Wet Sandblast

[Art Femenella]

My 1988 Catalina 30 has hundreds of small blisters over the hull, and has a number of layers of bottom paint. I am considering having my yard wet sandblast the hull so that I can fill and fair the blisters, barrier coat and bottom coat. Anyone have experience with this approach? If blisters are shallow, is it better to barrier coat first and then fill? Thanks.

 

[John Dawson]

Fill first

The barrier coat is by definition not porous, so the bonding between hull (polyester?) and filler (epoxy?) would be superior. The barrier should go over everything. Also barrier coats reportedly do not last 'forever', while the filled blisters are 'permanent' bonds. Interprotect 2000 requires the first coat of bottom paint to be applied before the final coat of barrier hardens; in fact each layer of barrier coating has a window of application time for suitable bonding. That should tell you something if it won't bond to itself well when cured. If you use conventional bottom paints and sanding, you might consider a flag coat to protect the barrier thickness.