Genrally, the easiest means to rescue boats in moving water is to bulldoze them to shore or a safe eddy.  This can be [performed with one of two boats.  Always remember to set a proper ferry angle, upstream part of the boat points at an angle to shore.  Sometimes you can hook the cockpit over the bow of your boat giving you a tad bit more control.  Bulldozing is generall the first choice as you are not tied to the boat making escape easy and fast.  It does take some practice to master this skill but well worth the effort.  I also like quick bumping and shoving the boat with my hand which may be even faster.  Here is an excellent demonstration of these techniques: Boat Bumping.