Off hand without knowing anything about this type of head; I would think that it should have some kind of packing in the area where it's leaking. Try taking it apart by unscrewing it to check and see if it either has a rubber washer of some kind, or a string type of packing that is normally obtained in a hardware store for faucets. I know for a fact the my sink pump faucet has a string packing. Also, you might check out the make and model of the marine head on the web to see if they have some kind of a rebuilding kit for it. This is the only advice that I can give you on this. I don't really think that it's any different than an outdoor faucet that is leaking at the top of the valve when you turn it on. Good luck with that.Joe