Use 800 grit water paper and the blue will pop right back, had a H16, same colour, same problem, oxidized almost white, spent the better part of a day sanding out oxidization but well worth it. Finish off with poliglow to seal, protect and make hulls shine, hulls looked almost new when I finished. Check out my old H16 here:-
http://www.thebeachcats.c…ictures/?g2_itemId=72226
Turbo