Encountered my first Serpent while sailing around an island in my karve to get to one of my bases. Luckily, I wasn't too far from shore, and had a good onshore wind. I tried to tack at the last second to get him to miss the boat, but not sure if it really helped.
In another stroke of luck, I was able to wedge the karve up between a large rock and the shore where the Serpent couldn't get to me. I received one final blessing from the gods when a squad of Greydwarfs came boiling out of the forest and jumped into the water to attack the Serpent.
It was total chaos as the Serpent looked like it was tying itself into knots to get at the dwarfs while they were all standing chest deep in the water to swing at it as it passed by them as the shaman healed them. (I tried to help by shooting fire arrows, getting four hits.)
After taking out all the dwarfs, the Serpent decided it had had enough, and headed back to deep water. I repaired the karve and made it home without further excitement.
My only regret over the whole adventure was that I hadn't been recording the game.