@Ribath @Elmithian
since the trip takes ~3 days with good wind, and the series has already stated that good winds from Hisui's blessing can roughly half the time it takes, that's normally gonna be 5~6 days sailing at ~60 miles per day that's 300 or so miles of ocean between continents at most (could potentially be less direct distance but the ship needs to go a more roundabout route due to prevailing winds/oceanic currents)
that of course is assuming ship standards are, as with the rest of this world, at medieval earth standards and barring potential summoned beast assistance...and double speed actually DOES match up with good wind speed vs normal speed irl if you bother to look it up, admittedly double is the high end of the speed range, but not impossible, and lets be fair, she's a high tier nature spirit so it isn't unreasonable she could manage it