Interior gelcoat with patchy yellow stains

[SVTatia]

Originally Posted by fruityloop8

Thanks for all the comments.

Bob - yes I already discussed with the owner that this is something I would need to fix so will take it into account of my offer.

Some good suggestions of products to try. Is anyone familiar with what the stain may be? Anyone bought a boat from a heavy smoker previously?

I did, and the white gel coat was light brown. No problem, I thought, clean and polish just light a hull...
How naive, I tried everything, nothing worked. Due to the gel coat porosity, you'll have a hard time cleaning it up.

I sanded and painted, no regrets. Sand it lightly clean with acetone and apply a tie-coat prior to the finish coat of whatever paint you decide to use (I used exterior latex and after 6 years, no issues). The hard work is in masking and covering everything. I would suggest you don't use glossy paints.

[Dehler 25]

When I was boat hunting I noticed that several of the candidates which were all Hunters with the same type of interior finish had a characteristic yellowing to some degree, sometimes it was very apparent other times just a splotch here or there. My boat also has the same interior fiberglass but without any yellowing. My guess is that the discoloring is endemic to the material and painting would be the only cure. I did have a yellowing of the access panels used throughout and sanding removed it as they are smooth and not textured like the rest of the interior. It certainly is not mold.

[Valmika]

My Beneteau also has this occasionally it the gelcoat of cockpit interior. It is splotchy and seems to be were surface goes around a corner. I'm still not sure what it is but it does go away after my topside cleaning crew show up. Gelcoat is porus so start weak with bleach and work your way up

[Captndave1]

could be like the intercostal mustache stains. use toilet bowl cleaner to remove.

[mikedefieslife]

Originally Posted by UFO

Always had great results for surface based stains with Grunt - Phosphoric acid based i think


https://www.whitworths.com.au/grunt-...-remover-500ml

This. Phosphoric acid makes Oxalic acid look like Oil of Olay. It is much faster acting, and of course stronger. Not much more expensive either. In fact here in France it is cheaper.

[Captain Puget]

Can’t be sure without seeing it, but had similar residue after removing a glued on liner covering on an old boat (kind of looked like a heavy, textured wallpaper used for insulation, I guess).

Some areas I got fairly clean, but way too much effort and never looked right. Ended up painting.... prime first.

[Mike Banks]

Does your vessel have balsa cored decks? Just askin'

[Clivevon]

It does look pretty bl**dy awful - shame. Who wants to live with that on a modern boat?

IMHO offering a boat for sale in that condition is either lazy or its a real problem. Either way the seller has had plenty of time to fix it so I wouldnt personally have much sympathy for him. He has made a choice.

Personally I would reckon that deck is cored so I would put a moisture meter all over above & below deck just to make absolutely sure its not a complete deal breaker with a wet balsa or ply core seeping through & staining the deckhead. Fibreglass, epoxy, gel coat etc is NOT waterproof - not absolutely 1000% (according to my surveyor) - so that is not impossible.

That being done all OK, if you still want the boat I would maybe agree a price with the seller with NO stains at all - gives him the chance to clean them off himself if its that easy.

Assuming he doesnt want to clean it - so it is completely clean & stays that way - then I would assume it needed painting, not cleaning. I would most definitely NOT want the seller to paint it or get it painted - you might get a very temporary quick fix which you will soon have to do again.

I would get a specification & quote for a good quality permanent job from the local boatyard, & knock that full cost off the agreed price. Why make the seller a gift of your own time & labour? If you do then chose to DIY, thats no-one elses business but yours.

Of course, if there is a queue of buyers for the boat, you might choose to compromise, but used Bavarias aren't exactly rare... Plenty of fish in the sea & boats up for sale.

Dont misunderstand me - I'm not saying screw the guy down to the last cent. Much better to stay on pleasant but fair terms. But with that issue the seller has to be expecting a price downgrade, or else to find a buyer who doesnt care about those stains. Wont be too many of those around.

Good luck.

[jdaltonpe]

I bought a boat with the same problem but it was the whole interior, not just the headliner. It looks like the gel coat was just rolled on leaving an orange peel effect. Not sure what the staining was but I suspect it was some oils or something leaching out of the gel coat. I bought a couple of gallons of acetone, put some elbow grease to it and it came out fine, has not returned in the past year.

[ronstory]

Don't forget to give the Magic Eraser a try.

https://www.amazon.com/Mr-Clean-Clea...41079435&psc=1

[fruityloop8]

Thanks for all the advice!

Worrying to think it could be balsa staining from a wet core. The deck felt solid as a brick, but we would obviously have a surveyor look over it and take humidity measurements.

Think ill try some cleaning first, see how big the problem is, and prepare to have it painted if that's what it takes - only if the deck comes back dry!

[Hardhead]

Originally Posted by mikedefieslife

This. Phosphoric acid makes Oxalic acid look like Oil of Olay. It is much faster acting, and of course stronger. Not much more expensive either. In fact here in France it is cheaper.

I've always had the best luck with oxalic acid for tough stains - but never tried phosphoric acid at all. Has anyone run into any problems with phosphoric acid damaging or staining gelcoat/fiberglass, or stainless steel?

[UFO]

Originally Posted by Hardhead

I've always had the best luck with oxalic acid for tough stains - but never tried phosphoric acid at all. Has anyone run into any problems with phosphoric acid damaging or staining gelcoat/fiberglass, or stainless steel?

Used it a few times - Around stainless steel stanchions which had leached a bit of rust stain onto the deck - No problems at all - It cleaned up the stain and everything looked brand new. Just gave the deck a bit of polish and a buff afterwards.


The guy I bought it off told me he had put it on once and accidentally forgot about it until the next day - No issue at all.

[Hardhead]

Originally Posted by UFO

Used it a few times - Around stainless steel stanchions which had leached a bit of rust stain onto the deck - No problems at all - It cleaned up the stain and everything looked brand new. Just gave the deck a bit of polish and a buff afterwards.

The guy I bought it off told me he had put it on once and accidentally forgot about it until the next day - No issue at all.

Thanks UFO - greatest tip in the Universe.

[Tsuru]

Originally Posted by coopec43

I have no idea but have you considered oxalic acid?


https://www.doityourself.com/stry/4-...or-oxalic-acid


https://hurricleanlouisville.com/rus...louisville-ky/

That's what I'd try first. Probably one of the hull cleaners with oxalic acid.