The 16SL was made from 1990 to 1994. For those years the builder, Boston Whaler, was required to attach a federal hull identification number to the hull in a permanent manner (including in some instances by molding the hull identification number into the actual gel coat resin of the hull). If the 16SL boat has been properly maintained, this federal hull identification number should still be attached.
Look for the number to be molded into the hull or to be embossed on a metal tag and located on the transom. Much more information about federal hull identification numbers and how they can be interpreted is given in the FAQ. Read the article linked below carefully:
Q2: where is the federal hull identification number?https://continuouswave.com/whaler/reference/FAQ/#Q2Also refer to the document linked below to find the specific production sequence five-character identifier for the 16SL (beginning at DA000).
HIN production number sequences by hull modelhttps://continuouswave.com/whaler/refer ... quence.pdfRegarding any sort of documentation containing certificates of compliance with regulations of your country or with the European Union, I doubt that in the period of the manufacture of this hull there probably were no European Union regulations to be complied with because that entity did not start until November 1993. I doubt they instantly promulgated import regulations for small fiberglass boats. It probably took the EU Commission on Importation of Recreation Small Boats a few more months to figure out what new ways they could impede the sale of boats made in the USA to consumers in Europe by creating rules and paperwork, and thus protect the European boat builders from competition from the USA.