Steve Gurney is best known for winning the Coast to Coast race a record nine times. He has years of kayaking experience on the extensive braided river networks of the South Island. He knows more than a few tricks of the trade in choosing a good line on a braided river like the Waimakariri that is forever changing. Here are some of his top tips.
The Waimakariri is a braided river (very rare in the world) and requires a unique skill to navigate for a fast trip. A braided river has numerous shallow rapids spread over a wide and pebbled bed. It meanders, splits into multiple channels, and then these channels rejoin at different and varied places. The biggest challenge to beginners is taking a channel that runs out of water, requiring an arduous (and embarrassing) walk back to the main channel. For the competitive sharp end of the field, choosing the fastest channels can be the difference between first and second place.
There are five general rules that I teach kayakers who are looking to paddle braided rivers faster are below. (95% of the time these rules will give the fastest route, but very occasionally, there might be a small short-cut that could save a few seconds.)
(1) Look ahead
Look as far ahead down the river as you can, always scanning between a kilometer or a few hundred meters, to pick where the majority of the water flows. This enables one to more consistently pick the fastest flow.
(2) Biggest flow at junction
The biggest flow or biggest volume will move the fastest. It is also likely to be deepest and kayaks are much faster in deep water. It's often tempting to take what looks like a short cut, a smaller branch, shallower and skinnier, but invariably it is slower or sometimes runs out to a dead end.
If it looks like your 2 options are equal volume then use additional rules of (3) and (5) below to guide your choice.
(3) Equal Memory
Remember the historic flow: let's imagine you took a right in a previous channel choice. This means that as you paddle down this right channel, there a channel of water somewhere on your left. This channel on your left will eventually rejoin the main river, or another channel. So statistically, (and by the Law of Gurney :-) if you subsequently get a choice of equal flows, you'd be best to take the left one as it is very likely to meet the left flow that you previously didn't take.
(4) Early Bird
Sometimes you’ll see the rapid split off to the side in a series of small chutes, only to join up again in a deep pool or channel. When you see the first small chute split off, it’s tempting not to take it, instead staying with the main flow. And this repeats as the next small chute splits off, and so on, and so on until there is nothing but a shallow fan trickling through the gravel, and you have to get out to walk.
The trick is to always be scanning ahead to spot this type of braided rapid so that you’ll know to take the first possible chute that you can get your boat down.
(5) Low down puddles
Gravity plays a big part in determining where water eventually flows. Water will always end up at the lowest (altitude) point… it wants to puddle. So if you've been looking ahead as in (1) you'll be able to figure out which channel ends up lowest, and hence where there will be bigger and faster flow. The higher channel will likely run out of water.
It's all about consistently picking the deepest, fastest most voluminous flow.