I would wear asbestos gloves working on that thing.
CYT is for Cobalt Yachts. Cobalt was in business from 8/6/2006 and went out of business on (5/20/2010) and didn't build sail boats.
Venture 17 is a 5.3 m monohull sailboat designed by Roger MacGregor and built by Macgregor Yacht Corp between 1968 and 1974.
How can the HIN show 1977 as the build year? It's possible the CYT was re-used by the Coast Guard, but that does not look like a factory installed HIN which is usually embossed in the gelcoat.