61-meter Superyacht "Just J's" Launches At Hakvoort Dutch builder Hakvoort launched one of their largest yachts this morning at their Monnickendam facilities. Now that she is launched, the 61-meter superyacht officially becomes the yard's largest build to-date. She was constructed as YN248 under the code name 'Golden Age'. However, her finished name and badge can be clearly seen displayed from her sides, "Just J's". The superyacht has Naval Architecture designed by Diana Yacht Design while the interior is by Sinot Yacht Design.