Sitting in the back seat of a K2 ins not a chance to slack off, but rather a chance to play an important role in the boat. The role is critically different to that of the driver, and just as important.
The back seat paddler is often the physically stronger paddler, and can be the less experienced paddler. If you have a K2 where both paddlers are experienced paddlers - what a pleasure to see the boat fly through a tricky section!
Balance
The driver has a lot on his/her mind, and is sitting in the narrower part of the boat. Without overstating the obvious, one of the biggest contributions the back seat paddler can make, is to sit comfortably and stably in the boat. If the back seater is twitchy, or prone to moving around the seat a lot, it will make for an unhappy marriage in the boat.
Timing and power
The front paddler sets the stroke, and the back seat paddler has to follow it. Much of the efficiency of a K2 depends on the compatibility of the strokes, so much hangs on the back seat paddlers' ability to read the front paddlers' stroke, and to try as hard as possible to copy the timing.
This applies not just to paddle blade entry and exit. It is crucial to understand how the front paddler pulls through the water, and where the power output is in the stroke. Is the power output in a punchy burst right after paddle entry? Is the power output securely in the middle of the stroke, tapering of at exit? Or is it gradually increasing to a strong blade exit?
There are few instantly successful K2 crew. There is no real substitute for time in the boat, and adjusting to one another's stroke.
The back seat paddler will have hours to watch the front paddler in action, and once the strokes become similar, in style and output, the performance of the boat wil improve markedly.
In power-paddling, there is a prominent school of thought that the back seat paddler should put the blade into the water fractionally ahead of the front paddler, to give each stroke critical acceleration and inertia from the back of the boat. This is a very small margin, and perhaps worth dabbling only for the elite few racers!
Keep the boat on the wave!
It is the back paddlers' job to keep an eye on the boat when paddling on a wave or diamond. The second that the boat starts to fall off the wave, the acceleration must come from the back to burst back onto the wave, with all its associated energy-saving benefits.
Tactics
The front paddler has plenty to think about, and the crew will benefit from the back seat paddlers' ability to watch what is happening around the boat. Where are the other boats around you, and how are they doing and feeling? Is there an opportunity to put in a burst or a break? Is the following group closing? Or splintering?
The back seat paddler also has the privilege of combining a sense of how they are feeling, with a fair idea of how the front paddler is feeling, to make well-informed plans about when to go hard, and when to conserve energy.
Turning and rapids
Much of a K2's success in a rapid depends on the driver choosing good lines. But the successful execution of those lines depends on the back seat paddler.
Generally speaking, the back seat paddler needs to keep the boat moving forward positively. The minute the boat slows to a speed slower than the water flowing through the rapid, it will lose almost all of its handling ability, and become a piece of flotsam or driftwood.
A K2 has greater power in a rapid than a K1 and the driver may well choose to paddle lines that move boldly across the flow of the water. Here it is clearly critical to keep power coming from the back of the boat.
In tight situations, a skilled front-seat paddler will stop paddling, and use high strokes, telemark strokes and bow rudder strokes to steer the nose of the boat onto the best line between the rocks. Here the back seat paddler must keep paddling steadily, and make sure the boat is comfortable and stable.
K2's often seem like awkwardly long things to wind around tight corners. A skilled back seat paddler can make a big contribution to setting up the boat before it enters a narrow section and can make a huge contribution to steer the boat in situations like these by learning when to stop paddling and put in a hard, wide low-brace stroke to help sweep the back of the boat around a corner, or for instance by helping to pivot the nose of the boat around to get into a channel.
In big water, the front seat paddler going into a big wave or hole is going to get swamped by the water, and will be concentrating on keeping his/her paddles above the big water, so that a strong stroke can be planted immediately on the other side of the wave. That means that as the boat goes into the hole or wave, the front paddler will have to stop paddling and lift the paddles above the rough water.
The boat needs forward speed to punch through the wave, and during that second that the front paddler is hit by the wave, it is important that the power comes from the back set to keep the boat steady, stable and moving forward with enough power to punch through the wave.
Keeping the boat dry
It is generally the back seat paddlers' job to keep the boat dry, and while the driver is preoccupied with the pedals and steering, the back seat paddler generally has the pumps set up on their footrest, and will need to continually check if there I swater in the boat, and if there is, to pump it out.
Trust
Much of the pleasure you get from a K2 partnership comes from the sense of trust that will develop between the two partners.
Rough water canoeing is thrilling because it is dangerous. So trusting someone else to make the right decisions in a risky situation takes a lot of trust! These decisions might not always be right, but can nonetheless be shared and enjoyed, if there is a sense of mutual trust in the boat.
Have fun!