Dear bump,
As much as I hate saying this (and really, I do), you should have read the FAQ. Also, the point about how traveling around can not prove the Earth is round has been covered in so many threads as to be embarrassing. The point is, if you always head towards the West, and that is to the left of the magnetic North, you are moving in a circle on a Flat Earth around the North (magnetic) Pole. You would have to do it on two different paths and compare their lengths to convince yourself whether the Earth is flat or round. Unfortunately, Magellan died on his first voyage, so a second expedition was never undertaken.
BTW, I am a Round Earther!
EDIT:
Come to think of it, there is a discrepancy between the two models in one particular case. Imagine going South. According to the Round Earth model, you will be moving along a meridian and eventually get to the South Pole. But, according to the Flat Earth model, you are moving in a radial direction on a Flat Earth away from the North (magnetic) Pole and eventually hit the infamous Ice Wall, and, maybe, get captured by the guards. So, what ever you do, don’t go South for a long time. Maybe, there is no Bermuda triangle. All they did was hit the Ice Wall and they were gone!