Help with Electrolysis

[loggerhead]

Help needed!
We are currently cruising in my five year old Sunfast 37. I have equipped her well and have added all sorts of gear. Whilst in the Canaries a few months ago we heard a popping sound coming from the hull. We emptied the boat trying to discover its source, I even swam underneath and so am convinced it was the hull making the noise. I suspected electrolysis. We did not hear the noise after leaving the Canaries but when lifted out to antifoul in Cape Town I noticed a few small holes in the gelcoat below the waterline. We have just arrived in Port Elizabeth and the popping noise has started again. It does not matter whether the batteries are on or off, or shore power connected or not. I have two Dynaplates as earths for my SSB, I noticed that the bolts securing them were badly corroded. I have not been able to find anyone with a solution. Any idea’s Please?

 

[Foxy]

Aside from any potential electrolysis issues - which I don't believe (ha.... fool! I can hear people saying) can make a noise as its just one metal corroding and and another being coated - I wouldn't become too obsessed with thinking that the noise is coming from the hull - the whole thing is pretty much a soundbox for all sorts of other bits in the boat that could be making this noise.
Have you had a thorough look through all other systems?
Is anything else not working or been troublesome?
How often does the noise occur?
Is it fwd or aft?
Is it loud or metallic?
Can you make a similar noise by doing anything else?
I know this might sound a bit daft, but certain fish can make a sort of 'tinkling' or 'popping' noise as they eat growth from your hull, especially as they rasp off shellfish etc.

Someone else here will be better placed to tell you whether there is a condition that can occur that causes these holes in the gelcoat to appear. Can you describe them more?

Lots of things to check but more info needed I think.

Cheers

Patrick

 

[Deleted member 478]

I'll 2nd the fish theory.

 

[oxman]

Interesting - we heard the same sort of thing moored off Itchenor (Chichester Harbour) twice last year.

- it appeared to happen as the tide changed and I was also worried what it could be, however, having had a quick drink I figured it must be something to do with fish or weed! - (you hear a very similar sound when diving on a coral reef)

As previously commented - if its intermittant then its unlikely to be a problem from onboard.

 

[KellysEye]

Our boat is steel and we also hear popping noises. It doesn't happen everywhere but is prevalent in certain places, for example St Lucia. Fish do make that sound but in St Lucia it's small shrimps. Seems unlikely that the noises are related to the corrosin and gelcoat issues, which are probably also separate. Gelcoat, failing? Corrosion, low quality bolts? Difficult to say without seeing it.

 

[lenseman]

I will go with the fish theory (it could of course be a Loggerhead Turtle /forums/images/graemlins/grin.gif).

When you hear it next time and the sound remains constant whilst inside the cabin, jump over the side, swim around and get your partner to note whether the noises stop all of a sudden. If so, its fish . . . . or that turtle I mentioned earlier? /forums/images/graemlins/grin.gif

 

[Bilgediver]

This is probably shrimp/prawns and has been discussed many times on these forums

See Here

 

[capnsensible]

Shrimps......I too have had a boat in bits the first time I heard them!!!!!

 

[roly_voya]

The distance that noise travels underwater can throw you. I remember on a couple of occasions hearing very lound propeller noises suddenly start and leaping on deck convinced that I was about to be run down to find all quite. I eventually twigged it was the bow thrusters on the irish ferry starting up as she manovered out ofher berth. The ferry was over 2 miles away out of sight and round a corner but below sounded like it was next door.

 

[Bejasus]

Snapping Shrimp, we have them all the time here in Georgia and in the gulf waters. Bothered the crap out of me until I found out what it was. They have one big claw which they can snap shut to either stun pery or scare predators. It itsn't the snapping of the claws together that makes the sound, it is the force of the water being compressed between the claw that does it.

 

[Grehan]

Yes, the most amazing thing. Worried us too (what on earth is it?, we wondered), most noticeable when anchored up in Torrevieja harbour. Shrimps!

 

[loggerhead]

Thanks for the comment, I do wish to refer to my comment that I swam under the boat in the Canaries, There were no fish or shrimps present, I could hear the popping loudest when my ear was next to the hull. I would be delighted if it was fish.

 

[Grehan]

I doubt you'd actually be able to see the little beasties.

 

[loggerhead]

I have just moved to East London, the "popping" noise started as soon as we were moored alongside another yacht. The noise is always constant, i.e.the amount of popping is always the same.

 

[captainslarty]

Again, yes on the fish theory !.. Mullet are a great source of unusual noises..

As for the couple of blisters, fill them with epoxy filler and forget them..

Joe

 

[lenseman]

[ QUOTE ]
I have just moved to East London, the "popping" noise started as soon as we were moored alongside another yacht. The noise is always constant, i.e.the amount of popping is always the same.

[/ QUOTE ]
If you don't want to believe the fish/shrimp snapping theories, then it must be down to the osmosis bubbles bursting and popping on the adjacent boat. Move on quickly as it is a contagious disease. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif