Noisy barnacles or rice crispies???

[andyorr]

Have done 4 charters in various locations in the Med now and on all 4 boats have experienced a very strange noise heard at quiet times in harbour and anchor.
It sounds like rice crispies, snap, crackle and popping away. I tried everything to locate the noise which was very loud on last weeks trip around the Saronic Gulf. I seemed to coming from very low down in the boat, possibly below the waterline or under the hull.
Could it be barnacles tap dancing over the hull, their little legs waving about????
I have never heard it on my Moody kept in the UK!
Any ideas? Puzzled of Gloucestershire.

 

[Davy_S]

Shrimps! /forums/images/graemlins/smile.gif

 

[iangrant]

standard noise in warmer climes - whatever it is is normal - time for a lift out and scrub?

 

[jimbaerselman]

No, not Red Snappers.

But shrimps. Some say, snapping their tails so quickly that it creates cavitation. More likely clicking their fingers (claws).

Good way to escape your predator? Mating call? Maybe. Wanna do a thesis?

Have a look at shrimp noise

 

[jimi]

Cos the Med is just a large enclosed pond and sound travels further but slower in water than in the air, what you are hearing is the crunch of feet on a distant shore a long time ago, perhaps even the greek feet as they oull their horse up to the gates of Troy.

 

[Kilter]

How do you "oull" a horse and is such a thing legal?

 

[jimi]

Oulling a horse

Oull is a concatenation of "oil" and "pull" some greeks would spread olive oil under the base of the horse and others would pull it. Homer was the first to use this word.

 

[Kilter]

Re: Oulling a horse

Ah very clever! Hence Homer Sapient! /forums/images/graemlins/grin.gif

 

[William_H]

Hello Jim almost right the snapper shrimps (prawns) have one over sized nipper that is snapped together to create a shock wave to stun micro sized creatures. (As i understand) The snapper prawns here are about 2cms long and very noisy at night in Swan River. olewill

 

[mobeydick]

I too have often wondered about that noise. I find it difficult to believe it is shrimps: I would imagine they did their clicking thing occasionally to catch food or whatever, but it is a continuous barrage of noise. OK there are a lot of shrimps, but even so……. Locally, I was told it was fish eating stuff off the hull (not so) noise of waves on pebbly beaches (so why not in the Solent as well?) and other opinions.

 

[BrendanS]

you can hear it here
http://www.dosits.org/gallery/inverts/2.htm

 

[steve_cronin]

Nay, yer boat\'s got an invasion of.....

Yes!

COCKROACHES!!!!


HO Ho Ho!

There was a time in the Med when a lot of charterers were told this and actually believed it. We met up with a family in Kos who were trying to make "Roach Traps" which they baited with evaporated milk on chunks of bread. I don't think that they caught any but then, once the milk had started to go off, none were brave enough to stick their heads below the floorboards to find out.

Steve Cronin

 

[oldharry]

Re: Nay, yer boat\'s got an invasion of.....

Its osmosis bubbles forming in the gel coat in all that lovely warm water..... not a problem (for you) if you have only chartered.

 

[paulwitney]

Same as O'Will - this time on the other side of OZ. Shrimp having a party under the boat. Some nights it sounds like you're walking on bubble wrap. Noisy little buggers!!!

 

[steve28]

I thought it was seaweed, maybe due to too much mouthwash

 

[johnneale]

We think its barnacles... (but we dont get barnacles off sand in Greece). Dont thinks its shrimps (as never seen them). Maybe baby crabs. My wife thinks its the boat cooling down (like central heating pipes). Or just the boat cracking up.... /forums/images/graemlins/confused.gif

 

[BrendanS]

listen to the sound file on the link I posted, and tell us how close you think it is?

 

[tcm]

shrimps

agreed it's the shrimps.

But why are they there? I*think* they are attracted to the barnacles, to eatem. Because see when boat just plopped back in the water with no barnacles - no snap crackle and pop

 

[jimbaerselman]

Re: shrimps

Shrimps, yes. The subject was investigated in great depth (groan) by the US Dept of Defence towards the end of WWII and early cold war days, because the total noise was a significant interference to underwater listening systems. Quote from an abstract:

"Crangon (Alpheus) and Synalpheus are the two principal genera of noise-producing shrimp. These animals (not to be confused with commercial shrimp, which are noiseless) are about 3/4 inch to 1-1/2 inches long. They have one enlarged claw which produces a vigorous snap when closed. Over a large colony there is a continuous succession of snaps which causes an intense crackling noise resembling the burning of dry twigs. With increasing distance from the shrimp bed, the crackle merges into a sizzle or a hiss."

The 'snap' was thought to be a mechanism for stunning nearby prey, which could then be more easily caught and eaten.

A similar system was used in WWII to capture submarines; depth charges.

 

[CelebrityScandel]

Re: shrimps

I've been told that it is possible in some places to hear snapping shrimp even from land while walking beside the water, but not heard them like that myself.

Maybe TCM's observation is due to fewer small animals attracted to the bottom of the boat, and which might be prey for the shrimps, when the boat's bottom is clean?