[JBo]

go to a Boats US or West Marine, take the one screw with you. They sell stainless marine grade metric and standard and will have varing lengths of many sizes. Had to do this a few times already myself on the same issue. Buy as many variations as you "might" use, keep rest or return as you are talking about 2 bucks for 8 of each size....you'll need them sooner or later.