Best way to remove barrier coat
I think good old boat did an article recommending "soda wash", a blasting technique using bicarbonate of soda. Effective and very friendly to the environment. I have also seen water/sand blasting recommended. For DIYers, your options are sanding or chemical strippers. According to Don Casey, there are chemical strippers available that are compatible with (i.e. won''t destroy) the fiberglass under the paint.