They built C-larks which is a 14' fiberglass version of an International 14, that never quite made it to the big leagues speed wise, but VERY populare 1d class for many years. IIRC they built some fiberglass tbirds too. I was in my teens and before, so do not know what other boats they built in the 10' range etc.
not sure if you found this, but here is the general story in pd from the SJ21 assoc. I think it may have been linked first on an SJ28 group, but do not quote me. I see they did some other dighys too excert below
The Clarks had moved to the Seattle area from Toledo, Ohio in the early 1960’s to start
a fiberglass boat building business. While Coral worked as a nurse supervisor, Bob set
about making the Clark Boat Company into a viable business. The three sons, Don,
Dave and Dennis, were busy attending school, but found time to help out whenever they
could. The first boat with the “Manufactured by Clark Boat Company” label affixed to it
was a Lightning, and it was one of the first fiberglass lightnings on the market. They
also built OK dinghies, 505’s and Clark Star class boats took first and second in the
World’s in 1970.