Bottom Job Questions Please

[John]

Hi, I have a '86' Catalina 27 that I am doing a bottom job on. I have found a few "paint" blisters on the keel where the paint just didn't stick to it. While scraping on these spots I have found that there is a brownish putty like substance under the paint. The putty seems to be like a "bondo" type substance. I can keep scraping the paint and it will keep coming off providing I pry with my putty knife some and keep scraping. These blisters are NOT wet underneath, but just seem to be where the paint came up from bad adhesion. My questions are these: What is this brown stuff? What should I put down after sanding and feathering the edges of the paint so that there is good paint adhesion and to assure water doesn't get in at these places? I'm stuck, don't know what to do with this dilema. Any help will be greatly appreciated.

 

[LaDonna Bubak - Planet Catalina]

My thoughts

The brown bondo-type stuff you're seeing is most likely bondo (or at least an equivalent)! They use it to fair the keel. What you might want to do is after sanding off the old bottom paint, and assuming no other blisters, apply an epoxy barrier coat (with barrier coat additive). This would definitely stop an water infiltration but is a huge pain! Good luck!LaDonna

 

[Joe Ford]

Use a primer......

The brown stuff is probaby fairing compound so leave it on unless you want to re-fair the keel (not a hard job). When you are ready to paint, use a 2-part epoxy primer over any suspect areas such as old or new blister repairs, fairing compounds, bare gelcoat etc. The Primer and the first anti-fouling coat must bond chemically, so pay attention to time frame specified by primer instructions. I've used "Pro-Line" 2-part epoxy primer on my boat with good results, and it's easy, too.