Weird Sounds from Below

[unbusted67]

I feel dumb asking this question but whenever it is bed time in the slip we always here some really weird sounds from below the boat. It is not unlike the sound of a drizzle on the roof of a house, a sort of snap-crackle-and popping. It almost sounds like batteries boiling. Is there bait down there? Is our bottom growth complaining about the flavor of our anti-fouling? Is it monsters?

This is not a one time fluke, it happens every night all night and is clearly audible. What is it?

[Islandmike]

I have been told it is little critters feeding off the bottom of the boat, possibly shrimp. Dont know that for fact but was told that by a number of people? The first time I heard it I thought it was electrical. Everyone laughed when I asked about it, Shrimp they said. I dont hear it hear it here in Jacksonville, but it was loud and clear up in the cheasapeake.

[captain465]

How badly covered with barnacles is your hull?????? They will make a "clicking" sound.........the more there are, the more noise they make!!!!!!!!!

[Hud3]

We've heard it often, and with no barnacles on the bottom, so I'm assuming it's the tiny shrimp-like creatures enjoying the algae on the bottom.

[Portobello]

Yeah - get it too - here in Tasmania -even straight after the boat has been scrubbed - I think it is little critters on the bottom or on the piles of the wharf you are tied to doing their thing and the sound travels through the water and through the hull - clickety click!

[Tropicyachty]

Shrimp........

[speciald@ocens.]

Polyestermites, they are eating your boat. Actually, many years ago, "Motor Boating and Sailing" magazine ran an article on polyestermites in its April edition. The next month, they published all the letters sent by readers wanting to know how to protect their boat from this dreaded menace. April Fools! No, its shrimp.

[Serrano]

Snapping (also called Pistol or Clicking) Shrimp -

"The snapping shrimp competes with much larger animals, like the Sperm Whale and Beluga Whale, for the title of 'loudest animal in the sea'. The shrimp snaps a specialized claw shut to create a cavitation bubble that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. The pressure is strong enough to kill small fish.[7] It corresponds to a zero to peak pressure level of 218 decibels relative to one micropascal (dB re 1 μPa), equivalent to a zero to peak source level of 190 dB re 1 μPa at the standard reference distance of 1 m. Au and Banks measured peak to peak source levels between 185 and 190 dB re 1 μPa at 1 m, depending on the size of the claw.[8] Similar values are reported by Ferguson and Cleary.[9] The duration of the click is less than 1 millisecond."

Quoted from Wikipedia - Alpheidae - Wikipedia, the free encyclopedia

[Starbuck]

It's like trying to fall asleep in a giant bowl of Rice Krispies, and the first time you hear it can be unsettleing… but there's no harm.

[TaoJones]

Check out this thread: http://www.cruisersforum.com/forums/...und-18652.html. Here's a link to a YouTube clip:

YouTube - Pistol Shrimp

TaoJones

[unbusted67]

Originally Posted by Serrano

Snapping (also called Pistol or Clicking) Shrimp -

"The snapping shrimp competes with much larger animals, like the Sperm Whale and Beluga Whale, for the title of 'loudest animal in the sea'. The shrimp snaps a specialized claw shut to create a cavitation bubble that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. The pressure is strong enough to kill small fish.[7] It corresponds to a zero to peak pressure level of 218 decibels relative to one micropascal (dB re 1 μPa), equivalent to a zero to peak source level of 190 dB re 1 μPa at the standard reference distance of 1 m. Au and Banks measured peak to peak source levels between 185 and 190 dB re 1 μPa at 1 m, depending on the size of the claw.[8] Similar values are reported by Ferguson and Cleary.[9] The duration of the click is less than 1 millisecond."

Quoted from Wikipedia - Alpheidae - Wikipedia, the free

encyclopedia

That is totally cool and totally not what is under my boat. At 190 dB I wouldn't be getting much sleep. In fact I would be pretty deaf. I am thinking that there are a lot of shell fish that line the inside or our slip.

[Tropicyachty]

I have liveaboard in San Diego and the bay is full of snapping shrimp! That is all you are hearing!

[Serrano]

Noise is high, power is low. Would only sound really loud if you had one in your ear! Once through water and yr hull - just a sharp click. These are tiny animals making very loud micro-noises - that's why you can hear them through your hull.

[zeehag]

krill--a kind of brine shrimp!!!!

[s/v Jedi]

Wow, I agree with Zeehag!! ;-) Yes, it's krill, tiny shrimp.

cheers,
Nick.