Tracing history of a USCG / ASME vessel

[airtight]

I am requiring some of the original certification of a vessel built to ASME / USCG . It does not have a nat board number on it and was built in early seventies. It does have a uscg number on it though. I called the NB but they told me that the builders did not start registring reports with them until a couple of years after this vessel was fabricated . Can anyone tell me if vessels were recorded by the uscg at this time and if there is a way to get that information the same way as NB use? thanks in advance. neville