The raft has 3 or 4 uses.
- troll the shore to explore, usually naked in case you die.
- cross visible shore to visible shore, short distances. usually naked, in case you die.
- explore the ocean far out, always naked, in case you die.
- recovering your stuff, after you died.

speed 1 is paddle, when the wind is unfriendly. It sucks on the raft, but its quite good on the karve (next boat class).
sailing like IRL works, where you go the wrong way left for a while then the wrong way right for a while to make a straight line using the edges of the wind. The game made the sails catch wind at a very generous angle so this is not difficult.

serpents are easily killed with a bow and a bit of skill. But they are too much for a meadows geared guy in a raft. Go get a karve from the forest, and upgrade your bow, and all these problems become non-problems. You went too far out to sea with too little equipment and a weak boat.

You can undo your death by restoring the .old character file. You will appear at the last place you were (probably at home or on shore) when you saved and with all your stuff restored. Or you can man up and fight your way back to your stuff. Your stuff does not float, but your body does, so you get it back. If you just toss it in the water, it will sink of course.

Good luck! Almost every one of us has died in a raft doing exactly what you did. Its part of the learning curve.