For the last 2.5 years I've been working with some friends on Goju Ryu kata, and I think we're onto a good method of decoding/structuring bunkai. It's gotten to the point that we aren't finding any more flaws so I wanted to post some of our findings here to see if you guys could.
The video is a 2min runthrough of Sanchin Dai Ichi. We walk through the whole kata then give a few examples of how the end techniques can work when given more power.
The kata has three distinct sections. The first section of three forward steps is a progression to a clinch with double underhooks and head control. The second section is five stationary punches which represents all the things to be aware of while in the clinch. There are two attacks you can do, two attempts to escape from them that you can recover from, and one that you can't. If they get out of the Sanchin clinch then the third section starts which is to cover. Dropping your weight on their back keeps them from shooting for your legs because it's basically a sprawl. After the initial cover, we call it "the panic," there are four more covers which we beliere are two sets of two. There are two sets because there are two positions for their head and they each require a different set-up.The first cover is to get your weight fully on them and keep them tight to you. You may accomplish this with the panic cover, but you might not. The second cover is an underhook on the side opposite the head, hook the arm, and step back to yank them off their feet. If aren't yanked off their feet the last technique is to keep their arm clamped, keep your elbow on the back of their neck, pivot down to clamp their head, and push.
The most compelling thing about this explanation to me is how many ancillary karate questions it answers.
Why do so many Goju Ryu kata open with the double middle block position?
Because it's a progression to a very dominant position.
Why curl your hips forward in Sanchin stance?
Because it drops your weight directly down on their neck.
Why do half circle steps?
Because it drives their weight to their back leg and lets you drive straight forward.
Why punch with the heel down and tense at the end?
Because impact happens mid-way where you can still get hip drive. The end of the punch is a clamp.
I hope that made some sense. If you have any questions I'll do my best to answer. I welcome any comments, criticisms, or nick-picks. We want it to be as water-tight as possible so any new perspectives would be great. Thanks.