The longboat could have been damaged since i never checked its health so that's on me.

The second karve, as i remember, was cap-sized/tipped over by a really bad combination of a large wave and a serpent attack. I had never before suffered a cap-size, didn't know it could happen.

The first karve that was destroyed had full health and went down in SECONDS from what i can remember just 2 attacks. I'm pretty sure there was no wave damage so it still seems like a mystery to me. There were no witches(rocks) nor was i near shallows. There is a chance i may have hit it with 1-3 arrows from draugr fang with obsidian arrows but could that be enough?