Update - October 6th, 2017
This week Liberal MP Colin Fraser made an amendment to Bill C-46 which removes the "propelled exclusively by means of muscular power" clause. This returns the ruling back to the way it was originally written.
The federal government is updating the Criminal Code as it works towards legalizing marijuana. In turn, older laws that don't quite have a proper 'home' in the Code are being updated. One of them pertains to the law that you can't drive a 'motorized vehicle' while being impaired. The issue being that 'vessels' are included in the law, but not properly defined. So man-powered craft such as canoes, kayaks, SUPs and other flotation devices are in a grey zone where you could be charged if tipsy but also maybe only get a warning.
The change in legislation that Parliament is considering is the wording "does not include a vessel that is propelled exclusively by means of muscular power." however this could still be amended before it becomes law.