During hours of darkness, every vessel shall be equipped with and, while underway or at anchor at any place other than a dock or shoreline, shall display navigation lights as hereafter prescribed. Such lights shall be a white light which shall be temporarily exhibited in sufficient time to prevent a collision; PROVIDED, That any motorboat while underway shall continuously display a white light distinctly visible for a distance of at least 500 feet; and PROVIDED FURTHER, That it shall be deemed a compliance of this section when any vessel displays navigation lights of a type approved by competent authority for operation of such vessel in inland waters. (Added by Res. adopted June 30, 1975).