Strange noises at anchor

[MM5AHO]

A thread on the reader to reader section about anchor chain noises (electrical?) reminded me of strange noises I've heard while at anchor sometimes.
Seems to be only when anchored on rocky bottoms, and only when quite still weather, and sounds like a high pitched squeaking, with a sort of watery / underwater sound. It's intermittent, and I noticed it in the cabin only, and after putting my ear on various surfaces, cavities etc note it being loudest in the hull, keel and that area. Ear on the timber that supports mast to keel, is loud too, probably conducted from keel.
From the loudness I suppose it to be an underwater noise, and I wondered which animal might make it.
Guessing, I'd say some sort of crustacean, maybe a lobster?
It doesn't come from the boat I don't think. I've heard it from the dinghy, by putting my ear on the floor (inflatable), so almost as good as putting an ear in the water.

Any ideas?

 

[oldgitofthewest]

seahorse crying for the destruction of its home

 

[Salty John]

Probably krill, a small shrimp like creature.

 

[Deleted member 36384]

Bit of a contortionist Geoff or you own a very large yacht. Sounds positively back aching.

 

[Twister_Ken]

That'll be them sirens calling you to your doom...

 

[jimbaerselman]

There has been considerable research into a continuous high pitched crackling sound from the seabeds. It interfered with submarine detection devices laid fairly comprehensively during the cold war. Often heard by yotties moored close to a concrete quay above a hard bottom.

The cause of that was a type of small shrimp. It's the noise of thousands of tiny tails being flicked, creating brief cavitation, which stuns or disorients their potential prey.

Same thing?

 

[Billjratt]

Underwater noises that I've heard vary with location!
You should hear the racket in Alicante Marina - waterline nibblers and octo-legged beaky scrapers plus every water-borne mechanical device - especially those accursed bow-thrusters.
There's got to be an argument for a boat big enough to have bunks well above the waterline.
Having said all that, I've heard staccato cracking/ticking but not a natural squeal or 'tone' of any duration.

 

[Baggywrinkle]

Definately heard the shrimps cracking and clicking in the med.

Also heard sonar through the hull in the Clyde, that scared the willies out of us - the sub surfaced about 500m away and was being hunted by a helicopter.

Actual continuous high pitched tones, nope never noticed - just low pitched hum coming from stuff when moored in a tide (boarding ladder down).

 

[Clyde_Wanderer]

Definately heard the shrimps cracking and clicking in the med.

Also heard sonar through the hull in the Clyde, that scared the willies out of us - the sub surfaced about 500m away and was being hunted by a helicopte

Reckon it was nicked by a joyrider?
C_W

 

[machurley22]

A thread on the reader to reader section about anchor chain noises (electrical?) reminded me of strange noises I've heard while at anchor sometimes.
Seems to be only when anchored on rocky bottoms, and only when quite still weather, and sounds like a high pitched squeaking, with a sort of watery / underwater sound. It's intermittent, and I noticed it in the cabin only, and after putting my ear on various surfaces, cavities etc note it being loudest in the hull, keel and that area. Ear on the timber that supports mast to keel, is loud too, probably conducted from keel.
From the loudness I suppose it to be an underwater noise, and I wondered which animal might make it.
Guessing, I'd say some sort of crustacean, maybe a lobster?
It doesn't come from the boat I don't think. I've heard it from the dinghy, by putting my ear on the floor (inflatable), so almost as good as putting an ear in the water.

Any ideas?

Any fish farms nearby?

 

[photodog]

Polyestermites.

Well known problem.

 

[MM5AHO]

Last time I heard this was in Lamlash Bay, anchored perhaps 200m from the fish farm in the south of the bay. So Salmon make a noise?

This sounded more animalistic than mechanical!

 

[machurley22]

So Salmon make a noise?

Not as far as I know but seal scarers do - a bit like electronic crickets chirping underwater.

Found the recording on this page of snapping shrimp and seal scarer in the background.

https://www.sams.ac.uk/Members/BEWI...ter-sounds/ataudio.2009-12-16.1229929395/view

My browser says there is a problem with the site's security certificate but there isn't - honest. It's the SAMS site which you'll know Geoff.