Why is it conventional practice to do bong sau down between the top two dummy arms?

[Marnetmar]

I haven't really begun to question this until the past few months but it's been bugging me.

Wouldn't it be more biomechanically sound and in line with how bong sau is actually supppsed to work to just to bong sau into either arm instead of sticking it down between the two arms from above? What purpose could the latter possibly serve other than getting a rotator cuff injury?

(For the record I don't have a sifu to ask since I've been flying solo for some time now)

 

[Danny T]

When looking at the dummy the arm on your right side is the opponent's right arm and the opposite is the left.
If you bong on the outside of the dummy arm on your right when looking at the dummy you are bonging on the inside of the opponent's arm (wrong side). The angle of the arms is approximately then distance of the deflection of the opponent's arm would be. Hence the dummy is a fine tuner for the practitioner's movements and positions.

 

[Marnetmar]

When looking at the dummy the arm on your right side is the opponent's right arm and the opposite is the left.
If you bong on the outside of the dummy arm on your right when looking at the dummy you are bonging on the inside of the opponent's arm (wrong side). The angle of the arms is approximately then distance of the deflection of the opponent's arm would be. Hence the dummy is a fine tuner for the practitioner's movements and positions.

To clarify, I didn't mean to ask why not bong on whichever arm you want. What I mean is why do this:

Instead of this:

 

[KPM]

I haven't really begun to question this until the past few months but it's been bugging me.

Wouldn't it be more biomechanically sound and in line with how bong sau is actually supppsed to work to just to bong sau into either arm instead of sticking it down between the two arms from above? What purpose could the latter possibly serve other than getting a rotator cuff injury?

(For the record I don't have a sifu to ask since I've been flying solo for some time now)

You are absolutely correct! I came to the same conclusion long ago! It makes no sense at all to shoot the arm downward from above between the two dummy arms to do a Bong Sau. That is NOT how Bong Sau works in application! But you see this all the time in Ip Man guys doing the dummy form. The better thing to do is to drop the arms below the level of the dummy arms and then to step as you shoot your arm up from below and between the dummy arms to do the Bong Sau. This "shoot it in from above" Bong Sau is not found in Ku Lo Wing Chun.

 

[Danny T]

To clarify, I didn't mean to ask why not bong on whichever arm you want. What I mean is why do this:

Instead of this:

Ahh...
Yeah...we don't dive in over one arm to bong the other as shown in the first example.