The yearly 'vertrekkers' meetings organised by the magazine Zeilen might be more or less what you are looking for? They have a few seminars and meetings every year.
Once out in the blue you will find a Dutch 'club' in almost every anchorage, they are everywhere.
I thought Zeilen (Sailing) stopped organizing those meetings due to cutbacks. At least they didn't organize one this year. Zeilvereniging "de Toerzeilers" (Sailing Club "The Cruisers") did though. It was held on november 15th. 3 days ago. It's possible Toerzeilers has taken over the event.