We assume here you have developed a passable ability to make a basic fly cast. If not, check out our page Learning the Basic Fly Cast . Once you have this down, there will come a time when you want to be able to make a roll cast.
There are scenarios on streams where the roll cast is the only option you will have. Also, it is a nice cast for certain fly presentations you'll want to make.
The Roll Cast
In many circumstances there is simply not enough room for a traditional cast due to lack of casting space behind the fisherman. It is possible that the fisherman might be able to turn in the stream or other body of water to allow for more room but then that limits the water to which you will be casting. In response to this, the second cast the fly fisherman should learn is the roll cast. The basic physics remain constant, but some additional techniques are required. The following video does a nice job of detailing the considerations involved.