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Discussion Starter · #1 ·
I am out on block island in great salt pond. It is late at night and I can hear waves crashing on the town beach. Another interesting sound is the ticking. Seems to be coming through thehull from the water. I have heard this before. It is not the mooring line or ball . It comes from different directions and changes in loudness. Is it some kind of fish or bird?
 

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Wow. The Block Ness Monster. Cool. Never heard that one before.

How are the crowds in the pond? I have guests that would love to go, but I usually avoid Jul and Aug like the plague. Especially a sunny, flat sea weekend, like the one coming up.
 
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I'm headed to block as I type this...looking forward to the ticking...but I thought at first you were talking about ticketing...like by the harbor master lol.

How are the crowds right now...hoping to get a mooring then to anchor. I hope to be there by 1:00 today.
 

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The noise comes from shrimp or krill (scallops are also possible contributors). I love that noise!
Bruce
Yep, I was just about to say that. We get the same sound from the shrimp in the Mississippi Sound when we anchor. :)
 

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I feel ripped off. Been going to Block Island since I was a teenager and have never heard them.
 

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Discussion Starter · #8 ·
Wow shrimp are that loud??? That is Mazing. Not that it is exterrmly loud but it is louder than I would expect shrimp to be. It is moderately busy. No open moorings and a good amount anchored but not like fourth of July week. You will likely be anchoring first and looking for a mooring in the morning
 

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Aka Pistol Shrimp. First time we heard them, in Marina Del Rey, I was tossing aside cushions & gear: it sounded like the entire hull was delaminating. Took awhile to learn it was shrimp on the bottom, using their claw as a sonic weapon. I love that they often co-habitate with a goby. A real Felix & Oscar arrangement.
 

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Wow shrimp are that loud??? That is Mazing. Not that it is exterrmly loud but it is louder than I would expect shrimp to be. It is moderately busy. No open moorings and a good amount anchored but not like fourth of July week. You will likely be anchoring first and looking for a mooring in the morning
You have to remember that sounds conducts much, much better in water than it does in the air.

For the brainiacs: (and, yes, I cut and pasted this). :D

Sound is a vibration of kinetic energy passed from molecule to molecule. The closer the molecules are to each other and the tighter their bonds, the less time it takes for them to pass the sound to each other and the faster sound can travel. So it's easier for sound waves to go through solids than through liquids because the molecules are closer together and more tightly bonded in solids. So it's also harder for sound to pass through gases than through liquids, because gaseous molecules are farther apart. The speed of sound is faster in solid materials and slower in liquids or gases. The velocity of a sound wave is affected by two properties of matter:

(1) elastic properties
(2) density

The solution is described as

V = SQRT [ Cij / ρ ]

Where:

Cij = elastic properties
ρ = density of the medium

The speed of sound is different for different "sub-types" of solids, liquids, and gases. Why? Because the elastic properties are different for different materials. Elastic properties are the tendency of a material to maintain its shape when a force is applied to it, rather than deforming. A material like steel won't deform nearly as much as a piece of rubber under the same force. Steel is rigid with high elasticity, rubber deforms easily and is flexible.

At the particle level, a material with high elasticity (like the rigid steel) has atoms and/or molecules with strong forces of attraction for each other. These forces are like springs that control how quickly the particles return to their original positions. Particles that return to their original position quickly are therefore ready to move again more quickly, so they can vibrate at higher speeds. So steel, with a faster "rebound" conducts sound much better than the rubber. By which I mean the material, not the colloquial word for a condom.

The phase of matter is a large influence on elastic properties. In general, the bond strength between particles is strongest in solids and weakest in gases. As a result, sound waves travel faster is solids than in liquids, and faster in liquids than in gasses. While the density of a medium also affects the speed of sound, the elastic properties have a greater influence on the wave speed.

Density of the medium is the second factor that affects the speed of sound. This describes the mass of a substance per volume (as in a seawater density of 1,200 kg/m^3). A denser material has more mass in a given volume. Usually, larger molecules have more mass. If a material is denser because its molecules are larger, it will transmit sound more slowly. Sound waves are made up of kinetic energy. It takes more energy to make large molecules vibrate than it does to make smaller molecules vibrate. So sound will travel at a slower rate in the denser object with big molecules, if they have the same elastic properties. If sound waves were passed through two materials with approximately the same elastic properties such as aluminum (10 psi) and gold (10.8 psi), sound will travel about twice as fast in the aluminum than in the gold. This is because the aluminum has a density of 2.7gram per cubic cm which is less than the density of gold, which is about 19 grams per cubic cm.

One thing that always seems strange to people is that warm air transmits sound faster than cool air. Which doesn't make sense, because the molecules are apart, right? True. But the warmer air is more energetic, so its molecules are moving faster... which brings us back to the elastic properties.

So, in the end, it's not so much the density that controls the speed of sound, but the elastic properties of the material. You can plug random numbers into the equation to prove this to yourself.
 

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Mantus shrimp are very common from rhode island to cape cod. My friend has a oyster farm at Pt Judith and has traps for the shrimp. They can smash a clam or oyster. Search youtube for some videos. Pretty amazing. They're aggressive buggers!
Jim
 

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And if you are snorkeling and come across a Mantis....keep your fingers off or he will keep them. They can do some serious damage.
 

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I too have been fooled by them. To me, was like a crackling sound. I freaked, thinking it sounded like an electrical short somewhere in my boat.

Another sound that didn't belong , turned out to be mating Drum (fish). I couldn't figure out what was "groaning" on the boat.

Black drums become very noisy during the mating season. The low pitched sounds that they produce travel long distances. The males produce the sounds to attract females.

In 2005, residents in Cape Coral on the Florida Gulf Coast complained that they were being kept awake at night by low-pitched throbbing sounds in their homes, which they believed were being created by an engineering fault in the buildings. It was eventually discovered that the sounds were being created by black drum fish, which at first the residents found hard to believe. The fish had swum into the canals and estuaries in the area. Their mating calls were penetrating the ground and the seawalls and entering nearby houses. Fish That Make Sounds - Purrs, Grunts, Hums and Hoots

Ralph
 
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