Strange Noise from SO42i

[nigelhopkins]

So we've had 3 days on out 2010 Sun Odyssey 42i and still trying to get used to some of the unique noises the boat makes. In the night there's one really strange noise. It is similar to the sound an empty bottle would make if you pushed it underwater in a sink. The kind of 'burble/gurgle' of air in water. It would happen 3 or 4 times then stop and then start again randomly a few minutes later. Sometimes it would happen 3 or 4 times, then maybe once and then twice etc. 

Could it be, Air escaping from the vents to the holding tanks?

It seemed to happen in the early hours when a) I was too tired to move and b) it's difficult to be sure where the noise is coming from.

Any ideas or experience of this would be appreciated.

[NZL50505]

Have you tried putting the plug into the wash basin. Mine gurgles when at anchor in anything other than flat calm water.

[nigelhopkins]

That's a possibility!
Thanks you I will try that when I'm back out in June.

[tomina]

I have a funny feeling that what you are describing is water slopping gently back and fore in the forward water tank……are you sleeping in the vee berth forward. In which case you are likely on top of the tank and a part filled tank will ‘slop’ about making these gurgling noises. So, either empty the tank and listen. Or, fill it and listen! That should confirm one way or the other. Mine gurgles best at about two thirds full!!
Hope that helps Michael Solano & Julia Too

[nigelhopkins]

Hi Michael and Julia
Thanks for the response. It's not actually that although we have definitely experienced what you describe! Jeanneau clearly went for low cost water tanks without baffles. I was going to start a separate thread to see if anyone has managed to add baffles or replace their tanks and solve this problem as what you describe is very frustrating.

[tomina]

Well Nigel.
If you have ruled out the water tanks, what about small waves slapping under the counter at the stern. This can be so bad on larger boats (upsetting the charterers aboard) that they manufacture special shaped inflatable tubes to mitigate this problem.
More than that I can’t think of anything else.
Michael Solano

[nigelhopkins]

Thanks Michael.
I'm interested in the inflatable tubes. Do you have a link?

[NZL50505]

If you Google transom slap you’ll find tons of stuff.

I doubt that’s the gentle gurgling noise you heard - you ‘feel’ as well as hear transom slap as the waves thump under the stern. If a big boat wake comes through from the stern it can be quite an alarming sound!

[sawduster]

We sometimes get this from water moving up and down through the kitchen sink seacock making gurgling noises up through the sink drain. We noticed it one windless evening with a slight side swell which was rocking the boat from side to side. Try closing that to see if it helps.

[nigelhopkins]

Thank you.
This sounds like a potential cause. It's so difficult to be sure at night when a) you're tired and b) you've overdone the food and drink! 
I am back out on the boat from Sunday so will be trying all of these to see if I can figure it out and will feedback.