What Causes Jetstream Damage on Boat Hulls?

[cayucos]

Hello. I'm new to the forum, and a non-expert trying to learn about topics for a mystery I'm writing. Hope someone can tell me if this is plausible:

Drilling equipment on the seafloor either malfunctions or is sabotaged in a way that shoots a stream of water mixed with seafloor sand upward. The "jetstream" sprays the hull of a boat passing above, causing spalling-like damage and embedding bits of sand into the hull material. Kind of like cavitation damage...

Thanks for any and all suggestions/comments!

And if this is the wrong forum for this, and anyone can point me to the right forum...thanks again.

 

[cayucos]

Anybody?

Okay, I'm thinking I'm in the wrong place.

 

[john.phillip]

Given the right conditions, this "jetstream" from a blowout, have a greater probability of sinking the overpassing boat, due to a sudden loss of buoyancy caused by the water vapor and the mixed expanding gases reaching the surface, rather than actually sand blasting the hull.

 

[cayucos]

Given the right conditions, this "jetstream" from a blowout, have a greater probability of sinking the overpassing boat, due to a sudden loss of buoyancy caused by the water vapor and the mixed expanding gases reaching the surface, rather than actually sand blasting the hull.

Appreciate the reply!

I just might use such a scenario for the story climax.

But if I could mine your expertise a bit further...the scene I'm wrestling with comes at the start of the book, in effect setting up a mystery at sea. I'm not wedded to the drilling mechanism--just casting about.

I'll explain my plot need a bit more (was trying not to bore people with TMI). There is an experiment, sited on the seafloor or perhaps on the summit of a seamount, and the bad guy sabotages the experiment, and certain mayhem ensues. Part of that mayhem is some mechanism that shoots water/gas/something to the surface and--most important--this mechanism must transport bits of seafloor/seamount sand to become embedded in the hull.

Is there anything that might work? I'd thought of gas bubbles but don't know if/how they would bring along bits of sand.

My protagonist is a geologist. So in the scene, she's examining the hull of this boat and wondering what the hell is going on out there. And then her job is to analyze and track that sand (or soil) to the site, to find out what's going on.

Thanks for any help you can give.

 

[Q_Goest]

I seem to remember watching a show a few years ago that looked at the possibility of a large gas release causing a ship to sink. The contention was that a large enough gas release with bubbles dispersed sufficiently through the water, might significantly reduce the water's density. Per Archimedes principal, if the reduction in water density is sufficient, the water would no longer be able to support the ship. They actually showed an example of this using a model boat that sank when they released a large number of small bubbles beneath it.

And don't forget the http://en.wikipedia.org/wiki/Lake_Nyos" disaster in Africa in which carbon dioxide gas was released and came up to the surface, killing a huge number of people through asphixiation. The above two stories aren't linked but they could be in a sci-fi story.

As for entraining sand, I don't know how that might happen but I suppose if it's just a fictional story, ...

 

[cayucos]

I seem to remember watching a show a few years ago that looked at the possibility of a large gas release causing a ship to sink. The contention was that a large enough gas release with bubbles dispersed sufficiently through the water, might significantly reduce the water's density. Per Archimedes principal, if the reduction in water density is sufficient, the water would no longer be able to support the ship. They actually showed an example of this using a model boat that sank when they released a large number of small bubbles beneath it.

And don't forget the http://en.wikipedia.org/wiki/Lake_Nyos" disaster in Africa in which carbon dioxide gas was released and came up to the surface, killing a huge number of people through asphixiation. The above two stories aren't linked but they could be in a sci-fi story.

As for entraining sand, I don't know how that might happen but I suppose if it's just a fictional story, ...

Thanks for these. I've been reading a bit about this gas-sinks-ship issue.

My story isn't science-fiction. Strictly mystery/suspense. I don't mind stretching the science, as long as it's within the realm of possibility. Since I'm not a scientist (and didn't stay at a Holiday Inn last night ;) I'm coming here and bugging real scientists for help.

Sigh, really do need to embed that sand in that boat hull.

 

[Mech_Engineer]

Unfortunately an underwater explosion wouldn't be able to send a jet of sand fast enough to embed it in a ship's hull, although it might cause some interesting surface effects (ever seee video of a depth charge going off?). I can think a few possibilities to help solve your plot troubles:

- Dead fish on the surface due to an underwater explosion
- Fishing trawler comes up with debris (maybe the debris even has sand embedded in it, if it was part of the explosion).
- Chemicals pursuant to a problem are detected by a sea life monitoring group.

Any of those ideas "float your boat"?

 

[Mech_Engineer]

Additionally, debris could float to the surface which has specific sand embedded in it due to the explosion... as long as it's buoyant debris

 

[cayucos]

Unfortunately an undwerwater explosion wouldn't be able to send a jet of sand fast enough to embed it in a ship's hull, although it might cause some interesting surface effects (ever seee video of a depth charge going off?). I can think a few possibilities to help solve your plot troubles:

- Dead fish on the surface due to an underwater explosion
- Fishing trawler comes up with debris (maybe the debris even has sand embedded in it, if it was part of the explosion).
- Chemicals pursuant to a problem are detected by a sea life monitoring group.

Any of those ideas "float your boat"?

Hmmm, interesting ideas all. Might float my boat, or at least launch it. Thanks!

Unfortunately I've already written half the book around this plot twist, of having this experiment sabotaged and some kind of ...something... "hosing up" water/gas/bubbles to the surface, carrying bits of sand. Maybe some underwater vacuum/hose/pipe thingy that comes loose.

I sure am learning my lesson, though. Don't put off the research before writing the story.

 

[cayucos]

Additionally, debris could float to the surface which has specific sand embedded in it due to the explosion... as long as it's buoyant debris

Okay, could that debris, carrying sand, be propelled to the surface with enough pressure/force to do some cavitation-like damage to the boat hull?

I'm stuck with the boat adrift, damaged hull, as the precipitating event.

Other things from the sabotaged experiment come into play, later. In fact, one thing is a buoy released during the sabotage. So your "buoyant debris" is indeed a cool part of the story!

 

[Mech_Engineer]

Okay, could that debris, carrying sand, be propelled to the surface with enough pressure/force to do some cavitation-like damage to the boat hull?

I don't know about cavitation, but a large buoy (especailly a metal one) released from underwater could rise to the surface at a pretty good speed. If this rising boyant object collided with the ship, it could cause some damage (if it was a fiberglass hulled ship, it could rip it in half).

 

[cayucos]

I don't know about cavitation, but a large buoy (especailly a metal one) released from underwater could rise to the surface at a pretty good speed. If this rising boyant object collided with the ship, it could cause some damage (if it was a fiberglass hulled ship, it could rip it in half).

You know, that might just be a workable alternative. So, this big buoy maybe scrapes the hull of my boat, and that embeds the sand. Meaning, the buoy itself has to have the sand on its surface somewhere.

Thanks for brainstorming this.

This plot's been trying to kill me.

 

[Mech_Engineer]

You know, that might just be a workable alternative. So, this big buoy maybe scrapes the hull of my boat, and that embeds the sand. Meaning, the buoy itself has to have the sand on its surface somewhere.

Thanks for brainstorming this.

This plot's been trying to kill me.

It doesn't have to be a buoy either (why would a buoy be stored underwater?), it could be some sort of gas chamber that breaks free in the explosion and rises to the surface at a fast enough rate to surprise the boat and impact with the hull.

Of course the question is, why bother looking at the sand in the hull in the first place, it's obvious what happened and where it happened...

 

[AlephZero]

At risk of complcating the plot some more, it could be a personal underwater craft going out of control (as a result of the underwater explosion) and hitting the boat hull. These things are real: http://www.deepflight.com

I heard an interview with the deepflight designers a while ago. One of the comments was that "flying underwater is a lot more forgiving that flying in air. If you stall an airplane and can't recover normal flight, you hit the ground hard. If you stall underwater and can't recover, you just sit back and enjoy the rollercoaster ride till you reach the surface." Unless you get unlucky and hit the back side of a boat, of course.

The "deepflight" might have an external arm (for collecting seabed samples) still deployed, causing more damage to the boat hull - and even bringing up some sand from the sea bed, if you insist.

 

[cayucos]

It doesn't have to be a buoy either (why would a buoy be stored underwater?), it could be some sort of gas chamber that breaks free in the explosion and rises to the surface at a fast enough rate to surprise the boat and impact with the hull.

Of course the question is, why bother looking at the sand in the hull in the first place, it's obvious what happened and where it happened...

Point taken about the object. Thanks. I still need to figure the experiment in more detail, and hopefully that will give me some ideas about what thingy might break free.

Actually, the experiment and its site are not known. Kind of a need-to-know govt contract, meaning it's a mystery to most people in the area. In fact, when my geologist is called into track the sand, the goal is to find out what happened to the boat and its owner, a fisherman, who is missing.

 

[cayucos]

At risk of complcating the plot some more, it could be a personal underwater craft going out of control (as a result of the underwater explosion) and hitting the boat hull. These things are real: http://www.deepflight.com

I heard an interview with the deepflight designers a while ago. One of the comments was that "flying underwater is a lot more forgiving that flying in air. If you stall an airplane and can't recover normal flight, you hit the ground hard. If you stall underwater and can't recover, you just sit back and enjoy the rollercoaster ride till you reach the surface." Unless you get unlucky and hit the back side of a boat, of course.

The "deepflight" might have an external arm (for collecting seabed samples) still deployed, causing more damage to the boat hull - and even bringing up some sand from the sea bed, if you insist.

Wow, another intriguing suggestion. I'll have a look at that link. thanks. The plot thickens...

And, yes, I do insist on the sand. She is a geologist, after all. :)

 

[cayucos]

Thanks to all who have posted with ideas/advice. I really appreciate it.

I've come up with a scenario I hope will work and would sure like to run it past y'all.

There's an experiment sited on the summit of a seamount. Summit is about 100 feet below the sea surface. Experiment equipment includes a pressurized container of gas/liquid. Bad guy sabotages the equipment. That causes an attached nozzle to shoot a pressurized stream outward, entraining some seamount sand on the way upward to the surface. There, impacting the hull of my boat.

I'm guessing it's a matter of pressure/force. One more subject area in which I'm not expert. And googling gets me only so far.

Is this scenario at all plausible?

 

[Mech_Engineer]

I personally don't feel like a jet of water would be able to travel fast enough through 100 ft of water to embed sand in a boat's hull, but I don't think the scenario is too far outside the realm of possibility to allow some writer's perogative Some oil drilling rigs operate at some really fantastic pressures, so who's to say some equipment like that wasn't used...

I'm still preferential to the piece of floating sea junk, but that's just me...

 

[cayucos]

I personally don't feel like a jet of water would be able to travel fast enough through 100 ft of water to embed sand in a boat's hull, but I don't think the scenario is too far outside the realm of possibility to allow some writer's perogative Some oil drilling rigs operate at some really fantastic pressures, so who's to say some equipment like that wasn't used...

I'm still preferential to the piece of floating sea junk, but that's just me...

Well, to at least edge up to the realm of possibility... Let's say the pressurized tank on the seamount summit has a hose attached--a means for filling the tank from a ship. So then, when bad guy does sabotage, the hose becomes pressurized and takes the gas/liquid to the surface? Or maybe a pipe. I can get my seamount summit to within, say, sixty feet of the surface.

Meanwhile, I'm putting that sea junk into my alternatives file!

Thanks for taking the time to brainstorm this.

 

[Mech_Engineer]

Well, to at least edge up to the realm of possibility... Let's say the pressurized tank on the seamount summit has a hose attached--a means for filling the tank from a ship. So then, when bad guy does sabotage, the hose becomes pressurized and takes the gas/liquid to the surface? Or maybe a pipe. I can get my seamount summit to within, say, sixty feet of the surface.

Meanwhile, I'm putting that sea junk into my alternatives file!

Thanks for taking the time to brainstorm this.

I would leave the seamount 100-150ft under the surface, and just leave the story as-is: the tank explodes and sends a jet of water that embeds sand in the boat. Keep in mind a jet of water rushing fast enough to embed sand in the hull of a ship will be hard to miss- it will be more powerful than a fire hose at point blank range!

 

[AlephZero]

The problem with the physics of the water-jet idea is that if you start with a small high speed jet 100 ft down, what would happen is that the jet effectively "sucks in" the water it is moving through, and gets bigger and moves slower. If you had a large jet at the sea floor, say 1 ft diameter, after 100 feet it would have grown to about 10 to 20 feet diameter and the water would be traveling at least 100 times slower than when it left the sea bed.

If the water jet was traveling fast enough to sand-blast the boat hull, it would also be shooting several hundred feet into the air. In fact it would probably capsize the boat and sink it, not just damange the hull.

 

[Mech_Engineer]

The problem with the physics of the water-jet idea is that if you start with a small high speed jet 100 ft down, what would happen is that the jet effectively "sucks in" the water it is moving through, and gets bigger and moves slower. If you had a large jet at the sea floor, say 1 ft diameter, after 100 feet it would have grown to about 10 to 20 feet diameter and the water would be traveling at least 100 times slower than when it left the sea bed.

If the water jet was traveling fast enough to sand-blast the boat hull, it would also be shooting several hundred feet into the air. In fact it would probably capsize the boat and sink it, not just damange the hull.

All of that is kind of what I was thinking too... that's kind of why I was leaning towards some sort of floating debris. Problem is, I think his plot is based on a small clue (embedded sand being found on a boats hull) which helps narrow down the location of an event. If you collide with a big piece of debris, it's pretty obvious where it happened!

 

[cayucos]

I would leave the seamount 100-150ft under the surface, and just leave the story as-is: the tank explodes and sends a jet of water that embeds sand in the boat. Keep in mind a jet of water rushing fast enough to embed sand in the hull of a ship will be hard to miss- it will be more powerful than a fire hose at point blank range!

Okay, sounds as though I'm close enough to make it work. As long as some knowledgeable engineer wouldn't stop reading and hurl the book across the room ;)

Thanks.

 

[cayucos]

The problem with the physics of the water-jet idea is that if you start with a small high speed jet 100 ft down, what would happen is that the jet effectively "sucks in" the water it is moving through, and gets bigger and moves slower. If you had a large jet at the sea floor, say 1 ft diameter, after 100 feet it would have grown to about 10 to 20 feet diameter and the water would be traveling at least 100 times slower than when it left the sea bed.

If the water jet was traveling fast enough to sand-blast the boat hull, it would also be shooting several hundred feet into the air. In fact it would probably capsize the boat and sink it, not just damange the hull.

Oh dear. Now I'm back in trouble. But what if the water (or gas) was propelled through a hose or a pipe (to the surface, or nearly so)? Then it couldn't "suck in" the surrounding water and grow into an elephantine blob. Yes? No?

Also, doesn't have to sandblast the entire hull. Just a few lesions with a sprinkling of sand will do it for the plot.

All of that is kind of what I was thinking too... that's kind of why I was leaning towards some sort of floating debris. Problem is, I think his plot is based on a small clue (embedded sand being found on a boats hull) which helps narrow down the location of an event. If you collide with a big piece of debris, it's pretty obvious where it happened!

Yes, you're right about the "small clue." All I need is--as I said above--a few damaged spots with a little bit of sand embedded. My geologist is a whiz; all she needs is a few grains to follow!

Oh, and it's "her" plot. I'm a she. :)

 

[AlephZero]

Also, doesn't have to sandblast the entire hull. Just a few lesions with a sprinkling of sand will do it for the plot.
...
My geologist is a whiz; all she needs is a few grains to follow!

The boat could be old and scruffy, with seaweed and barnacles on the hull. Then you would pick up some type of chemical pollution (not necessarily sand) from the water, whatever the scenario was. In fact "why have the barnacles gone a funny colour" might be the first clue that something was amiss...

 

[Q_Goest]

How about a naturally formed supercavitating torpedo

propelled by a natural formation of frozen, methane ice.

Now go over to the biology forum and find out how some oxygen producing bacteria produced a large enough bubble to completely burn a large chunk of this methane ice. As the block ignited, it propelled itself and also created a 'bubble' of gas at the leading edge, creating a naturally formed supercavitating topedo!

 

[cayucos]

The boat could be old and scruffy, with seaweed and barnacles on the hull. Then you would pick up some type of chemical pollution (not necessarily sand) from the water, whatever the scenario was. In fact "why have the barnacles gone a funny colour" might be the first clue that something was amiss...

Mmmmm, that's a thought. I do need the sand clue to lead the geologist, eventually, to the site of the experiment, so as long as the pollution was localized enough, meaning coming up from the seamount experiment, could work.

I also wonder if this might help along my 'jetstream' issue. That is, how to get a strong enough high-pressure stream of water/gas to embed the sand into the hull. But with a scrofulous boat, wouldn't need as much force to attach the sand. Right? (and do like the odd-colored barnacles)

Also, FWIW, the material doesn't have to be sand. Could be clay particles, etc--as long as it's Earth material necessitating the expertise of my geologist.

 

[cayucos]

How about a naturally formed supercavitating torpedo

propelled by a natural formation of frozen, methane ice.

Now go over to the biology forum and find out how some oxygen producing bacteria produced a large enough bubble to completely burn a large chunk of this methane ice. As the block ignited, it propelled itself and also created a 'bubble' of gas at the leading edge, creating a naturally formed supercavitating topedo!

Oooh, that sounds intriguing. I'll go check it out. Thanks!

 

[cayucos]

How about a naturally formed supercavitating torpedo

propelled by a natural formation of frozen, methane ice.

Now go over to the biology forum and find out how some oxygen producing bacteria produced a large enough bubble to completely burn a large chunk of this methane ice. As the block ignited, it propelled itself and also created a 'bubble' of gas at the leading edge, creating a naturally formed supercavitating topedo!

Hey, I tried to find the thread/post you're referring to, and failed. Could you provide a link?

 

[Q_Goest]

Hey, I tried to find the thread/post you're referring to, and failed. Could you provide a link?

I just grabbed pictures from a random web site.
http://www.orbitalvector.com/Aquatic/Supercav%20Torpedo/SUPERCAVITATING%20TORPEDO.htm

http://news.bbc.co.uk/2/hi/science/nature/3775181.stm

I'd suggest just googling "supercavitating torpedo" and "methane ice".

 

[cayucos]

I just grabbed pictures from a random web site.
http://www.orbitalvector.com/Aquatic/Supercav%20Torpedo/SUPERCAVITATING%20TORPEDO.htm

http://news.bbc.co.uk/2/hi/science/nature/3775181.stm

I'd suggest just googling "supercavitating torpedo" and "methane ice".

Ah, thanks! I'll check the sites you mention first, and then google.