You can kill them with a bow from a karve before they can sink it. Be very careful not to shoot your own ship. Find 10 wood on a shore and you can repair it after if you got hit at all. With practice and sailing with the wind, they rarely get a hit.

I disagree about the longship. Its useful, but the karve is much more nimble. I use both, depending on what I am doing, but the karve more often, the LS only for hauling more stuff in deep water. Most of my exploring the karve gets into rivers or closer to shore and handles shallows better.