Copper coating old GRP hull?

[macd]

May I ask why painting epoxy in alternating colours?

So you can tell at a glance where you've got to with each new coat. It's common for barrier coat epoxy to be supplied in two colours.

 

[STOL71]

As I got some good advice on here I thought I let you know the outcome: decided against copper coating the boat as the copper coat is epoxy based and may 'lock' any remaining moisture in the hull. With just primer and anti-foul, I can easily spot blisters and grind them out when they are still between laminate and hull, before it gets serious and does more damage to the deeper parts of the laminate.
Thanks for your help.

 

[Puggy]

Well done. Sensible decision leaving all options open.