Distance specified distance joint.

So, as I understand it, a distance joint acts as a "pole" between two objects, allowing neither to move any further or closer then the distance between the two objects at the creation of the joint.

I am trying to get only a piece of this functionality. I am creating a fishing game, and I have a hook that I want to attach to a bobber. What I want is a rope, not a pole. The hook can get closer to the bobber, but not farther away.

Is there a way to do this?

Thanks

What type of rope/string? Will it be for flicking or dipping? Can you try using a sprite that gets longer? Origin on one end and action pointwith hook on the other.