'It is said that Amandil set sail in a small ship at night, and steered first eastward, and then went about and passed into the west. And he took with him three servants, dear to his heart, and never again were they heard of by word or sign in this world, nor is there any tale or guess of their fate. Men could not a second time be saved by any such embassy, and for the treason of Numenor there was no easy absolving.'
I believe Amandil was too great a mariner to be lost at sea. He probably was caught in one of the guarding isles; Earendil was the only sailor to ever reach Valinor, and this was because he had the Silmaril with him. I believe in one of the HoME there is a fragment of a tale of a mariner who landed on the isle of the elves and drank their wine, becoming immortal. I don't remember if it was in the Lays of Beleriand, Unfinished Tales, Lost Tales, or where. However, this was written when Tolkien intended to morph the history of Middle-earth into the history of Earth.
Perky, this quote comes from the hiding of Valinor: "And in the twilight a great weariness came upon mariners and a loathing of the sea; but all that ever set foot upon the islands were there entrapped,
and slept until the Change of the World."
Rip Van Winkle, anyone?
