A C-1 is a decked canoe for one person. Decked means it has a covered top with an opening for the paddler. It looks a lot like a single person kayak but is paddled with a single blade canoe paddle, you paddle from a kneeling position as you would a open canoe.
Kayaks K-1, K-2 on the other hand are paddle with a two bladed paddle usually from a prone sitting position.
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Canoe racing - Wikipedia, the free encyclopedia