"What is torpedo looking thing sitting within a small Greek village by the seaside?"
A: "Years ago in the Navy, a ship I was stationed on had similar items for spreading out mine hunting nets and cables. You could drag these behind the ship, and depending how you tied off to it, it would ‘walk’ out away from the ship to the side taking nets or cables with it. I doubt this is mine hunting, but I bet it is (commercial?) fishing related for the same general purpose."