The passenger, who is understood to be a woman, went missing during a journey by the Condor Rapide fast ferry on Sunday afternoon.
The boat's captain raised an initial alarm with the coastguard and a full search of the vessel was conducted.
But she was still not located and the alert was upgraded to a Mayday.
The ferry searched the area, with the Portland Coastguard coordinating the operation. A helicopter was also scrambled.
Nigel Robson, Portland Coastguard Watch Manager, said: "We have searched the route of the ship and the areas where our search planning expertise indicate a person might have been carried by the tide. Sadly we have found no-one.
"It's now been five hours since the person was reported missing and because of the water temperature and difficulty of searching in the dark we have now called off the search." Read More