From Washington State Ferries:

On Wednesday, August 16, the Vashon 5:45 am to Fauntleroy and the Fauntleroy 6:10 am return to Vashon are cancelled due to overnight repairs to the propulsion system of M/V Issaquah, requiring sea trials in the morning. The Issaquah will return to service with the Vashon 6:40 am sailing to Fauntleroy upon successful completion of sea trials. We apologize for any inconvenience. Updates will occur as more information becomes available.