Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 18/01/2017
A similar option to the single underhook is the double underhook pass, also known as a stack pass (and probably a bunch of other things). The main difference is that you're putting both your arms under their legs instead of just one. As soon as you can create enough space in their closed guard, slip your arms underneath both legs. Grasp around the outside and secure a gable grip (palm to palm), or an s-grip (four fingers clasped together). If you prefer, you can instead grip their trousers and lock your elbows, or indeed their belt: the problem with those grips is that the loose fabric may provide them with enough space that they can make room to escape.
Whichever grip you prefer, you now want to stack your opponent, driving forward off your toes. To get them in position for stacking, the two basic methods are to either pull them up onto your hips using your thighs as a ramp, or move forwards so you're close behind them and they are rolled up onto their shoulders. If you don't get them stacked and therefore leave space between their hips and yours, then they can still use their legs to stop you, such as by hooking under your thighs with their insteps. They will also try to walk back on their shoulders to make space: stack them and remove any space to prevent them. Once you've got them stacked, the aim is again to push their knee right into their face.
At that point, the process becomes much the same as the single underhook pass, as like before, you'll grab their opposite collar (or shoulder, if it's nogi or you can't get the grip you want) with one of your hands, sliding your fingers inside. That is just one grip, as you could also reach behind their head. An even tighter option is to reach behind their head and grab the shoulder. In that situation, be careful you don't start neck cranking with a 'can opener' (a crude technique from closed guard where you pull their head towards you), as that's illegal in most competitions for a reason.
Once again establish a wide base with your feet, while with the other hand you can hold the back of their trousers and lift their hips. Remember, it is important to keep maintaining heavy downwards pressure throughout this pass. Keep pushing until eventually you drive past their leg and transition to side control: don't raise your head, just keep pushing until you slide past, nudging with your shoulder if necessary.
Quite often, they will try to block your pass by bracing a hand against your hip. To remove that arm, bring your nearest knee either inside or outside their arm, pressing into the side of their elbow. That should collapse their arm. On the inside is easier: collapse the arm, trapping it with your leg, then slide into side control. If you go outside, you'll need to shift so that you slide towards their legs instead, keeping your torso low. Once you're passed, you can then readjust into side control.
Another option you should always keep in mind when passing is that you can always try changing direction and going around to the other side. This can be particularly effective if they are heavily committed to blocking your pass on one side. If you're able to quickly shift to the other side, they will probably find it difficult to reset and block that other side in time.
Teaching Notes: Next time, I'll talk more about dropping the hip as well as the shoulder, pressuring down and moving round. I don't tend to teach this one as much, because of the pressure it can put on the neck, but it's useful as an occasional addition to the single underhook pass. Most of the time though, I prefer the single underhook, though I do want to try Matt H's Faria version next time, where you don't move around so much. Instead, it's more of a slight lift of the head and gradually knocking the leg across. If you don't move around, they can't jam a hand into your hip, though normally I find that turn is a major part of the pass (hence why I'm interested in trying a version that changes that bit).