The water hammer effect, wherein the kinetic wave of the momentum of an object continues on when the mass of the object is stopped suddenly and the result is an increase in the frequency of the energy is a useful but evasive martial method.
But what about using water hammer methods regarding the momentum of the duifang?
You see with training one can learn to cycle impact energy up into higher frequencies, but it is also possible to cycle your duifangs energy up from their own momentum and prevent it from exiting their body, thus inducing the water hammer effect from their movement but in a manner that works against them.
The trick is perhaps found in the method where you stop their momentum but allow no energy to be transmitted into you. I call this a trick because it is tricky.
I was hitting an object the other day that was giving me instant feedback in the form of audio sound waves. I found that when I surged forward and relaxed on contact, I barely felt the contact at all, however this light touch aspect had the most profound result in terms of the sound it produced. The trick of the method was to relax, to have no tension whatsoever in the striking arm, otherwise the wave of energy I was sending bounced back into me. I found that when I relaxed as I struck that I would make contact and then a split second after contact the wave of momentum would transmit, the most curious aspect of this was the delay between contact and the wave. If I tried to hurry the slap/palm technique then the result was not the same, if I tried to use force then the result was not the same.
The required relaxation is like water, you must splash and relax like water. Your hands must wave forward like water, if they use their own energy the result is not the same. I could actually see the surge of energy after contact, when my arms were relaxed it went quickly through me and into the object a moment after contact.
When I merely struck the object and my hand was not relaxed there were two major possible effects I noted.
The first was that the energy of the strike bounced my hand out and much less energy was transmitted and when it did it was not penetrating energy. The second was when I pressed my hand as I struck, instead of the force resulting in my hand bouncing back, or the energy transmitting, the energy dissipated in my hand itself, bouncing back into it but being trapped by the pressure, and it hurt. The object in question was a large hollow steel pillar after all.
So the funny part about this is how counter intuitive it is that the softest of contact, even on a violent forward surge, allowed the greatest transmission of force. And there was a transmission delay of the order of fractions of a second after impact. I am a fan of circular movement and conservation of momentum for sure, but now I recognize the place of the pause in a form during specific strikes, such as single whip. This pause is actually part of the strike itself.
This is key to understanding how to use the method on the momentum of an attack, by relaxing as you check the momentum of the duifang the energy of their attack dissipates into them. The greater the momentum of their attack, the greater the amount of force is that the duifang ends up absorbing. This force or wave of momentum is qi, a form of energy. In essence you use the duifangs qi against them. Not by bouncing, or deflecting but by sealing thier momentum before it arrives, and oddly the amount of force required for this is low. Sort of like using a few ounces to stop thousands of lbs, and certainly not in a manner of force acting on force, but at the same time the effect is not the same as deflecting the path of a strong strike with sideways pressure.
The secret, because it is counter-intuitive, is in the softness. The softer you become in striking, the harder the force becomes that is transmitted. It might sound strange, or perhaps easy, but either way it requires practice, and not on a heavy bag or another person. The reason a steel object is nice is that it resonates with the force of the blow and if you cycle the energy up you will hear the result almost instantly. If you hit a heavy bag this way you will not realize what is happening, and if you play around carelessly with this and another person someone could get hurt. This phenomena does not require an explosive jing to be powerful, the faster you move for it the more challenging it is to relax properly. However the result can be peculiar, I even did knuckle based punch strikes on the pillar and found that although the technique was much harder this way than it was for a palm strike, hitting my knuckles on the steel with proper relaxation did not hurt them, which is odd, because normally I do not hit anything hard with any hard part of my body. This is of course because of the nature of the wave, there was no momentum pressing on the knuckles in the strike, instead there was a wave going right through them. Needless to say this is not how most people strike and this type of energy play is all but unknown in taiji today, let alone martial arts.
The neat part about this is perhaps the relationship of the forward momentum to the wave issued. The momentum need not be of an explosive nature for the wave to be of an explosive nature. However the movement must be whole body, thus uniting the qi of the body into one jing. Otherwise in order to get power one is going to have to use muscular force and doing so prohibits this effect.
True softness results in hardness.