The analogy to the force applied to the keel of a boat is gravity. Angle the sail to increase the vector sum in the direction of the orbit, the mean distance from the Sun increases. Reverse the angle to decrease the vector sum in the direction of orbit, the mean distance to the Sun decreases. Remember that the light is reflected off of the sail, so the sum of the impulse is the sum of the incoming and outgoing vectors. As I recall, the optimum angle between the sail and a line to the Sun would be 35.3 degrees.
No, that analogy is more like sailing a raft in a straight river with an upstream wind. Raise the sail, you go one direction. Lower the sail, you drift with the water in the other direction. You still only have two directions to travel in.
You can change which radial you are riding on by using gravity of passing planets to change your direction, but once you are outside their influence you will either be heading directly away from or directly towards the Sun.
You can do the same maneuvers that current spacecraft use, where you do several loops around the sun to gain momentum. I don't dispute any of that. I just disputed that you can tack upwind with a solar sail like you can in a sailboat.
Nor can you carve banked turns in a Viper fighter ala Battlestar Galactica circa 1978.