Safe Travel Through a Notched or Overtopped Back Channel Dike
Here's the scenario: You are paddling in a group of several vessels and you encounter an obstruction, a notched or overtopped back channel dike, and want to safely travel through.
As with any river navigation through known turbulence it is always safest to scout first and then proceed with caution.
Use the same method you would use on a mountain river rapids as you approach and then pass through any dikes that are recently overtopped (due to rising river levels) or any dikes that have been notched.
If you are alone make a landing to one side of the dike or the other and visually inspect the cascade. If you are with other in a flotilla of vessels, your safest procedure is to make a landing above the obstruction and inspect from foot. After inspection designate a scout vessel to go first. A radio or cell phone (if there is any reception) could be handy at this point, but the best method is to learn & use paddler's visual and audible signals [CLICK HERE for Paddler's Signals]. Once the safety & the route is determined all others can paddle through one at a time. Sometimes it might be necessary to pull over to the side of the rock wall of the dike and portage over. This decision depends on the paddling ability of each vessel and the river level (and to a lessor degree the wind, which can whip any area of river agitation into greater turbulence with higher waves and more chaotic conditions).
If everyone is game for an adventure and not afraid of getting wet (capsize) by all means proceed. Tie down all gear, secure valuables and follow the below instructions for signaling. However if any one vessel is less capable, and sure to be traumatized by a flip-over, make a portage. Regardless of which direction you take, use paddler's visual and audible signals to stay in communication. Remember a chain is only as strong as its weakest link. The group is responsible for safe passage of all vessels. Any good leader will automatically assume this responsibility.
[CLICK HERE for more information on Safe Paddling technique]
Water levels with respect to Dikes & Back Channels:
In general at or above medium water (say 20 HG in the Helena Reach) you can always find a safe route over any dike, but you might not find much flow in the back channel. Usually the back channels start flowing better above medium waters 25 HG, with good flow as the river rises to high water levels (around 30 HG), and strong flow as it nears flood stage. The river banks start going under water around HG40, and at flood stage 44 HG all banks will be underwater and there will be very strong flow in all back channels. Note: Remember that river gage readings vary with each gage.
[CLICK HERE: for comparison of gages]
1. Make landing above obstruction and inspect from foot
2. If passage is too dangerous for safe passage: everyone should approach and then pull over to the side of the rock wall of the dike in safe place and then portage over
3. If passage looks doable designate a scout vessel to go first and explore route
Scout: Use paddler's visual signals to alert others
4. Once the safety & the route is determined all others should paddle through one vessel at a time
5. Regroup on downstream side, make head count, make sure everyone is okay, and then continue your journey
Scout passes through obstruction or hazard and others watch for paddle signals indicating best route:
Direction: Scout holds paddle high above head and points blade towards direction others should follow.
Stop! Don't Continue: Scout holds paddle above head and waves it back and forth.
Follow me, this is the best route: Scout holds paddle straight into the air above head.
[add drawings for each scenario]
In some situations paddlers might need to signal each other immediately and the whistle hanging on your life jacket might be the best way to do it. Especially if you are too far to shout, or nearby towboats are too loud. Here is the system:
One blow: ATTENTION -- "Attention!" or "Look this Way!"
Two blows: STOP -- "I need to stop" or "Bring the group to a stop"
Three Blows: EMERGENCY -- "A paddler is in trouble" or "We have a problem"
You can combine the visual paddle signals with whistle signals for more powerful communication. This is especially effective around the roar of whitewater or throbbing of towboat engines or in high winds. Say you are the scout; you have run the break in the dike and you want to let everyone know to pass to the left side of the run for the safest eddy to exit fast water. Blow you whistle once to command attention. If some people are still not looking blow again. Once you have everyone's attention hold your paddle high over your head and point the blade towards the left bank descending to show the group the best route of travel.