Well Scheme of course always goes nice in hand with any strong <$4 attack (Sea Hag e.g.).
I do understand the point, but a lot is dependant on the deck with Pirate Ship. Wouldn't go for that combo with Tunnels / (cheap ?) +$x cards in the deck / heavy trashers. It just helps your opponent instead of blocking him.
Another one that I did recently try is Ambassador/Pirate Ship. Throw over all the junk to your opponent, get a deck of less than five cards
You can buy some money if you want - but when you start buying greens, your deck is going to grow, so be careful. If you keep the decksize limited, his pirate ship can never reach anything. You on the other hand attack each and every turn. Of course, again, the conditions above still apply ...