OK, I see it now. But where do the cards go when you ship them? Do they stay there in front of you along with the ones that were simply 'played' and not shipped? Plus, do they equally count towards the end of the game reckoning?All cards you play go face up to your tableau. Every card in your tableau scores for the appropriate scoring tile you have at the end of the game.
Generally shipping cards to get them to your tableau is better than simply playing them there directly. But if other players have already used the shipping boats and it's towards the end of the game and you only have two mismatched cards, then it won't be many points to ship those cards anyway. If they match your scoring tiles, then playing them to your tableau and hoping that your replacements also match might be your best bet. I've seen people use a triple shipping action at the end of the game to turn their two cards in hand into six cards in their tableau (and they managed to get four cards that matched their scoring tiles for 12 points).