A 2:1 system is pretty darn easy tio set-up and very effectivve.  Simply attach a pulley with a carabiner to the boat end and run a line from the anchor through the pulley and retrun to shore.  As you pull from shore, the anchor moves creating the mechanical advantage.  Your pulling power is matched by the anchor.

The main disadvantage of this system is it takes twice as much rope as other systems.  Heres a nice article on this technique: 2:1 MA.