Strange hull noise

[ailsaboat]

After a launching my new to me old steel boat I have a strange noise!!
While sitting in the marina I can hear a loud crackling – like lots of bowls of rice crispies around the hull.
At first I was convinced that my hull was fizzing with major electrolysis, but I can’t find any signs.
I don’t have any form of shore power, in desperation I have removed the batteries, so it can't be current leakage.
During the refit I made sure all dissimilar metals were isolated.
There are no external signs around the hull, can’t see any bubbles, any visible anodes appear okay – with the amount of noise I would expect them to be boiling.

It has been suggested that it is a form of crustacean communicating???? But the boats around me (all plastic) don’t hear it.

Is this feasible, would grp insolate the sound? Or is there another possibility??

 

[webcraft]

We have had this a lot in some places in the Canaries, most noticeably in El Hierro and La Graciosa, boith of which are marine reserves full of sea life.

(Our boat is GRP)

I think it might be fish or other organisms eating the slime off the bottom of the boat - maybe all your neighbours have clean bottoms?

 

[BrendanS]

Snapping Shrimp, you can hear a recording of their sound here
http://www.dosits.org/gallery/inverts/2.htm

 

[Billjratt]

If you've just launched, the underwater people shouldn't have anything to munch on yet. However if you're new to the boat you may not yet be used to the underwater sounds it amplifies.
It may be that you get a quieter time away from other boats in a lonely anchorage somewhere.
However, fish, octopii and others do make a h3ll of a racket once they start on barnacles and other "white" bits.

 

[ailsaboat]

THAT'S IT!!!!
Thanks BrendonS
Snapping shrimp, I would never have believed it!!
Using my tinny laptop speakers, your link on full volume is what it sounds like in my boat.
Thanks a million, I can start putting all the electrical stuff back on.

 

[firstascent2002]

I had an awful night on a bareboat charter in croatia. Third night of honeymoon in a fantastic ancorage. Only boat there. I was up and down all night. Isolating gas bottles and disconecting them and water tanks left right and centre. I could not for the life of me work out what was wrong with the bloody bendy toy. Shrimps eh....

 

[sarabande]

Some people will use any excuse for being up and down all night.... /forums/images/graemlins/grin.gif

 

[ytd]

having owned both steel and GRP boats, the volume in steel boats is much louder than GRP ones

 

[EASLOOP]

As an aside, I had a similar experience with my wooden sloop moored in the Medway. On deck, no noise, below decks a whirring noise. On deck quiet etc etc. Unplugged anything that could have been making a whirring sound. Eventually tracked it down to the noise made by the screws of small boats moving around. The hull of my boat, stripped bare for refurb, was acting like an acoustic amplifier. DUH! /forums/images/graemlins/confused.gif

 

[MYStargazer]

I love this site!!!!!!!

I was having all sorts of visions of my shafts dissolving - that's exactly what I was hearing.

GRP boat - Palma de Mallorca.

Thank you. Thank you. Thank you.

 

[barnaclephill]

[ QUOTE ]
I can hear a loud crackling – like lots of bowls of rice crispies around the hull.
At first I was convinced that my hull was fizzing with major electrolysis, but I can’t find any signs. Is this feasible, would grp insolate the sound? Or is there another possibility??

[/ QUOTE ]

I listened to the snapping shrimp MP3 link here. What I've heard is a slower & louder snapping sound. I think they're mussels in the sand under the boat. In some areas there's lots of mussels, in others, hardly any, so no sounds.

I did confirm it and it seems that concrete boats hear the same noise. They were suggested that it was cracking in the concrete, but it's the same as I hear.