No ferries. Use airlines.
Browse the Airport (Reina Beatirx) website.
At this page (link below)
http://www.airportaruba.com/en/flightinfo/departures/
you can view live departure times.
Much other useful information on the site.
Home Page is
http://www.airportaruba.com/
Some of the airlines that go to Curaco are ...
Tiara Air, Dutch Antilles Express, Insel Air ...
Inquire at the airport. Facing the buildings go to left hand
side (right side is for USA departures only).
hth