Hunter 340 ceiling stains

[pilotmaker]

Can anyone provide some insight as to these black stains that are all over the cabin ceiling of a 1999 Hunter 340. The boat otherwise appears very clean and dry, no musty/moldy smell etc.
Puzzled.
Thanks for your help!

Ceiling_small1

• pilotmaker
• Feb 25, 2017

Hunter 340 ceiling stains

 

[finefurn]

My guess would be condensation. Try Installing one of those solar fans that you put in the cabin roof.

 

[Bill19233]

I had stains like that all over the ceiling of my 340 when I got it. They weren't really black, just darker than the ceiling color. Big circles and splotches in the main cabin and quarter berth. It was like someone with some weird stuff in their beehive hairdo kept bumping it against the ceiling. Like the movie you're probably thinking of now.
But nothing would remove the stains, until one day cleaning something else, I sprayed a ceiling stain with the Fantastik I was using, then got distracted and didn't wipe it down until a few minutes later, it came right off! Got all the stains off just spraying, waiting a few minutes, then wiping down. And they haven't come back.

 

[pilotmaker]

Thanks! I am going to try this!

 

[Lotte Lou]

Weird....I have a '97 340 and haven't experienced this. But I'm sure glad to know what to do about it!

 

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[Bill19233]

I think the stains are impressions of the blobs of glue or thickened resin that is used to bond the ceiling to the deck. And they transfer outside temperature and cause condensation just in those spots, because the air gap between the ceiling and deck insulates the rest of the ceiling. The areas are constantly wet for parts of the year and the ceiling discolors or even mildews in those spots. I noticed the wet patterns on my ceiling on a chilly and damp day recently. They may occur more in areas where there is a big difference between the water and air temperatures for part of the year.

 

[Ed Caldwell]

I sprayed a ceiling stain with the Fantastik I was using, then got distracted and didn't wipe it down until a few minutes later, it came right off! Got all the stains off just spraying, waiting a few minutes, then wiping down. And they haven't come back.

Bill, thanks for the tip. I had the brownish stains on our H340 ceiling in both main cabin and aft berth in several places. Using your method, they are gone!

I lightly scrubbed with a Scotchbrite pad, then wiped with a paper towel after letting the Fantastik soak for a few minutes. The residue that was removed had a strange smell, but I have no idea what it was. It clearly was on the surface of the ceiling.

 

[Bill19233]

Great Ed! So, I'm not crazy or I didn't somehow buy some weird mutated or irradiated bottle of Fantastik that will keep me from having any more kids. Probably half the other cleaners I've tried would have worked on the stains, too, if I had just shown a little patience and not demanded immediate satisfaction/results. "Contact time", that's the ticket!