Communicating Approximate GPS Position on VHF Radio for Coastal Vessels
When coastal vessels, such as fishing boats, need to communicate their approximate GPS position to each other or to shore-based authorities like the Coast Guard, they rely on efficient and standardized methods. This article explains how to give an approximate position using VHF radio and the nuances of position reporting in degrees and decimal minutes.
Standard Position Reporting on VHF Radio
The Coast Guard in areas like Long Island Sound practices a specific method for reporting positions on Very High Frequency (VHF) radio. They report positions without explicitly mentioning degrees, minutes, and seconds, which streamlines the communication process in highly dynamic situations, such as during emergencies or in busy operations. Instead, they use a format that is both concise and comprehensible to all participants in the radio conversation.
Position Reporting Format
To report a position, the Coast Guard uses a format like this:
Position 41 tack 35 decimal 22 north by 039 tack 55 decimal 41 west
This format is straightforward and allows for quick comprehension:
41 is the degree of latitude. 35 decimal 22 is the minutes and seconds of latitude, where 35 is the minutes and 22 is the remaining seconds. 039 is the degree of longitude. 55 decimal 41 is the minutes and seconds of longitude, where 55 is the minutes and 41 is the remaining seconds. The words "north" and "west" indicate the direction of the latitude (north) and longitude (west).This method is efficient and clear, making it ideal for quick communications between vessels and between vessels and shore-based operators.
Degrees and Decimal Minutes (DDMMmm)
For more detailed position reporting, especially when degrees, minutes, and seconds are necessary, the format "degrees and decimal minutes" (DDMMmm) is used. This format allows for precise positioning, which is crucial for operations requiring accuracy within small distances. When using this format, the minutes are divided into 60 parts of a degree, making positions more accurate.
Example of Degrees and Decimal Minutes
For instance, in the position mentioned in the example:
Latitude: 41°35.0′22.0″ or 41°35.353′ (as a DDMMmm format) Longitude: 39°55.0′41.0″ or 39°55.683′ (as a DDMMmm format)However, when giving an approximate position within a small range, such as within 11 miles, the exact value of the seconds is not crucial, and decimal minutes provide sufficient accuracy.
Why Use Approximate Positions?
The use of approximate positions is particularly useful when the exact coordinates are not critical but speed is essential. For example, during an emergency, it might be more important to give a quick and clear indication of a vessel's location rather than precise coordinates. The approximate nature of this position helps in understanding the general location without the need for elaborate recalculations or precise determinations.
Advantages of Approximate Position Reporting
Efficiency: Quick and concise communication is crucial, especially in emergencies. Clarity: The format is universally understood, allowing for immediate comprehension without delay. Flexibility: Suitable for various situations, whether it's communication between vessels or reporting to shore-based authorities. Accuracy within Range: While not as precise as DDMMmm format, it is accurate within a small radius, such as within 11 miles, which is often sufficient for many practical scenarios.Practical Application in Coastal Operations
Growers, anglers, and other coastal operators benefit from mastering these methods. For example, when a fishing boat needs to alert other vessels about a specific location, such as the presence of a school of fish, they can use the VHF radio to convey the position in a straightforward and efficient manner. This allows for quicker coordination and response, enhancing safety and efficiency in coastal operations.
Conclusion
Mastery of VHF position reporting is an essential skill for all coastal vessel operators. By understanding and using the right formats, they can ensure clear and effective communication, thereby enhancing safety, efficiency, and coordination in their operations.