In this stance (often called the Parallel Stance) the feet are parallel to one another and placed about ½ shoulder-width apart or directly below the hips. In many cases it may be advantageous to have the feet roughly shoulder width apart. The hands may be in many different positions depending upon circumstances, but the Yoi hand position is quite common when holding this stance in a static position.
Heiko Dachi can easily be established from Musubi Dachi by pressing the balls of the feet gently into the mat and then rotating the heels outward until the feet are parallel and the toes point toward octagon angle one.
The stance is easily established from Heisoku Dachi by moving the left leg slightly toward octagon angle three or the right leg slightly in the direction of angle four.
This stance is inherently more stable than Heisoku Dachi and Musubi Dachi, but is vulnerable to applied pressures, particularly when pushed or bumped from the front.
As you practice movements you will naturally move into and out of this stance with great regularity. Like most stances, it is transitory in nature and seldom held, in a conflict situation, for any length of time.
As alluded to earlier we utilize Heiko Dachi as our Yoi stance. When performing Yoi during salutations or at the end of some movement sequences you will likely be in Heiko Dachi.
Within Tensoku Ryu nobody is going to come and carefully evaluate how far apart you have placed your feet when establishing this stance. The distance between your feet will vary depending on your intended use for the stance and the circumstances in which you find yourself. We merely expect you to establish a stance that will work well for your expected application.