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Old 29-11-2007, 21:30   #1
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Loud crackling beneath waterline - help!

So here's a good mystery... Our 1982 Crealock 37 is suddenly full of a crackling noise that seems to be getting louder. The sound is diffuse, i.e., not from any single identifiable location, but seems to be coming from below the waterline. We've now heard it in the last three places we've been, spread over about 300 miles, so natural underwater sounds seem unlikely - we assume it's something from our boat.

The boat is solid glass, was just in the yard for new bottom paint and zincs about 2-3 weeks before the sound started. Sounds like rice crispy treats, a constant, and pretty loud, crackling.

I'm sure you can all empathize with how crazy this will soon make us... anyone have experience with something similar???
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Old 29-11-2007, 22:10   #2
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So here's a good mystery... Our 1982 Crealock 37 is suddenly full of a crackling noise that seems to be getting louder. The sound is diffuse, i.e., not from any single identifiable location, but seems to be coming from below the waterline. We've now heard it in the last three places we've been, spread over about 300 miles, so natural underwater sounds seem unlikely - we assume it's something from our boat.

The boat is solid glass, was just in the yard for new bottom paint and zincs about 2-3 weeks before the sound started. Sounds like rice crispy treats, a constant, and pretty loud, crackling.

I'm sure you can all empathize with how crazy this will soon make us... anyone have experience with something similar???
Get used to it........it's perfectly normal. Small critters eating other smaller critters.
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Old 29-11-2007, 22:18   #3
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Get in the water when you hear it if that is possible. If it is a critter like certain species of shrimp or fish...then it will be coming from all around. If it's the boat then a haulout may be in order. I can't imagine what in heck on a boat could make that sound. I bet its critters.
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Old 29-11-2007, 22:42   #4
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Correct me if I'm wrong.......you're heading south...right?
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Old 29-11-2007, 23:08   #5
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Correct me if I'm wrong.......you're heading south...right?
South of about Monterey Bay California you will hear Popcorn Shrimp.
Wait until you get to Mexico and hear Croaker Fish!

Do I win a prize?

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Old 29-11-2007, 23:39   #6
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Yep it is the same the world over. Everything from shellfish to Barnicles to what ever else in that soup we call the Sea. The first night I tried to sleep on our boat, I thought I had just bought a nightmare. I didn't sleep a wink. I thought maybe the FC was fizzing or something. I couldn't work it out. I went straight back to the broker first thing in the morning. The guy cracked up laughing and replied, "oh I should have told you to expect that, it's just the marine life" I have heard several vesions of what actually is causing it. From shellfish like the mussels feeding, to barnicles and sprat trying to attach to the hull, and they spit themselves off because of the Anti-fouling. I dunno, but I certainly notice it is quite during the cold winter months in the marina and like Ricebubbles when you pour the milk on, during the summer.
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Old 30-11-2007, 01:02   #7
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It always sounds like cellophane crackling. I love the sound of it. Some old guy once told me it is phosphorus. Geez Alan, how do you spell that?

Off down the Sounds again tomorrow Alan. Only for the night though. We will take Max with us. Can't be bothered with the hairy fella for more than one night.
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Old 30-11-2007, 02:51   #8
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The main culprits are snapping shrimp which are found around the world in temperate and tropical waters. A google will turn up piles of info on them including audio.
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Old 30-11-2007, 06:09   #9
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Most marine invertebrates known to produce sounds do so by stridulation, or rubbing two parts of their bodies together.

The snapping shrimp, the noisiest creatures in the shallow ocean, is an exception to this.

Snapping shrimps are, capable of drowning out submarine sonar by the "snap, crackle and pop" of bubbles generated by their claws.

The enlarged claw is usually slightly opened but during muscle contraction, the claw closes at a very high speed. This causes the water to cavitate and form a bubble of vapor. The sound that is heard from the shrimp is produced upon collapse of this bubble.

Light is also produced when the bubble collapses and has been referred to as 'shrimpoluminescence' by researchers.

Goto “Snapping Shrimp” ~ By Kristin Leutwyler:
Snapping Shrimp: Scientific American

And “ScienceDaily” (Sep. 22, 2000):
Snapping Shrimp Drown Out Sonar With Bubble-Popping Trick, Described In Science
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Old 30-11-2007, 06:13   #10
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Pistol shrimp. Saw a good video of them on another site. Apparently they can stun their prey by snapping their one big claw. Here I found it on YouTube.

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Old 30-11-2007, 06:18   #11
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Wait until you hear humpbacks singing through your hull....
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Old 30-11-2007, 09:38   #12
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Some of those shrimp are amazing. Alpheidae - Wikipedia, the free encyclopedia

When they kill the little fish, the bubble hits 110,000 degrees F. My fiancee still doesn't believe me when I tell her that.
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Old 30-11-2007, 11:17   #13
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110,000 degrees F.
So it's not man causing Global warming, it's over population of these shrimp. I can see the bumber sticker now.

Reduce Global warming, catch more shrimp! ;-) :-)
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Old 30-11-2007, 14:29   #14
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My fiancee still doesn't believe me when I tell her that.
Rebel,

I don't believe you either! According to the wikipedia entry the temperature is equivalent to the surface of the sun which would be about 10,000F (impressive enough in itself!) But I am willing to be amazed. Do you have a reference for that number?

Mike
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Old 30-11-2007, 14:45   #15
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Rebel,

I don't believe you either! According to the wikipedia entry the temperature is equivalent to the surface of the sun which would be about 10,000F (impressive enough in itself!) But I am willing to be amazed. Do you have a reference for that number?

Mike
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You'll have to buy it if you want the content, but the study was published in the Journal of the Acoustical Society of America, in 1997.

The obvious question is "why isn't the water boiling then?" It's because of the size. It's the same reason that you could have a heavy metal burning at several thousand degrees, but stand 10 feet away, and be cold, not feeling any of the heat. The thermodynamics involved are still very much on the side of the ocean.

Look at it another way: All of the heat generated by man, has still never raised the temperature a single degree. I haven't really gotten into the physics of global warming, but from what I understand it's the sun having a more pronounced affect because of our gas emissions, not from any heat that we're generating.

If I'm right about that, and I don't think I'm too far off, we could never light another fire again, but dump out more geenhouse gasses, and we'd still have global warming.

So the effect of heat in such a large area, when it's *so very small*, doesn't change much.

It takes a heck of a lot of heat, over a very long amount of time, to change the temperature of water.
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