Banging noise - help please

[carolinacoast]

So we are at the dock, and have a noise that sounds like a tapping and banging door starboard aft, with a beam breeze today and almost no waves.
I had a diver under the boat this week, and nothing. I have had the bed apart, and the drawers out and nothing moving. Swim platform brackets all appear fine.

It is driving the admiral a bit crazy, and understandably.

It has a dry sound. When I go outside, I feel the hull and it seems to be 3' or so above the waterline.

I'm thinking it is a mount for something, but just cannot identify it. Mechanic suggested something in the muffler, but it vibrates and sounds like it hits the hull from the inside.

Any suggestions? Would really like to solve before tonight.

Thanks in advance.

 

[Toolsntoys]

Is it possible the deck drain hose came un clamped.

 

[Plan B2]

Intersting and it sounds like you have already elimin ated all the usual suspects. I would check:
Top bearing for starboard rudder post
Master head exhaust fan mounts

 

[cb48lrc]

Dock side water regulator?

 

[SEVEN]

Is anyone doing anything when it happens. Like turning on the water? A thought, check the sump and the stern bildge pumps.

 

[seasalt]

I had a similar sound while in Columbus Marina on the Tenn Tom in Mississippi. It was large Carp thudding on the hull to eat whatever was growing on it. Took a while to figure that out but wasn't a rare occurance.

 

[carolinacoast]

So it sounds like a companion way door (located behind the built in cabinets starboard aft-which of course does not exist) that is unfastened in a beam sea with no lockset and when it bangs vibrates the hull and swim platform. I can even feel it in the salon through the carpet.

I assumed it had to be a loose arm to the autopilot, rudders, something.

As loud as it is, it should not be this hard.......

 

[Scarlett]

If the small wind waves are coming from just the right angle they go up the exhaust pipes and bang on the inside of the exhaust tube and can be amazing loud in the aft cabin, that is what we experience from time to time, just a thought. John

 

[jim rosenthal]

Plug the exhausts temporarily and see if it stops?

 

[carolinacoast]

It is just small waves. From the side, and we are at the end. WI'll try to disturb the flow. Will advise. Thank you.

 

[carolinacoast]

Diver called, and said it was a loose trim tab, and that he had another customer with the same issue.

Tonight the wind has clocked to the bow, so we can get some sleep.

Thank you for looking, and to the responders with good ideas. I appreciate it.

 

[dottieshusband]

I had a similar sound while in Columbus Marina on the Tenn Tom in Mississippi. It was large Carp thudding on the hull to eat whatever was growing on it. Took a while to figure that out but wasn't a rare occurance.

What he said, or if your in a saltwater environment, mullet do the same thing.