The Boat's serial number should be stamped on the rear starboard side of the transom, if it starts with the letters BDB its a 20' Blackman skiff. The serial (Hull) number should also be on the registration and Pink Slip just ask the owner. After seeing the link, that's no Blackman! At least not an 87. 1967 maybe ? Don & Shirley only had 1 son and 1 daughter And Steve never built anything by himself.