Re: Should I be able to cast my 3wt as far as my 5wt?
Like Gator said, try to watch your back-cast until it completely unrolls backwards. You'll want to make sure it loads or completely unrolls behind you before you begin to accelerate forward. I'm not a casting instructor by any means, but the best way I have heard a cast simplified was into three parts. A back cast, which is an acceleration to a stop; the STOP until the line unrolls and loads the rod, and then a forward cast that is a mirror image of the back cast, accelerate to a stop.
I also exagerate my arm motions when I'm trying to reach with a short rod. I try to allow my arm to be an extension of the rod and move all the way down to my shoulder, rather than just keeping my elbow tucked like Lefty prescribes. I can pick line up off of the water, and carry line in the air like my rod is a foot longer by elevating my casting hand a little, and pushing it far behind me during the back cast, and ending my forward cast with a stretch forward also. Again, I'm not a casting instructor so if the way I do this is detrimental to good casting form maybe someone can correct me as well, but I've found that this allows me to reach without overpowering a soft rod.