Car bog on epoxy

Other then the moisture absorption issues, flex and vibration are the doom of these polyester fillers. You know it has to come off, but it doesn't have to come off now. You could put a paint job on it and see how it goes, knowing full well, at some point she'll be back on the hard for another go 'round.

Yeah, it's a waste of a paint job, so maybe not a 3 pack, maybe just a single part polyurethane, so you don't feel as bad grinding through it, when the time comes.

Polyester fillers are quite soft, so it's removal will be fairly easy, without doing much more than scratching the epoxy under it.



A flap disk (different than a flap wheel) does a good job of knocking down filler, while not tearing up too much surface under it. Use in an angle grinder or buffer. A flap wheel will work too, though usually leaves tracks, the width of the wheel.

 

Use can also use heat.

Normally at the shipyard we line up all the boats with bad bog , then gently cook them on friday afternoons.....cleanup and rebog on monday.

Bog softens fast at high temp.

Saves much labor and sandpapering.



subir fotos

 

Heat works though is difficult to control if interested in saving the epoxy undercoats.

 

Probably one of my favourite nightmares - digging into an area and finding polyester body filler under the fibreglass/gelcoat/paint, whether epoxy or polyester layup.
Then I'm forced to keep going 'til its all out.

New build or refurb (in epoxy/glass), it is way better to use epoxy with microballons or suitable mix of fillers to fair. Clean coat over it too for sealing, then paint. Works OK for me though I've not done a 40' beast!.

 

How thick are we talking here? If it was just a light skim it might be ok... Was it just the deck or elsewhere too?

If it was it put on thick then I'd go and hire a floor sander to take it all off...

If it was just a light skim then I'd apply some cheap non skid and see how it goes. Fix it later if it presents a problem...

 

If it has been plastered on heavily, you have an unnecessary weight penalty as well as the other problem.

 

the glass was laid down with epoxy resin, then the whole lot was covered in a layer of q-cell/cabosil/epoxy mix which was then speed filed back to show the highs and lows and then the rest of the fairing from there was done with car bog - with the exception of anywhere we thought it was going to be thick then we first put the q-cell mix down first before the bog went over the top.

So i guess there will be patches where its literally a skim coat and other spots where its maybe up to 2mm thick.

 

What topcoat colour will the finished boat be

 

Undercoated with High Build 2 Pack primer then top coated with White 2 pack DuPont

 

White is a good colour. Low solar heat...your bog will have an easier life.

 

Although auto body filler isn't terribly strong, if it really is that thin (0-2mm), you might get away with it for a time if it is just on the deck. Auto body filler has to be able to handle some heat (think about a black car in the sun). So you should be ok there. It is made to stick to steel, but steel has a much lower coefficient of thermal thermal expansion than epoxy/glass, so the body filler to epoxy joint should see fewer thermal stresses. The compression and tension loads on the body filler from the flexing of the epoxy/glass/ply underneath will probably be the worst for the body filler. The fact that the filler is thin helps here.

If you think of a deck as having a limited wear life before getting resurfaced, then you might just live with it. But my decks are more non-skid than beautifully faired structure.

 

Back in 87 i worked on a 55ft steel motor yacht that had been built by a well known yard on the upper reaches of the tidal Thames. She was originally faired liberally with polyester filler up to half an inch thick. We had to replace a load where it was falling off, ten gallons went nowhere & in the end it took twenty.
Dreadful stuff!