This probably wasn't made clear enough, but the idea of the graping hook is not to teleport the player to where it landed, but to constantly tp the player to the flying arrow. That way you really get the feeling of a grappling hook.
Not sure If this is possible with a fishing this because I do not know if that red thing at the bottom of the line is also considered an entity. If not you could calculate the angle the rod was used on and then calculate the bow the rod makes so you can tp the player to the right x,y,z coords. This however already sounds confusing so I don't think it'll be easy to implent.
@iCheeetah (you messed this up in
@The12thDoctor s thread :D)