DaveW
The lifejacket won't affect getting into the raft. If you are in the water, and the raft isn't tied to the aircraft, you probably aren't going to make it into the raft, especially if you are wearing a life jacket.
Any significant wind is going to blow an empty raft along the surface faster than any sub olympic class swimmer can go after it.
The objective is to attach the cord to the aircraft (e.g. the yoke), then with the raft package outside the aircraft, pull the cord out until the raft starts to inflate, then get into the raft while its cord is still attached to the aircraft.
The cord has a breakable link in it which supposedly prevents the sinking aircraft dragging the raft down (but I carry a knife for this purpose anyway).
If you chuck the raft into the water, hoping to climb into it, it will just float away. Unless there is zero wind, which is rare.