Tony, the first question is.... is there any remaining antifoul on the hull? If so do you know what type it is? You should be aware that there can be compatability issues between different types of anti-foul. It's unlikely that this will be an issue, as owners of fast planing craft will probably choose the same type. But check if you can! I believe that most people opt for International Interspeed Ultra (for RIBs).
There's loads of info on the International Paint website, and there's a compatability chart on there too if I remember correctly. www.yachtpaint.com
They do a quick reference here: http://www.yachtpaint.com/UK/boat_pa...ing/choose.pdf
Their FAQ is useful, and gives a very concise answer: "Power crafts (speeds in excess of 25 knots) and boats kept on drying moorings should be coated with a hard antifouling, Interspeed Ultra".