Sorry can't help you with the world is in another savestate problem. But the boat however.. could have been destroyed.. it happens far more often than it should. Especially in the swamps and plains. Where one small afk trip is enough for leechs or a fulings (in the plains) to destroy it.

If thew boat is gone.. can you see some of the mats floating around in the water? If its not deep you could take the iron out of the water.