paul
regular
Reged: 30/05/2001
Posts: 72
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For some time now I've heard a noise which sounds like a fire crackling or rice crispies popping under my hull. As I don't seem to have a fire nor do I have any rice crispies on board it must be something else. Any ideas?
thanks
Paul
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WindFinder
regular
Reged: 03/03/2008
Posts: 291
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Quote:
For some time now I've heard a noise which sounds like a fire crackling or rice crispies popping under my hull. As I don't seem to have a fire nor do I have any rice crispies on board it must be something else. Any ideas?
Nothing relevant to offer but I recently read a book on the Mary Celeste and the one theory on what happened (in fact there was far moe evidence for what happened than I ever realized - suspect the evidence was omitted from accounts to make it seem more interesting and mysterious) is that the swelling timber cargo (packed frozen IIRC) cracked and sounded just like a fire burning. Indeed it wouldn't have been the only ship to be abandoned for exactly that reason.
I appreciate this is of no help at all but it's kind of relevant to your post and I've typed it out now so I'm hitting the button anyway!
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david_bagshaw
regular
Reged: 05/06/2001
Posts: 910
Loc: UK
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Prawns or other marine life feeding?
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David
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Silkie
regular
Reged: 19/01/2004
Posts: 1665
Loc: Scotland
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Snapping shrimp perhaps?
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Sleep after toyle, port after stormie seas.
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cliff
regular
Reged: 15/04/2004
Posts: 5838
Loc: various
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Sounds like Polymites in a feeding frenzy just before their breeding cycle. Best have your boat lifted and treated for polymites as if left untreated these little creatures can and will chew their way through FRP. They particularily like polyester based GRP but are also known to chew epoxy. You should also tell the owners of the boats moored around you that you are infected so they can have their boats treated as well and in the meantime fly flag "D" to warn other boats to stay clear.   
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 Artificial Intelligence is no match for Natural Stupidity
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dave1234
regular
Reged: 06/09/2007
Posts: 197
Loc: brisbane australia
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hi when did you last clean it ??? if you got shells and normal growth on bottom its the little crechers moveing round and feeding, but not on your structure, it is normal , if you need cleaning then thats what it is dave
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jimbaerselman
regular
Reged: 18/04/2006
Posts: 1760
Loc: Greece in Summer, Southampton ...
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Agreed, snapping shrimps. There was considerable research on this subject by the US Navy during the cold war, because the background noise created interfered with sonar detection.
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Jim Baerselman
http://www.jimbaerselman.f2s.com/ or Google 'jimb sail'
Compares the Cruising areas of Europe
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Jimmysbuildingaboat
regular
Reged: 13/11/2005
Posts: 691
Loc: Landlocked in the Midlands
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Had the same thing on a SunSail boat in Greece years ago. We had no idea what it was and even wondered if it was some kind of leak.
SS imediately said 'It's fish feeding off the hull'
You wouldn't think they'd like rice crispies would you?
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My Big Boat-Building Blog www.sailtales.co.uk
Pull up a chair and catch up with your
Marina Mates
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VicS
regular
Reged: 13/07/2002
Posts: 9696
Loc: Home: Kent. Boat: Chichester
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Quote:
snapping shrimps. ................... during the cold war,
Just hope its not buster crabs!
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Old Chemists never die, they just fail to react
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bilbobaggins
regular
Reged: 12/02/2005
Posts: 7375
Loc: The Shire
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"The old 'uns are the best 'uns....?"
Clearly a fan of the Sainted Des!
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"See yoo, jimmy!"
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PuffTheMagicDragon
regular
Reged: 16/05/2001
Posts: 2875
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Fish grazing on the bottom growth. Scared the 'stuff' out of me when I first heard it during the first night that I slept on board an old Vivacity that I had. My ear was only a couple of inches away. First reaction was "Gribble!" before I remembered that it was a GRP hull. 
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NealB
regular
Reged: 19/02/2006
Posts: 545
Loc: UK: Devon and London.
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[Clearly a fan of the Sainted Des!
I'm going to both show my age, and reveal a horrible streak of pedantry, but, credit where credit's due: I think it was the late, great Bill Beavis (rather than the late, great Des Sleightholme) who dreamed up the polyestermite in 'Looking around' as a YM April fool too many decades ago.
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Bejasus
regular
Reged: 09/06/2002
Posts: 5697
Loc: Savannah 32 00.50N - 80 59.90W
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dunno how many times I have posted this now, but it will indeed be snapping shrimp
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'Bejasus'
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dunedin
regular
Reged: 03/02/2004
Posts: 150
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Interesting. We heard a similar sound on a charter boat in the Hauraki Gulf. Was a bit disconcerting at first, sounded like some form of electrical fault, but came from underneath.
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Clifford_Pope
regular
Reged: 28/10/2005
Posts: 788
Loc: Pembrokeshire
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It's the pack ice tightening its grip. Best load stores onto the sledges and prepare for a long haul.
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oldharry
regular
Reged: 30/05/2001
Posts: 3941
Loc: North from the Nab about 10 mi...
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Its the dreaded Osmosis bubbles forming in the gel coat, and cracking into the GRP.
First heard it 50 years ago in my old Lysander..... 
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If you cant fix it, get a bigger hammer...
Edited by oldharry (19/05/2008 09:07)
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mawm
regular
Reged: 24/04/2007
Posts: 38
Loc: Auckland
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I agree with Cliff - Polymites. If left untreated they will sink your boat. They are not hard to get rid of, but you do need a special polymite spray to apply to your boat. This can be done easily by you while your boat is safely moored.
5 Gal will cost only $100 - that is enough to do your average 32 footer. I can be contacted at
underwaterspray@Ship'o'fools.com
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sighmoon
regular
Reged: 06/02/2006
Posts: 595
Loc: Doha
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We had the same thing on a charter boat in Greece. I thought it sounded like soap bubbles popping. Charter co said it was barnacles dying off because of the antifouling.
Personaly though, I've decided it was sand drifting past in the current. I heard something similar much later while snorkeling - and I'm sure it was sand that time because I saw lots of it.
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Sailfree
regular
Reged: 18/01/2003
Posts: 2880
Loc: Solent
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Quote:
I've decided it was sand drifting past in the current.
Is there much of a current in Greece?
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sighmoon
regular
Reged: 06/02/2006
Posts: 595
Loc: Doha
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No, there isn't. The snorkeling was somewhere else, but it sounded much the same.
We only heard the sound at night, so I wonder if there's a bit of a convection fed current, as surface water cools, and the water that was at the bottom rises, bringing sand with it.
Of course I really don't know, but I think that sounds convincing.
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Twister_Ken
regular
Reged: 31/05/2001
Posts: 15055
Loc: k, stock & barrel.
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Corrosion getting at the keel bolts, surely.
Oh, you've got a multihull?
Then it'll be corrosion in the crossbeams
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If, at first, you don't succeed...
...don't try sky diving.
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Silver_Fox
regular
Reged: 03/04/2006
Posts: 378
Loc: Cruising Tunisia
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Funny you should mention that because I spent 2 hours one night, when at anchor looking in every locker and space because I convinced myself that the crackling noise could be the start of an electrical fire!
Needless to say it wasn't, and as I also hear it in very calm conditions I am pretty convinced its nothing structural, so like others, I have concluded its "something" feeding!
Time for the medication nurse.
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Eagles may soar......but foxes don't get sucked into jet engines
http://Yacht.silverfox.googlepages.com
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