Everybody onboard a ship understand the importance of knowing the ships true heading. In an emergency the magnetic compass may be the only source of finding the shortest way to the nearest port. Therefore SOLAS Ch. 5, Reg. 19.2 states: "All ships, irrespective of size, shall have a properly adjusted standard magnetic compass to determine the ships heading with means of correcting heading and bearings to true at all times". This means that if there is a magnetic compass onboard the vessel it has to be adjusted and a deviation card has to be prepared. The deviation of the compass shall be established bi-annually and if the deviation exceeds 5 degrees the compass shall be adjusted.