A magnetic compass should align itself steadily to the earth’s magnetic field, pointing to magnetic north. However, when the compass is installed on a boat, metals and electrical equipment may cause magnetic fields that distort the earth’s field at the compass location. The effects of these onboard magnetic fields change with the vessel’s heading. The difference between compass north and magnetic north on the different headings is called the deviation. Compass adjustment is the compensation of these deviating forces with magnetic correctors. For various reasons such as design, location and practical expedience, all the deviation may not be removed. The residual deviation is recorded as a table or a curve of deviation against the compass headings.
Ocean Ireland delivers yachts and powerboats for private owners, brokers, charter companies and boat builders.
A Marine Surveyor is defined as:
“A person who uses their skills and experience, (based on established competence of ships, boats, cargoes and the sea) to look at and report on the factual condition of any ships, boats, cargoes or thing appertaining to ships, boats, cargoes and their respective environments” (International Institute of Marine Surveying) ”
- After periods of lay up.
- When a new compass is installed.
- When deviation exceeds 5 degrees.
- On a new vessel or in a new area of operation.
- After trauma, such as lightning strike, grounding, fire, etc.
- When compass performance is unsatisfactory or unreliable.
- When a record of compass deviation has not been maintained.
- After alterations and additions to the vessel’s structure and equipment.
- After repairs involving welding, cutting, grinding, etc. which may affect the compass.
- When electrical or magnetic equipment close to the compass is added, removed or altered.
- When compass deviation does not appear to correspond with that shown on deviation card.
Anywhere… Oceanwide….Worldwide & Local.
A marine surveyor is highly recommended if you are considering buying a new boat. The surveyor will give you an objective, factual opinion of the condition of the boat. It is not unusual for a client to save the cost of the survey many times over when negotiating the price based on the survey report.
A survey is also required for insurance purposes.
The magnetic compass is an essential navigational instrument. On the water, knowledge of direction is of vital importance, especially when visibility is poor or visual clues of direction are not available. A correctly functioning magnetic compass shows the vessel’s heading. The magnetic compass is independent of power supply, making it a most reliable navigational instrument. The compass is also a key tool for determining the risk of collision (Colregs rule 7).
Extensive… Ocean Ireland skippers have been delivering vessels oceanwide for over 25 years.
In a typical sailboat purchase, the buyer of the boat pays for the survey.
GPS has a built in electronic compass. However it only works when you are on the move. A GPS requires satellite signals and electricity to function. It is an excellent tool but power failure or electronic break down renders it useless.