Neptunus is a 30-foot sailing yacht and the first generation polyester sailing yachts which C. van Lent & Zonen built around the 1960’s for an American client. The series were called Tripp. Also a series of a larger type, Javelin, of the same designer William Tripp were build. Around 10-15 of each were built. The polyester hull and superstructure were produced at Werkspoor in Utrecht. The carpentry and the installation of the engine were done at the Kaag.