The underhand cast is a
variation of the sidecast, the difference
being that with this variation the caster
throws the loop underneath the tip of the rod.
This is achieved by casting the side stroke
with a small downwards dip with the tip of
the rod ( i.e. the tip of the rod draws a saucer shape during the casting stroke).
The result should
be an upsidedown loop. The smaller the dip,
the tighter the loop. This variation is
particularly useful for casting beneath trees
and is often the only workable tactic - even
if the loop hits the overhanging branch, the
fly often kicks underneath and still lands on
target! A very useful cast on small steams.
One advantage of the
underhand loop is that with a strong positive
stop after the loop has straightened the end
of the flyline kicks upwards. Yet another
good reason to learn this neat trick!
An advanced technique is to make an underhand cast on the back cast, which forces the
loop to pop upwards (great if you have thistles behind you, or just a big heavy fly),
followed with an overhead delivery on the forward cast.
Because this is flycasting...
Note well: the title 'Underhand Cast' is also currently being used to describe the
Single Spey cast. The main emphasis being that the lower hand on a double-handed rod
doing the work. Historically the Underhand Cast was also used to describe the roll cast.
Many USA instructors refer to this cast as the Pendulum Cast.