Ship Launching Question

[Guest]

I have noticed that in pictures of ships being side launched that they are in various states of construction. As such, some are launched as little more than hulls while others have their cabins already in place. This extends to ships that share nearly identical designs. For example, the Edmund Fitzgerald was launched with just a portion of its after cabin structure in place and no forward cabins while the Arthur B. Homer was launched with what appears to be all of its cabins in place. It seems logical that the differing weights involved at various stages of construction would affect the measures necessary for launching such a large object, often into a confined area. Is there any reason as to why ships are launched at various points in their construction? Is it dependent upon the need to free up the building ways for the next contract? My question is in relation to the side launching of Great Lakes ships and not those launched in dry docks.