You can push a longboat as easily as a Karve. You can park either ship a couple meters from the shore and wade in to shore or if you stopped at an angle you can take a running start from a longboat, jump, and land dry footed on shore.

Once the ship stops moving it won't drift even when there are waves. A friend of mine that quit playing was sailing in his Karve and got attacked by a sea serpent. He jumped out of the boat about 50 meters from shore and tried to swim to get away from the sea serpent but got killed. Its been over 1,000 game days since he abandoned that karve and its still there floating 50 meters off shore not having drifted even a single meter from the point marked on the map.