> Which is much of the reason why I was complaining about the definition of "efficient" that we were stuck to, here. According to the definition given, the raft would be more efficient.

Actually only you are confused about the definition. ;-) Put a canoe and a raft into a dead calm lake, and propelling the canoe via paddles would be more efficient than propelling the raft by oars.

You do have to mention the type of propelling mechanism you are using, by the way. By saying "canoe," you imply that you'll paddle it, but I've seen canoes with gasoline engines mounted on them.

Anyway, although I was joking with my opening comment, "efficiency" actually is not a controversial scientific term. It doesn't mean, "What will get you somewhere fastest with the least amount of energy," as you seem to be assuming, as evidenced by your objection that a person paddling it will need to replenish his energy supply after a time. Efficiency is, in a system, the ratio of energy used to produce work to the energy wasted. If you paddle a canoe, you're wasting precious little of the energy: most of the waste will be what is required to counteract the forces of wind and current; barring that, there's just the friction of the canoe against the water, the canoe and your body against the air, and whatever energy is required for you to move your paddle from the point you take it out of the water at the end of one stroke and plunk it back in for the next.
Stick on a gasoline engine, and you may get there faster, you may not have to stop and rest ever, and you may feel a lot less exhausted at the end, but the efficiency of the system is still inferior, as gasoline engines waste three times as much energy as they utilize.