Lol yep I tend to cut things close xD
And yeah I used vector calculations from physics for this. First there is a vector from the object's position to the center that pulls objects inward at a constant velocity, then there is a perpendicular vector to that one which is used to apply the angular velocity which increases the closer you are to the center. The boat thrust is just a constant acceleration applied based on your angle (using sin and cos), and is calculated separately from the maelstrom velocities. Thanks for asking!
As far as the weather theme goes, I knew I wanted to do an Asteroids-like game at sea where you're caught in some sort of storm. Then I had the idea for the maelstrom which I totally thought was a weather phenomenon...