From: Penguin Symbols Dictionary
A solid body, its weight holding the ship fast, the anchor was taken to symbolize firmness, solidity, tranquillity and faithfulness. it holds firm and steady amid the flux of the elements and comes to symbolize the stable part of our being, the quality which enables us to keep a clear mind amid the confusion of sensation and emotion.
As the seaman’s last resort in a storm, the anchor was frequently connected with hope, which stands as a support in the troubles of life.
The anchor also symbolizes the war between the liquid and the solid, the land and the sea. It puts a brake upon life when it becomes too stormy.