Daniel said to think of the island like a record. Well i do...kind of.
The island spins very very fast. It distorts the light around it, making it not visible as well as creating a time discrepency inside and outside. This accounts for the payload and the doctor washing up.
You can cut right through the spin and get to crash right into the island but we know about the side effects and time discrepencys. or you can follow the right bearing and travel with the light moving with you, this will keep you in line with the real flow of time
But there are different degrees or speeds of spin, all controlled by the wheel. The wheel adjusts the spin making it visible only at specific bearings that the light run around on. Think of a corona around a black hole.
polarity is a big piece of lost i wonder if theres an "up spin" and a "down spin" aspect similar to quantum mechanics