If the water is moving, unless you are intent on making time downriver, you can let the current take you and expend more energy steering and controlling the canoe, versus paddling. I've never seen double bladed paddles used in a canoe. Standard canoe paddles should work just fine, just be sure to maintain control of speed and direction - never let the boat go perpendicular to the direction of the water, otherwise you're swimming.

Good idea to tether an extra paddle - just in case.

I am 150% partial to kayaking - I've done my fair share of both kayaking and canoeing and I choose a kayak every day of the week and twice on Sundays. The only advantage a canoe offers is the ability to pack a bigger cooler! Either way, you should have a great time. Be safe and enjoy!
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