As they have done in the past, the producers will likely explain it with a back story. On the freighter, just before it blows up, Jin will be shown diving into the water. He grabs a piece of floating wreckage and begins swimming towards the island (where else is he going to go?) Some time passes between this time and the time Ben turns the wheel, so there is sufficient time for Jin to get within range and so he moves with the island. Why read more into it?