as a 44 m/s wind blowing against a window of known area. The "standard formula" for fluid dynamic drag I posted some pages back works for wind loading. It can compute the unit pressure of wind of a given density blowing at a given velocity. Then you can multiply by area (ignoring C_D for now) to give the total load.

But as I pointed out, here we deal with a total force that must be divided by the contact area. That total force wasn't computed anywhere in the demonstration because the AI was confused about what was being asked for. We know it's a colossal force because it's the force required to stop a ship moving at a certain velocity in a very short distance. But at this point we don't know what it is.


Here the AI has just pulled a number out of its digital backside without any attempt to match it to the "dimensions" of MS Estonia. It's warning Vixen that it has done this, but Vixen either doesn't know what to do with that or doesn't care. Rocks poke holes in ships because even smooth rocks don't have contact areas in the thousands of square meters. The force is concentrated in a small area of the ship's hull.


This correctly computes hydrostatic pressure at a depth of 80 meters over an area of 1000 m², but as far as the problem Vixen is claiming to have demonstrated goes, it might just as well be a recipe for salad cream. It could be a thousand square meters of seabed itself, without a shipwreck in sight. And it's irrelevant in a flooded ship, where water pressure increases uniformly on everything and not in a specific direction only.

Yet this is the figure Vixen reports as the answer for how hard the MS Estonia struck the seabed. And this travesty of physics is how she imagines one would "demonstrate" that answer.


The competent physics student should have realized at this point that at no time did the solution incorporate the purported mass of the ship. It doesn't take a triple-niner intelligence to understand that a heavier ship lands with greater force than a lighter ship at the same velocity, and that therefore the mass of the ship should have affected the computation somewhere at some time. The 15,000 figure was never "plugged in" anywhere. The AI just mentions it in passing because it was input data.

And I'm pretty sure we already discussed that the 15,000 figure is the gross tonnage of the Estonia, which is a commercially-defined metric that is nonlinearly proportional to the ship's commercially useful volume. It has practically nothing to do with the mass of the ship for physics purposes. It's not proper to refer to it as a "15,000 tonne" ship because gross tonnage doesn't actually have a dimension—certainly not metric tons.


Maybe Vixen will one day understand just what kind of heavy lifting this last bit has done. Our fee to a customer for figuring out everything after the comma in that sentence starts at three figures to the left of the comma.

But how about it, @Vixen? Your "demonstration" is fractally wrong, to an extent that would get you a failing grade were you to have submitted this as homework or an exam answer. So what is it that you think you have "demonstrated" with this?

Excellent explanation, JayUtah. But it is way too long for Vixen to read. Her brain will be off chasing squirrels after the third sentence so she will never even see your concluding question, let alone attempt to answer it

 

[zooterkin]

Excellent explanation, JayUtah. But it is way too long for Vixen to read. Her brain will be off chasing squirrels after the third sentence so she will never even see your concluding question, let alone attempt to answer it

She didn't manage to answer both the questions in a simple two sentence post earlier.

 

[Myriad]

I live on the New England coast. I can show you any number of places near the mouths of bays and aside shipping channels, where seals and sea birds hang out on picturesque semi-submerged rocks that emerge at low tide. Then I'll show you the centuries-old names of those waterways, most of them involving some variation of "devil's" or "hell's," that suggest how much mariners feared (and still fear) what those smooth round rocks can do to their hulls, at any ship speed including slowly dragging at anchor.

Anyone familiar with any coastline anywhere in the world can likely do the same.

 

[JayUtah]

I live on the New England coast.
[...] what those smooth round rocks can do to their hulls, at any ship speed including slowly dragging at anchor.

Anyone familiar with any coastline anywhere in the world can likely do the same.

Or Oregon and Northern California, which is closer to me. And in the Great Lakes, where I did the bulk of my serious sailing.

For Pete's sake, the Essex was stove by a whale. They're pretty rounded and somewhat softer than rock.

 

[catsmate]

I live on the New England coast. I can show you any number of places near the mouths of bays and aside shipping channels, where seals and sea birds hang out on picturesque semi-submerged rocks that emerge at low tide. Then I'll show you the centuries-old names of those waterways, most of them involving some variation of "devil's" or "hell's," that suggest how much mariners feared (and still fear) what those smooth round rocks can do to their hulls, at any ship speed including slowly dragging at anchor.

Anyone familiar with any coastline anywhere in the world can likely do the same.

I dived a couple of times at Honda Point, which sounds pretty innocuous until you learn the other names for that part of the coast; 'Devil's Jaw', 'Destroyer Rock' et cetera.

 

[Dabop]

For Pete's sake, the Essex was stove by a whale. They're pretty rounded and somewhat softer than rock.

But 'whale' is what we called in our school when I was a kid torpedoes, so therefore as a quadruple niner, I am perfectly right in saying that a whale could easily sink a boat, but only if it hits and explodes above the waterline.....