I reached out to Altex and they said would need to remove before putting #5 on.
We put Warpaint over Vivid Petit and the adhesion isn't the best.
When we get barnacles it pulls Warpaint off down to the vivid.
Caught in this as well, so I am asking the obvious lazy question - is it actually absolutely required to scrape back the old Warpaint?
Assuming the normal prep for a like-on-like over-coating is completed, would there be a problem just overcoating the old Warpaint with a different ablative eg #5?
I wouldn't worry about that, the boatyard is empty because everyone goes to Whangarei , where every boatyard is full and buzzing, businesses doing well etc etc.