I have the boat key and the steering wheel, but it won't start, what am I missing?

You need a few more items and to open the gate in the tunnel (if you haven't done so). Check the escape guide for the list of things you need.

Spark plug and gasoline also padlock key

Have you added the gasoline and the spark plug if yes then I don’t know if not you find those and then put them in their places then it should work also get a padlock key and go behind the boxes in where the boat is open there and that opens the bars so you can exit