Bottom Paint

[capecodmoon]

I had been using ACT and the West Marine equivalent for 4 years when I got a "good deal" on multi-seasonal black Petit paint. I cleaned the bottom (didn't sand) and put on two coats. When the boat was hauled this fall, the yard pressure washed it and brought it back to my driveway. The next day, the paint was peeling off in large chunks so I pressure washed it. One side peeled alot and the other side didn't peel much at all. I wanted to pressure wash again about two weeks later but got a new hip instead so no pressure washing.
Any ideas? I am more than a little irritated at the situation because of the expense of soda blasting or the equivalent.

 

[Robbins29]

Was the Pettit paint an ablative like Ultima or Horizons? If so, it should have stuck. Since it didn't stick, I see no alternative to stripping it. A chemical stripper should do the job, or even scraping and sanding from the sound of things. I use the Pettit ablative Horizons on my Baybuilt workboat and have always gotten good adhesion. I suspect your bottom needed to be scratched up a bit before the Pettit was applied.

 

[arks1]

I've used Pettit Ultima SR for the past 5 years with no problem.

Pulled directly from the the Interlux ACT prep instructions:
PREVIOUSLY PAINTED SURFACES: In Good Condition: Wet sand surface with 80 grade (grit) paper to a clean firmly attached surface. Clean with Special Thinner 216. In Poor Condition: Use Interstrip to remove all traces of antifouling. Sand and wipe clean with Fibreglass Solvent Wash 202 for fiberglass and wood substrates. For steel, sandblast or grind to bright metal finish.

 

[aholst1]

Cape,
From an industrial coating perspective, Arks and Robbins have it right, the substrate needs to have a profile for the coating to "grip" to. Depending on the coating, a profile similar to 60 - 80 grit sandpaper (SSPC-SP13 which is for concrete) should work going over fiberglass. For steel in immersion service a "near white" blast cleaning (SSPC-SP10) is industry standard.
If overcoating be sure any previously applied coatings are WELL ADHERED and ensure material compatibility if changing mfg'ers. Meaning the solvents in one brand may actually break down the existing coating and cause it to loose adhesion with the substrate.

Arks1 - based on your comment, have you applied bottom paint 1x year x 5 years? If so, what is your material cost per application?
Thanks,
AJ