How can you choose the best position reference system for a dynamic positioning system?

1 Purpose and environment

The first factor to consider is the purpose and environment of your operation. Different PRSs have different strengths and limitations depending on the type of work, the water depth, the weather conditions, and the interference sources. For example, if you are working in shallow water, acoustic PRSs can be affected by noise, reflections, and multipath effects. If you are working in high latitudes, GPS PRSs can be affected by ionospheric disturbances and poor satellite coverage. If you are working near offshore structures, laser or radar PRSs can be affected by reflections and occlusions. You need to choose a PRS that suits your specific needs and challenges.

2 Accuracy and reliability

The second factor to consider is the accuracy and reliability of the PRS. Accuracy refers to how close the PRS measurements are to the true values, while reliability refers to how consistent and available the PRS measurements are. Accuracy and reliability depend on the quality and performance of the sensors, the signal processing, and the error correction methods. For example, GPS PRSs can improve their accuracy and reliability by using differential GPS (DGPS) or real-time kinematic (RTK) techniques, which correct the errors caused by atmospheric delays, orbital errors, and clock errors. You need to choose a PRS that meets your accuracy and reliability requirements.

3 Compatibility and redundancy

The third factor to consider is the compatibility and redundancy of the PRS. Compatibility refers to how well the PRS integrates with the DPS and the other vessel systems, such as navigation, communication, and power. Redundancy refers to how many backup PRSs are available in case of failure or loss of signal. Compatibility and redundancy depend on the interface, configuration, and diversity of the PRSs. For example, acoustic PRSs can improve their compatibility and redundancy by using different frequencies, ranges, and transponders, which reduce the interference and increase the coverage. You need to choose a PRS that ensures your compatibility and redundancy levels.

4 Cost and maintenance

The fourth factor to consider is the cost and maintenance of the PRS. Cost refers to the initial investment and the operational expenses of the PRS, such as installation, calibration, fuel, and licenses. Maintenance refers to the frequency and complexity of the service and repair of the PRS, such as cleaning, testing, and replacing. Cost and maintenance depend on the quality and durability of the PRS components, the availability and accessibility of the PRS suppliers and technicians, and the environmental and operational conditions. For example, laser or radar PRSs can have higher cost and maintenance than GPS or acoustic PRSs, due to their sophisticated and sensitive equipment and their exposure to harsh weather and mechanical stress. You need to choose a PRS that fits your budget and maintenance capabilities.

5 Regulations and standards

The fifth factor to consider is the regulations and standards that apply to your PRS. Regulations and standards are the rules and guidelines that govern the safety, quality, and performance of the PRS, as well as the certification, inspection, and audit of the PRS. Regulations and standards depend on the jurisdiction, industry, and organization that you operate under, such as the International Maritime Organization (IMO), the International Association of Classification Societies (IACS), or the Dynamic Positioning Committee (DPC). For example, some PRSs may need to comply with specific requirements for accuracy, reliability, compatibility, redundancy, or testing, depending on the DPS class, the vessel type, or the operation mode. You need to choose a PRS that meets your regulations and standards obligations.

6 User feedback and experience

The sixth factor to consider is the user feedback and experience that you can gather from your peers, colleagues, or experts in the field. User feedback and experience are the opinions and insights that you can obtain from other people who have used or evaluated the PRS, such as operators, engineers, consultants, or trainers. User feedback and experience can help you learn from the best practices, the common problems, and the practical solutions of the PRS, as well as the advantages and disadvantages of the PRS compared to other options. For example, you can ask for user feedback and experience from online forums, professional associations, or training courses, where you can find valuable information and advice about the PRS. You need to choose a PRS that has positive user feedback and experience.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?