Damsel in distress unfortunately isn't the only way that sexism can manifest itself in media. One Piece is a lot better about it than many works, but it's still a shonen manga with the appropriate baggage. This doesn't mean we can't enjoy One Piece, flaws and all.
@Nex:
Wait. What? How? Ace got one cool moment in Alabasta before being beaten by Blackbeard (which definitely would have gotten cries of sexism) and then spending the majority of his screen time needing to be rescued. Compared to all of the women we've seen in this series (who have all been quite strong and independent, mind you) Ace would have been the most stereotypical "damsel" in the series.
He never asked for help. That is the main issue.
Oh well, go Hina and Tsuru.
e: And before anybody gets me wrong, I did enjoy the emotional parts of Arlong Park and Enies Lobby.