The Centreline Theory
The centreline theory is one of the most badly explained subjects I've encountered on the internet, so I've decided to write my explanation of the centreline to help clear up the mystery, most people explain the centreline as being the green line splitting the two sides of the body up, that's okay, but that's not the full story lets take the centreline punch known as the character sun thrusting punch (Chinese Romanised: Yat Chi Cheung Kuen) (Chinese:日字冲拳) and the Wing Chun maxim "The punch starts from the heart" that first starting point on the body is roughly indicated by the black spot on the dummies chest, the green line intersects the black spot so indeed the centreline punch is starting on the "centre" near the heart, a lot of people punch high although keeping the punch in-line with the green line, but that does not mean that their punch is truly on the centreline, for it to be truly on the centreline it must also travel horizontally along the centreline indicated by the blue line, but how exactly do you establish where your real centreline is, that's where the red line comes into play, the red line is situated right across your nipples, so by knowing your body splits along the vertical midline (green line) and establishing where it intersects with the horizontal red line at the nipples you can then plot the blue line straight out from there, the blue line is the line your punch should follow, the black dot being the horizontal/vertical starting point of the fist although about six inches in front of that starting point, all your punches in the Siu Lim Tau should travel along that line, and as a rule of thumb all attacks should travel through this line even more so in chi sau, the more you examine your wing chun the more you will start to notice what i am talking about.