I think the OP means Boat Bluff up near Klemtu, it's narrow with sharp turns for large vessels but cruise ships and the ferry go through there, plenty of room for a 12 footer. The passage won't be a problem if timed for a slack tide, same goes for all the narrow passes in BC waters that have fast currents and rapids on spring tides. But getting further south will be a much bigger problem. Rounding Cape Caution and crossing Queen Charlotte Sound would be crazy in a small tinny on all but the best of days. And if you stay on the mainland side you still face open water swell plus there's no fuel or services for a much longer distance.