I usually build a dock similar to this video (although without a roof) to aid in embarking and disembarking without my boat skipping away to the horizon.
To embark: hop in the boat, open the doors, and sail away. When you return, sail in, close the doors behind you, and hop out. It just takes some practice to get in and out of one properlywithout landing in the water, but I've never lost a boat with this setup.
![Simple Boat Dock](https://i.sstatic.net/mTbKt.png)