A half-halt is used to get a horse's attention, and to ask him to balance.
You use a half-halt when you are about to ask the horse to do something:
to go from a trot to a canter, to make a turn, speed up or slow down
without changing gaits, or most anything.
The half-halt itself is not a request for a change of pace or direction.
When you half-halt, you should not slow down, speed up, or make a
transition; you keep going at the same gait and same pace you were going
before. You just want the horse to be listening for you to ask him to
speed up, slow down, transition, etc. Similarly, you don't want the horse
to start to bend or weave around or wiggle in place. You want him to keep
moving steadily forward just as he was doing, with his weight shifted a
bit to his haunches to prepare for your signal.
How do you give a signal that asks the horse to just keep going, but to
listen up? What you do is this: you ask him to slow, and to go, at the
same time. Keeping contact on the reins, you squeeze your seat to ask
him to slow down, and you squeeze your calves to ask him to move
forward. In a "half-halt," you use all the signals you would use if you
were asking the horse to whoa, but you stop asking before he slows
down--"halfway" to the halt.
The amount of rein, seat, and leg you use will vary from horse to
horse. Some horses will need more leg than seat, for example, and some
horses may need you to squeeze the rein a little instead of just
keeping the same contact. It shouldn't be hard to "feel" how a horse is
responding, and adjust your signals.
Using the Half-Halt: An Example
In this example, you will enter the arena at a trot (blue), go
straight, halt (green), trot forward again (blue), turn left at the far
end of the arena, turn left at the corner, and make a circle (red) when
you reach the middle of the arena. you will be giving many signals to
the horse, asking for changes; before each transition or turn you
should half-halt to ask for balance and attentiveness.
After you enter the arena, you will half-halt (purple) about two
strides before the center of the arena. Then you ask for the halt.
From the halt, you will trot on. About two strides before you reach the
far end of the arena, you will half-halt (purple) to let the horse know
that you are about to ask for something. This will also balance him and
get him physically ready for the turn. After the half-halt, you will
begin to signal for the turn.
Along the arena rail, you will do the same thing: half-halt (purple)
about two strides from the corner, in order to balance him and get him
ready. Then you will begin to signal for the turn.
After the corner, you will proceed along the rail at a steady trot
until about two strides from the center. Again, you half-halt (purple)
to prepare the horse for a new signal. After the half-halt, you begin
to ask for the bend for the circle.
In the circle, in order to keep the horse moving steadily and nicely
bent, you may need to half-halt occasionally. This will keep him
attentive to you, and well-balanced in his turn.
Use the half-halt, a gentle stop-and-go aid, when you are about to ask
your horse to change what he is doing. He'll be alert for the change,
he'll be ready, and you will find that your ride is more smooth and
steady.