In order to paddle technical rapids well, you need your packraft to respond to subtle shifts of your weight and to each and every part of your strokes. If you are not physically connected to your boat you are at the mercy of the water. The primary advantage of this connection is that it allows you to edge the packraft – all the way from a few small degrees, to allowing you to quickly combat roll your packraft if you happen to flip. If you wish to become an advanced paddler the ability to edge is absolutely crucial and it should be one of your primary objectives.
The main way to gain such a connection is to have decent thigh straps or knee cups and a moveable backrest that holds you upright and forward. However, there are a number of other factors that assist an advanced paddler to have the control that they are after. These days you can get packrafts with one-way inflation valves and made out of stretch resistant fabrics so that they can be inflated to much higher air pressures than the earlier models. Likewise many self-bailers are incredibly rigid due to their inflated floors. A rigid boat equals control whilst a soft boat equals the exact opposite. Being connected to your packraft means that you are able to create and transfer power between you and your paddle as well as between the boat and the water.
It also goes without saying that having a heavy pack on the bow of your packraft makes paddling technical water much more difficult. To understand why refer to Safety Tip #10 I highly recommend that paddlers attempting harder rapids use internal cargo bags inside their tubes rather than trying to carry a heavy pack on their bow. A pack on the bow makes edging much more difficult to control as well as reducing your ability to make proper stroke placements. Packs also block your vision of subtle features within rapids making navigation through them much more difficult. Using a packraft with a TiZip and storing your gear internally will go a long way to improving your connection with the boat and your ability to paddle more technical rapids.