Current is relevant more in rivers than canals, and yes, down bound vessel has right of way. Generally speaking a port to port passing is preferred in canals. As Lodesman mentioned there are some funny
rules on the great lakes
, for example above the Sault locks there is a deep draft
channel on the West side of the river, so deep draft
vessels (as in deep- not cruisers) always take the West channel regardless.
And to specifically answer your question, if he's not sticking to the right, any where in Canada
or the US, he is likely to try to communicate with you some how (even if it's an embarrassing 5 short blasts from his whistle). In most cases you'll be okay sticking to the far right, staying out of the way of much larger vessels as necessary, even if they're crowding your side of the river, they draw 30 ft, you draw 5 ft (or whatever you draw), you can be further towards the right then they can be. Either way a commercial
vessel shouldn't be running you down, because at the end of the day- as long as you're not being goofy, the ColRegs, clearly state that it's every mariners responsibility to avoid risk of collision
regardless of RoW. Hope this helps.