Properly adjusted magnetic compass is a SOLAS requirement

Compass adjusting

Our Compass Adjusters hold MCA of competency and are available to adjust compasses in most ports in the UK.

Despite the move towards complete electronic bridges on board vessels, the magnetic compass still remains a very important aid to navigation. The Magnetic Compass operates independently of the other systems on board.

As long ago as the 15th century, mariners had noticed that the needle of a magnetic compass does not point accurately to Earth's true north. This is due to the variation of the earth’s magnetism. Compass deviation can also occur due to the ship’s steel body, type of cargo carried, electrical appliances, electronic instruments, and equipment etc.

The compass adjusting aims to nullify the effects of the various magnetic fields by placing corrector magnets adjacent to the compass enabling it to align correctly.

“Swinging the ship”, as the compass adjusting is sometimes called, involves the adjuster sailing with the ship to open waters and comparing the compass headings with actual known bearings. The difference between the two is called the deviation.

SOLAS Chapter V Regulation 19 requires a ship’s Standard Magnetic Compass to be properly adjusted.

ISO 25862: 2009 (E) requires the Magnetic Compass to be adjusted:

  1. No less often than intervals of two years
  2. After dry-docking
  3. After significant structural work
  4. When they are first installed
  5. If they become unreliable
  6. When repairs or structural alterations have been made to the ship that could affect its permanent and / or induced magnetism
  7. If electrical or magnetic equipment close to the compass is added removed or altered
  8. If the recorded deviations are excessive or when the compass shows physical defects or
  9. At any other time deemed necessary by the Master for the safety of navigation

Some Administrations require annual Adjustment for specific vessel types and annual Adjustment is sometimes advisable to prevent delays at some locations.