Final answer:
A compass deviation check over water is a navigational process used to ensure the accuracy of a magnetic compass by comparing it against known headings or navigational fixes. Regular checks are conducted especially in open water to account for any errors caused by local magnetic fields, and findings are typically recorded for reference.
Step-by-step explanation:
A compass deviation check over water is an essential procedure typically associated with navigation, particularly within the field of geography, although it also has relevance to physics and engineering. This process involves verifying the accuracy of a magnetic compass by comparing the compass bearing with a known heading such as a true navigational fix. Compass deviation refers to the error introduced into a compass reading as a result of local magnetic fields, which can be caused by the ship's structure or electronic instruments. It's critical for navigators to check compass deviation regularly to ensure safe and accurate navigation over water.
Performing a compass deviation check is a straightforward process that should be done under specific circumstances for the best results. It is often conducted when there are no land references in sight, ensuring that the vessel is well away from any magnetic anomalies that might affect the compass readings. The process can be done at regular intervals or after any significant change to the vessel's magnetic environment, such as after installing new equipment.
When completing a compass deviation check, navigators will use a known heading, such as a GPS or gyrocompass reference, to ascertain the compass's accuracy. They will then steer the vessel on various headings and compare the compass readings with the known reference points to determine the deviation. This information is critical and often recorded in a deviation card or table for the navigator's reference during future voyages.
Nautical charts and navigational tools play an important role in helping to determine the true heading of a vessel. When conducting a deviation check, navigators can refer to nautical charts to find reference points and use navigational tools like a pelorus or azimuth circle to take bearings off distant objects with known positions. These bearings can help quantify the compass deviation.
In conclusion, a compass deviation check over water is a navigational procedure that ensures the magnetic compass readings are accurate and not affected by local magnetic anomalies. It’s essential for safe and precise navigation and should be conducted regularly or whenever changes to the magnetic environment are suspected.