The Snake Roll is a very powerful cast and very easy cast to learn.
You just point your rod downstream and let the current straighten out your line. Now your fly is on the dangle. Very slowly draw the number 9 with your rod tip. VERY SLOWLY. In fact, make the circle of the nine pretty big.
You don’t need your entire line out to begin with. Start short to get the idea.
As a matter of fact, try just drawing the nine, big, high and slow. Don’t make your forward cast yet, just watch where your anchor re positions itself. It should slap down in line with your intended target. If the line lands on top of you or lands too close it may be because you made too big of 9 with too short of line.
Do that drill a few times. All you’re doing is allowing yourself some time to understand how the cast works. When it starts to make sense you can try slowly lifting into the firing position and slowly casting forward. Just don’t panic. Allow yourself to go slow enough that you blow a few cast, but make sure its because you went to slow, and not to fast.
When you get the idea, you can speed up the process. The main part of the cast speed up ever so slightly is the very last part of the 9 you draw, but don’t go crazy, accelerate just a little into the forward cast position and cast. It will be easier on you if you cast directly cross stream or even a tad upstream.
You don’t need a small, fast snake roll to begin with. Keep it slow.
After you gain an understanding of how the cast works you might find it easier to cast the entire head and speed things up, but only as much as it takes to make a nice cast. Feel the rod bend throughout the entire cast. Keep it smooth. The rod should feel heavy throughout the entire cast.