Most likely there will be no white tie evening gala on April 30th.
The day events concentrate in Amsterdam's historic inner city: the Royal Palace (where the Act of Abdication will be signed) and the Nieuwe Kerk (where the new King will be invested).
The evening events will concentrate in two modern parts, the EYE, where the water tour will start and the Muziekgebouw aan 't IJ where it will end. In that last building there will be an evening program and most likely it will be black tie, not white tie.
In 1980 the royal guests were entertained on a ship and that was no white tie affair either.