The ss22 site has a lot of info;

www.spacesailer22.org.au/the_ss22/index.html

There are some prior forum threads on ss22 eg below - see also Microbe thread on his deck and chain plate repairs.

www.seabreeze.com.au/forums/Sailing/General/Spacesailer-22-fiberglass-fixing

The below thread includes some construction details - dated 31/5/85. Resin type not mentioned. The S22 was built from 1975-90.

websites.mygameday.app/get_file.cgi?id=2726911

Have done a quick search trying to find when vinyl ester resins started to be used in boats - hard to get a good article. I would have guessed around 1985. This patent is dated 1980 so 85 could be a reasonable estimate.

patents.google.com/patent/US4310644A/en

If the SS22 was built 75-90 maybe the latter boats could have been vinyl ester but probably the 75-85 boats were polyester. Someone on the SS22 org site might know?

Does it have a square hatch or a round hatch?