I have only met one other person with an 18' Sterling jet hull. Supposedly they only made them in 1979 and 1980. They are uniquely identifiable by the little concave/convex/concave transistion lip a the rear of the bow, or what I would call the top of the "dash panel".

I've been told they were very close to a raysoncraft, but I have not seen a raysoncraft with these features.

 to a raysoncraft, but I have not seen a raysoncraft with these features.
Regarding Sterling boats. Had a 1979 twin step deck 21 ft. V drive , 454 chevy, TH 400 3 speed trans , Champion  gear box. Triple blue color. I currently have a 1979 two step day cruiser Eliminator.Same boat hull ( full stringer).