If transportation happens in this game, you're gonna need something to move the raft.
First of all, power.
You need to make engines (scrap + ???) and place them on the edge of your ship so that it can move.
The more things your raft has built on it, the more engines you'll need. (Maybe you can make more efficient engines?)
Then, you need something to drive it. I think a helm would fit. With rope and planks. Place it, and have enough power to move your raft, and you're off!