gelcoat/Paint cracking

[hatterass]

Ok, I asked this question a few weeks ago and now I have pics. What happened to the side of my boat and what are all the layers? I tried to put the Pics on the site and they were to big so I put them on my site sorry. They are under "photos" Thanks
Dave
Ctboatingeducation.com

 

[MikeP]

If that was a picture of a car, I'd say that it looks like body putty with paint on top! That type of cracking is a typical failure mode when Bondo is improperly applied/too thick.

It doesn't look at all like a FG/resin material at all. I suppose someone could have repaired the boat with too much putty. I'd hate to think that is the original material. If so, it's mostly putty/filler with hardly any FG.

 

[hatterass]

That was my thought, i can't figure it out. Or how I should go about fixing it. will it come back and what could have cause a failure like that.

 

[yachtsmanbill]

That really does look like someone did a quick-n-dirty repair to maybe sell the boat. I would say its automotive filler thats thick and maybe improperly mixed, then frozen and it all expanded at a different rate. You might be able to patch it, but it will be just that, a patch. You really need to grind all that stuff out and get down to the substrate for a decent repair. ws

 

[Brian Degulis]

That look like what happens when a harsh solvent paint like Awlgrip or Imron is put over a 1 part Alkyd primer or paint. As already stated you need to get it off and start over.

Brian

 

[Boatsb]

I have furniture with that effect (on purpose but dont ask me why) and I believe they do it with non compatable layers. Brian is probably right on. I would bet you need to go down to bare glass, Barrier coat and go from there.

 

[hatterass]

So I am going to ass u me that the black stuff is the fiberglass and that is where it has get ground down to. If it is not a repair I am worried that the whole boat will get like that. But everybody's belief is that it is not original and I don't have to worry?
D

 

[34Hatt]

Dave the Black stuff is original, Hatteras applied this after gelcoat. In the mold they did gelcoat then this black primer of some sort. Many say they did this so that you can not see light thru the glass. Then they did the lay up after pulling the piece they sprayed the paint. Now 35 years plus how many layer's of paint have been added????
If you are seeing the black then no major repair has been done in that area.

 

[BUSTER]

Dave the Black stuff is original, Hatteras applied this after gelcoat. In the mold they did gelcoat then this black primer of some sort. Many say they did this so that you can not see light thru the glass. Then they did the lay up after pulling the piece they sprayed the paint. Now 35 years plus how many layer's of paint have been added????
If you are seeing the black then no major repair has been done in that area.

That is exactly what it is. Sometimes the gelcoat itself will craze "fiberglass Pacemakers in particular" and an owner will apply a quicky paint job to cover it. In a coulpe of years the solvent completely evaporate and the cracks photo thru the paint, then the paint itself cracks in the same place. Dupont,Sterling and Awlgrip all make a high-build low shrink-back primer to cover the cracks.Of course all old paint must be removed and a reasonable amount of the cracks sanded.The nice thing about these primers is that you can apply it right over a 60grit profile,sand it back and get a good base to work with.

 

[hatterass]

Ok that is what I was hoping for. So what I have is the black glass then gelcoat and the primers/paint. So do I need to take it down to the black gelcoat or, can I sand off the old paint use the high build no shrink primer and be OK?
D

 

[BUSTER]

That's about it.Whatever you do,don't use a small automotive DA for all the paint and fairing sanding or you will be digging holes,making for a wavy finish.Use a Viking air file or a random orbital sander with a large pad,as much as you can,especially for the final sandings.

 

[34Hatt]

That's about it.Whatever you do,don't use a small automotive DA for all the paint and fairing sanding or you will be digging holes,making for a wavy finish.Use a Viking air file or a random orbital sander with a large pad,as much as you can,especially for the final sandings.

Yup like Buster said here Bigger is better it will be flatter. Have fun
Yeah right good luck.

 

[hatterass]

So when I sand I should use a large orbit sander. Just to make sure I have this right ,Do I
1)want to take it all the way down to the glass
2) just grind out the cracks (so I will most likely grind it down to the glass)
3)Just sand enough so it is smooth and I can have the yard spray the high build primer on?
Thanks for the clarification.
D

 

[34Hatt]

Dave you need to go until it is smooth every area can be different. Most likely you will be going almost to the black primer. That is how far I landed up going to on most area's.

 

[BUSTER]

So when I sand I should use a large orbit sander. Just to make sure I have this right ,Do I
1)want to take it all the way down to the glass
2) just grind out the cracks (so I will most likely grind it down to the glass)
3)Just sand enough so it is smooth and I can have the yard spray the high build primer on?
Thanks for the clarification.
D

In addition to 34Hatt's advice,you can roll or brush the high build primer if you wish. It needs to be sanded out and most likely will take more than one coat at least in some areas,if not the whole hull.

As you sand your primer,keep a pencil handy to circle any imperfections that need more filler or primer. At the end of your sanding session you will know where to go next.