Star Wars Episode 6: Return of the Jedi - Is That the Same Rope from Poltergeist?
The swing that Luke and Leia take to get away from the soon-to-be-destroyed sail barge is impossible, because whatever is anchoring the rope would have to be suspended and in between the two skiffs.
Have you looked to see if there is a bar protruding from the barge ? I haven't seen it in a while but I thought there was a metal bar sticking out from the top . Or it could be a Jedi trick and the rope was there to make Luke look heroic . Ha ha !
Perhaps the rope itself was an ancient Jedi, using its powers to hover in the air, sacrificing itself to save Luke when the Barge Explodes (c'mon, how's a ROPE gonna get away from a huge explosion??)