Miraculously my protagonist managed to subdue the fire breathing dragon and knock it unconscious. He then tied up the creature which is as big as a double decker bus with a wing span measuring 50 meters from tip to tip. The only thing left to do is to take it back to the village, which is conveniently just across the lake, alive.
Suppose soon there will be a high tide - in the next hour or so. My protagonist wishes to make use of this opportunity to float the dragon and use it as a ferry to reach the other side of the lake. How can my protagonist make sure that his hunting trophy will not drown during high tide? Is there a way to determine the buoyancy of an uncooperative dragon?
This is not a freshwater lake.