One thing we can know for sure, the island "moved". But to have some kind of force "move" and island through time and space would have to be strong enough to compensate for the magnitude of the island. We're talking a pretty big radius here. But how big?

Big enough to encapsulate or effect those few who were on the raft heading toward the boat perhaps. Since we didn't see them again, AND since we did see Dan in the past with more knowledge about the future that he should, perhaps those who were on the raft were moved through time and space as well. Maybe Dan knew about the orchid, knew about the mercenaries, knew about the importance of having a "constant" because he's looped through time many times. And this is the point at where he loops back.

But if that is the case then were the 6 who were in the helicopter far enough away to not be effected by the time/space rift?

Apparently the freighter was not far enough away to be influenced by the island, as evidenced by Mr. Shepard's presence on the boat right before the explosion.