Bilgekote

[Fishjack]

To answer your question - you will need to sand down to bare fiberglass to ensure good adhesion with any fiberglass resin (epoxy or poly). I used white Bilgekote in my bilge with good results - I liked it because all I needed was a quart or two and did not have to spend the $$$ on a gallon of paint. Saved that $$ for fuel..