That happened to around 50 years ago when my scratch built plastic stern-wheeler sank on Rushmere Pond, Wimbledon Common, during its maiden voyage.
Despite my wife's valiant attempts by wading out into waist deep water it couldn't be found! She made a determined and valiant effort though!
Needless to say we are still together!!!
I have always wondered if anyone ever found it and what it's final fate was.
Anyway thanks for posting your arrival and so triggering that memory....hope you enjoy the site as there are a great bunch of people here with vast experience and experience.