Stephen Ash:I can't imagine that the metal grommets would be a problem but I'll look at Home Depot to see what rubber ones they have. About how big are the ones that you are using?
1" od with a 7/16" hole. I would just intuitively feel batter about soft rubber on urethane than metal on urethane in the event of ,say, a tank smashing the wing or some other unlikely thing. Have you decided that the wing needs a drain or are you just an avid tinkerer like me? If I come across any I'll mail 'em to you. I think I found them in the marine section of the LBTS Ace Hardware. They look much slicker than regular grommets.