A course is set through the middle, side thrusters, rudders, and|or engines fail or falter, and current drifts the ship into the bridge pylon.

Ships in water tend to move and keep moving, engines and thrusters work to vector that motion into a desired direction - when things fail motion doesn't cease and courses aren't maintained.

The ship, most of its lights go out a minute of two before the collision, and it also seems to be emitting black smoke (from the funnels / engine exhaust?) as well.

The lights on the ship all go out about 5 minutes before impact. They come back on and appear to go out again as impact gets closer. It looks like the ship suffered a catastrophic failure that affected the controls.