What is the purpose of the line that attaches to the top of tiller?

Getting to know my new boat -
What is the purpose of the line that attaches to the top of tiller? Seems to limit the travel of the tiller.
On the rudder, the bolt that connects the rudder to the boat is a 5" SS bolt with nut. Also the bolt that connects the tiller to the rudder is a 2" SS bolt and nut. These require 2 wrenches to attach.
Is this standard? It looks from the week's website it might be replacement/upgrade equipment. Just not used to needing wrenches to install these.

Jeff,
That is used to help keep the rudder up while moving the boat around on land.
The spring is not enough most of the time.

thanks Chris, I'll experiment with that a bit. Also, does it serve any sailing purpose to have the tiller under this side to side line?

Oh Yeah. It keeps the tiller within reach. Without it the tiller will go way outboard.

OK, sounds logical. thanks