4 ms·

If you have the chance to listen to actual boat noise from an underwater microphone, you’ll be surprised at how loud it is and how far sound can travel. It’s le

If you have the chance to listen to actual boat noise from an underwater microphone, you’ll be surprised at how loud it is and how far sound can travel. It’s less of a problem with pleasure boats and more of an issue with commercial ones like container ships. Other sounds that are loud underwater and harmful for animals include wind turbine noise (from spinning giant blades) and sonar pings.

ck2 2y ago
US Navy (and certainly others) kill many dolphins, whales and other sea life with their high powered sonar. US also has high powered ultra low frequency radio (ELF) for communication to subs and that's got to be insane to wildlife. https://en.wikipedia.org/wiki/Project_Sanguine https://en.wikipedia.org/wiki/Project_Sanguine
- dingnuts 2y ago
  sound and radio are of course waves in completely different media. why would low frequency radio waves be insane to wildlife? it's not like it's microwave (which would cook them) or pressure (sound) which directly physically damages their organs. almost by definition low frequency radio waves are low energy, so I don't see how this would be more dangerous to Flipper than my Wi-Fi router is to me
  - d3w3y 2y ago
    Well, some people do think their Wi-Fi routers can hurt them ... maybe we should make tinfoil hats for the cephalopods.
  - bee_rider 2y ago
    Huh, sharks pick up EM signals, right? I wonder what they think of this stuff But just to be clear, I don’t think we should suppose it is damaging and try to ask the military to stop using it (good luck, lol). It could be worth looking into though.
    - nativeit 2y ago
      I mean, we all pick up EM signals. The frequency range is the distinction, I think.
      - bee_rider 2y ago
        Sure, but sharks use them as a sense. We all pick up photons in the sense that we can all feel the warmth of the sun on our skin, but also, it is sometimes interesting to think about how people who aren’t blind perceive light.
  - blackeyeblitzar 2y ago
    I’m talking about sound not electromagnetics. It’s like a torture for marine life to be surrounded by constant noise. Many also use sound to communicate or locate.
jeffbee 2y ago
According to this (highly interesting) paper I just read, it seems that the operating sounds of wind turbines come from the gearbox, which makes more sense to me because the blades of offshore turbines are turning very slowly. Also according to the same paper, the operating noises of offshore wind farms are probably not significant. https://www.int-res.com/articles/meps2006/309/m309p279.pdf https://www.int-res.com/articles/meps2006/309/m309p279.pdf As an aside, I love discovering a researcher with such a delightful niche. How many people are out there researching "Acoustically mediated fin whale mating"? Amazing humans.
- blackeyeblitzar 2y ago
  My experience disagrees with that claim. But I suggest an easier way to verify this, which is to just go to YouTube and look at videos of the sound produced by wind turbines on land. You will hear the distinct loud woosh sound of the actual blades and not the gearbox. Personally, I feel a lot of the academic denial around this noise issue is from people with an activist goal.
  - jeffbee 2y ago
    You seem to have missed the point of the research, which is all about underwater sound propagation.
  - bee_rider 2y ago
    YouTube videos are not very difficult to edit. If you search YouTube for “noisy windmills,” I’m sure you’ll get… something. Anyway windmills are all over the place, lots of people have had the experience of being near them. If they make too much noise, that’s a problem of course, but I think lots of people can verify the existence of non-noisy ones by virtue of having seen them in person. So, sure, loud designs should be avoided since there are perfectly good alternatives.
    - teitoklien 2y ago
      > YouTube videos are not very difficult to edit. And academic papers are not difficult to fudge up with edited fraudulent data [1]. Even Ivy League colleges are committing rampant fraud sometimes for activism sometimes just to get attention and get more papers published. It’s sad that we’re at a time where academia is as untrustworthy as random videos on YouTube. But i agree with noiseless windmills part, they should be promoted more instead of noisy ones that will discourage more clean energy initiatives. [1](https://retractionwatch.com/ https://retractionwatch.com/)
sevensor 2y ago
I'm not a fluid mechanics guy, but all that cavitation from the screws seems like preventably wasted energy, not to mention a huge source of potential surface wear.
- schiffern 2y ago
  Yes you're right. I'm surprised PBCF isn't more common. It essentially reduces swirl and cavitation in the central vortex, converting it into additional thrust while also reducing shaft torque. It's an inexpensive retrofit (payoff time <6 mo) with broad compatibility, and the swap can be done while unloading with no downtime. And yes, it reduces rudder surface erosion which is caused by cavitation. Seems like a no-brainer. Maybe folks just aren't aware of the technology? https://www.youtube.com/watch?v=a8PjWSeLUzY https://www.youtube.com/watch?v=a8PjWSeLUzY
  - _yb2s 2y ago
    Fascinating, I'm really into boating and sailing and have never heard of this- no consumer grade engines or boats that I know of have this.
  - sevensor 2y ago
    Wow, that's awesome! Looks like a big win all-around. Save money, save fuel, save wear.
- _yb2s 2y ago
  A lot of the noise is from the combustion engines themselves- exhaust often releases underwater, and the engine vibration transmits through the hull.
- dredmorbius 2y ago
  Correct on both counts. Nuclear submarines feature very large, many-bladed, specially-shaped propellers often turning very slowly to reduce both noise and wear (though more the former: stealth is key to submarine operations). Cavitation on hydraulic and steam turbines, as well as other hydraulic mechanisms, is a major source of wear and failure. Keep in mind that cavitation is equivalent to boiling, and involves both high (if localised) temperatures and extreme pressure fluctuations as cavitation bubbles form and collapse. A couple of discussions from both perspectives: <https://archive.navalsubleague.org/2012/a-century-of-american-submarine-propeller-design https://archive.navalsubleague.org/2012/a-century-of-america...> <https://www.sciencedirect.com/science/article/abs/pii/S0029801820314190 https://www.sciencedirect.com/science/article/abs/pii/S00298...> For nuclear submarines, overall efficiency isn't tremendously important, as when the sub needs to move quickly the powerplant can turn out a heck of a lot of power. Checking just now to confirm powerplant output, I'm learning that the Virginia class of hunter-killer submarines, for which both quiet operation and speed for pursuit are concerns) use pump-jet propulsors rather than traditional bladed propellers, specifically to reduce cavitation: <https://en.wikipedia.org/wiki/Virginia-class_submarine#Propulsor https://en.wikipedia.org/wiki/Virginia-class_submarine#Propu...> Top speed is in excess of 25 knots. (I suspect considerably in excess, though Powerplant is a 210 MW nuclear reactor, 280,000 HP equivalent. By contrast the Maersk E-class container-ship (largest in the world until 2012) have an 81 MW (fossil-fuel based) powerplant, 109,000 HP equivalent. The still-larger Triple-Es have two 31 MW engines (for lower total output), and the current size giant CSCL Globe 69.7 MW. <https://en.wikipedia.org/wiki/E-class_container_ship https://en.wikipedia.org/wiki/E-class_container_ship> <https://en.wikipedia.org/wiki/Triple_E-class_container_ship https://en.wikipedia.org/wiki/Triple_E-class_container_ship> <https://en.wikipedia.org/wiki/CSCL_Globe https://en.wikipedia.org/wiki/CSCL_Globe> And the fastest known military submarine seems to have been the K-222 Soviet Project 661 "Anchar", which could reach 41-45 knots (about 50 mph) submerged. The K-222 is slightly shorter than the Virginia class, and as hull-length has a strong effect on top speed (see hull speed: <https://en.wikipedia.org/wiki/Hull_speed https://en.wikipedia.org/wiki/Hull_speed>, though how this relates to submarines I'm uncertain, see also Froude number: <https://en.wikipedia.org/wiki/Froude_number https://en.wikipedia.org/wiki/Froude_number>), I suspect Virginia class boats could likely achieve similar speeds should the need exist.
dylan604 2y ago
It's one of the things that I find fascinating about Naval tech. From the sonar from each boat to the network of devices like SOSUS net[0], you have to be very good and deliberate to sneak around in the oceans. [0]https://en.wikipedia.org/wiki/SOSUS https://en.wikipedia.org/wiki/SOSUS
emilecantin 2y ago
I've done some snorkeling on coral reefs in the Bahamas, and it's crazy how far you can hear boats. Once you learn what sound they make (it's completely different underwater), you can hear one very clearly but when you pop your head up it's way off in the distance. And this is just for smaller, outboard-powered boats. I've never really had the chance to hear a big ship underwater, but my home is right by the St-Lawrence seaway (the one they talk about in the article) and when it's quiet at night I can feel the rumble they make through the ground when one passes in front of the house.
_yb2s 2y ago
Even the above water noise is awful... I am sensitive to noise, and do engineless sailing partly because the sound of motors is awful, and ruins the fun of boating for me.
- te0006 2y ago
  Try a modern electric motor. There are some really quiet ones now.
edem 2y ago
when i was a kid we often camped near a river. every morning i heard music but i couldn't identify the source. "it comes from the other side" my uncle said. that day i learned how far sound can travel in the water

ck2 2y ago

US Navy (and certainly others) kill many dolphins, whales and other sea life with their high powered sonar. US also has high powered ultra low frequency radio (ELF) for communication to subs and that's got to be insane to wildlife. https://en.wikipedia.org/wiki/Project_Sanguine https://en.wikipedia.org/wiki/Project_Sanguine

dingnuts 2y ago
sound and radio are of course waves in completely different media. why would low frequency radio waves be insane to wildlife? it's not like it's microwave (which would cook them) or pressure (sound) which directly physically damages their organs. almost by definition low frequency radio waves are low energy, so I don't see how this would be more dangerous to Flipper than my Wi-Fi router is to me
- d3w3y 2y ago
  Well, some people do think their Wi-Fi routers can hurt them ... maybe we should make tinfoil hats for the cephalopods.
- bee_rider 2y ago
  Huh, sharks pick up EM signals, right? I wonder what they think of this stuff But just to be clear, I don’t think we should suppose it is damaging and try to ask the military to stop using it (good luck, lol). It could be worth looking into though.
  - nativeit 2y ago
    I mean, we all pick up EM signals. The frequency range is the distinction, I think.
    - bee_rider 2y ago
      Sure, but sharks use them as a sense. We all pick up photons in the sense that we can all feel the warmth of the sun on our skin, but also, it is sometimes interesting to think about how people who aren’t blind perceive light.
- blackeyeblitzar 2y ago
  I’m talking about sound not electromagnetics. It’s like a torture for marine life to be surrounded by constant noise. Many also use sound to communicate or locate.

jeffbee 2y ago

According to this (highly interesting) paper I just read, it seems that the operating sounds of wind turbines come from the gearbox, which makes more sense to me because the blades of offshore turbines are turning very slowly. Also according to the same paper, the operating noises of offshore wind farms are probably not significant. https://www.int-res.com/articles/meps2006/309/m309p279.pdf https://www.int-res.com/articles/meps2006/309/m309p279.pdf As an aside, I love discovering a researcher with such a delightful niche. How many people are out there researching "Acoustically mediated fin whale mating"? Amazing humans.

blackeyeblitzar 2y ago
My experience disagrees with that claim. But I suggest an easier way to verify this, which is to just go to YouTube and look at videos of the sound produced by wind turbines on land. You will hear the distinct loud woosh sound of the actual blades and not the gearbox. Personally, I feel a lot of the academic denial around this noise issue is from people with an activist goal.
- jeffbee 2y ago
  You seem to have missed the point of the research, which is all about underwater sound propagation.
- bee_rider 2y ago
  YouTube videos are not very difficult to edit. If you search YouTube for “noisy windmills,” I’m sure you’ll get… something. Anyway windmills are all over the place, lots of people have had the experience of being near them. If they make too much noise, that’s a problem of course, but I think lots of people can verify the existence of non-noisy ones by virtue of having seen them in person. So, sure, loud designs should be avoided since there are perfectly good alternatives.
  - teitoklien 2y ago
    > YouTube videos are not very difficult to edit. And academic papers are not difficult to fudge up with edited fraudulent data [1]. Even Ivy League colleges are committing rampant fraud sometimes for activism sometimes just to get attention and get more papers published. It’s sad that we’re at a time where academia is as untrustworthy as random videos on YouTube. But i agree with noiseless windmills part, they should be promoted more instead of noisy ones that will discourage more clean energy initiatives. [1](https://retractionwatch.com/ https://retractionwatch.com/)

sevensor 2y ago

I'm not a fluid mechanics guy, but all that cavitation from the screws seems like preventably wasted energy, not to mention a huge source of potential surface wear.

schiffern 2y ago
Yes you're right. I'm surprised PBCF isn't more common. It essentially reduces swirl and cavitation in the central vortex, converting it into additional thrust while also reducing shaft torque. It's an inexpensive retrofit (payoff time <6 mo) with broad compatibility, and the swap can be done while unloading with no downtime. And yes, it reduces rudder surface erosion which is caused by cavitation. Seems like a no-brainer. Maybe folks just aren't aware of the technology? https://www.youtube.com/watch?v=a8PjWSeLUzY https://www.youtube.com/watch?v=a8PjWSeLUzY
- _yb2s 2y ago
  Fascinating, I'm really into boating and sailing and have never heard of this- no consumer grade engines or boats that I know of have this.
- sevensor 2y ago
  Wow, that's awesome! Looks like a big win all-around. Save money, save fuel, save wear.
_yb2s 2y ago
A lot of the noise is from the combustion engines themselves- exhaust often releases underwater, and the engine vibration transmits through the hull.
dredmorbius 2y ago
Correct on both counts. Nuclear submarines feature very large, many-bladed, specially-shaped propellers often turning very slowly to reduce both noise and wear (though more the former: stealth is key to submarine operations). Cavitation on hydraulic and steam turbines, as well as other hydraulic mechanisms, is a major source of wear and failure. Keep in mind that cavitation is equivalent to boiling, and involves both high (if localised) temperatures and extreme pressure fluctuations as cavitation bubbles form and collapse. A couple of discussions from both perspectives: <https://archive.navalsubleague.org/2012/a-century-of-american-submarine-propeller-design https://archive.navalsubleague.org/2012/a-century-of-america...> <https://www.sciencedirect.com/science/article/abs/pii/S0029801820314190 https://www.sciencedirect.com/science/article/abs/pii/S00298...> For nuclear submarines, overall efficiency isn't tremendously important, as when the sub needs to move quickly the powerplant can turn out a heck of a lot of power. Checking just now to confirm powerplant output, I'm learning that the Virginia class of hunter-killer submarines, for which both quiet operation and speed for pursuit are concerns) use pump-jet propulsors rather than traditional bladed propellers, specifically to reduce cavitation: <https://en.wikipedia.org/wiki/Virginia-class_submarine#Propulsor https://en.wikipedia.org/wiki/Virginia-class_submarine#Propu...> Top speed is in excess of 25 knots. (I suspect considerably in excess, though Powerplant is a 210 MW nuclear reactor, 280,000 HP equivalent. By contrast the Maersk E-class container-ship (largest in the world until 2012) have an 81 MW (fossil-fuel based) powerplant, 109,000 HP equivalent. The still-larger Triple-Es have two 31 MW engines (for lower total output), and the current size giant CSCL Globe 69.7 MW. <https://en.wikipedia.org/wiki/E-class_container_ship https://en.wikipedia.org/wiki/E-class_container_ship> <https://en.wikipedia.org/wiki/Triple_E-class_container_ship https://en.wikipedia.org/wiki/Triple_E-class_container_ship> <https://en.wikipedia.org/wiki/CSCL_Globe https://en.wikipedia.org/wiki/CSCL_Globe> And the fastest known military submarine seems to have been the K-222 Soviet Project 661 "Anchar", which could reach 41-45 knots (about 50 mph) submerged. The K-222 is slightly shorter than the Virginia class, and as hull-length has a strong effect on top speed (see hull speed: <https://en.wikipedia.org/wiki/Hull_speed https://en.wikipedia.org/wiki/Hull_speed>, though how this relates to submarines I'm uncertain, see also Froude number: <https://en.wikipedia.org/wiki/Froude_number https://en.wikipedia.org/wiki/Froude_number>), I suspect Virginia class boats could likely achieve similar speeds should the need exist.

dylan604 2y ago

It's one of the things that I find fascinating about Naval tech. From the sonar from each boat to the network of devices like SOSUS net[0], you have to be very good and deliberate to sneak around in the oceans. [0]https://en.wikipedia.org/wiki/SOSUS https://en.wikipedia.org/wiki/SOSUS

emilecantin 2y ago

I've done some snorkeling on coral reefs in the Bahamas, and it's crazy how far you can hear boats. Once you learn what sound they make (it's completely different underwater), you can hear one very clearly but when you pop your head up it's way off in the distance. And this is just for smaller, outboard-powered boats. I've never really had the chance to hear a big ship underwater, but my home is right by the St-Lawrence seaway (the one they talk about in the article) and when it's quiet at night I can feel the rumble they make through the ground when one passes in front of the house.

_yb2s 2y ago

Even the above water noise is awful... I am sensitive to noise, and do engineless sailing partly because the sound of motors is awful, and ruins the fun of boating for me.

te0006 2y ago
Try a modern electric motor. There are some really quiet ones now.

edem 2y ago

when i was a kid we often camped near a river. every morning i heard music but i couldn't identify the source. "it comes from the other side" my uncle said. that day i learned how far sound can travel in the water