Final Fantasy X/S.S. Winno

You regain control of Tidus in the passenger quarters. There's a chest half-hidden behind the group of Besaid Aurochs that contains a Hi-Potion. Exit through the door and talk with O'aka a few times, and he'll ask you to lend him some more Gil — do so (101 is enough). Ignore Dona and Barthello and head up to the deck of the ship. There's nothing of interest in the steering room, so head to the stairs up to the balcony. You'll overhear Lulu and Wakka speaking about you. You can try climbing the stairs multiple times to see some scenes which serve no real purpose other than to enrich the story a little.

Obtaining the Jecht Shot
It's important you save here and now before doing anything else, because something important's about to happen that you will really want to retry if you mess it up. Head onto the front of the ship and approach the random blitzball there. Tidus is obviously still moping over his father, and you'll get another flashback or so. Time to prove Jecht wrong! The on-screen instructions are pretty good, so just do as it says. If you don't manage it (you'll know because Tidus will miss the ball when he spins to kick it) then reload, either by resetting the PS2 or using Square's handy soft reset (Start + Select + L1 + L2 + R1 + R2). If you manage it you'll have the Jecht Shot at your disposal in blitzball matches from now on. You'll soon see why it's important soon enough.

After the scenes and talking with Wakka and Yuna you'll rest. You'll be prompted to save — do so if you want, and afterwards, you'll be sailing into Luca!

Return
After you get the Airship again way later in the game, come back to Killika Port and take the boat to Luca again. On the top level of the ship, there's a guy studying Spira's animals who will ask you how many seagulls are flying around after you talk to him enough times. Count how many there are from every view on deck, answer correctly (11), and he will give you Wakka's weapon Ace Wizard, equipped with the first four levels of Magic +%'s.