Well I wonder what the deal is with the rest of his crew and ship. The ship isn't coated except for one portion
here http://mangastream.com/read/one_piece/90932202/3
Ok so when those no names get owned by hodi jones their ship was coated but then when he was done with them they put them in a bubble to float them back to the surface. When they left their base the were underwater, so it looks like jones' crew can all remain under water coating and bubble free but decken's crew might have some fruit users seeing as how a portion of his ship is coated. It looks like hodi's crew doesn't require a ship that needs a coating.