Marine library
Ionospheric Delay refers to the time delay experienced by satellite signals as they pass through the Earth's ionosphere, a layer of the atmosphere filled with charged particles. This refraction alters the speed of the signals, leading to positional inaccuracies in GPS and other Global Navigation Satellite Systems (GNSS).
An Inertial Navigation System (INS) is an advanced navigation tool that uses accelerometers, gyroscopes, and algorithms to determine a vessel's position, velocity, and orientation without relying on external references like GPS. INS is particularly valuable in Dynamic Positioning (DP) and offshore operations, offering a reliable backup or complement to satellite-based navigation systems.
Independent Joystick Control is a standalone control feature in Dynamic Positioning (DP) - capable vessels that allows the manual operation of multiple thrusters using a single joystick. This system operates independently of the DP system, providing a reliable backup and added flexibility for vessel control in various scenarios.
IMO MSC Circular 645 is a foundational document published by the Maritime Safety Committee of the International Maritime Organization (IMO). Entitled “Guidelines for Vessels with Dynamic Positioning Systems”, this circular establishes standards for the design, operation, and redundancy of Dynamic Positioning (DP) systems used in maritime and offshore operations.
The International Maritime Organization (IMO) is a specialized agency of the United Nations responsible for regulating shipping on a global scale. Established in 1948 and headquartered in London, the IMO plays a pivotal role in promoting safety, security, and environmental sustainability in maritime operations.
In Differential GPS (DGPS) systems, the Hub refers to the central master reference station within a network of multiple reference stations. The hub plays a pivotal role in ensuring the accuracy and reliability of positional corrections by serving as the central processing and communication point for the network.
Hydroacoustic Position Reference (HPR) is a position reference system widely used in Dynamic Positioning (DP) operations, particularly for subsea and deep-water activities. This system relies on acoustic signals transmitted and received underwater to determine the vessel's position relative to fixed or moving subsea reference points.
Heave refers to the vertical movement of a vessel in response to external forces such as waves, tides, or loading changes. It is one of the six degrees of freedom in a vessel's movement, alongside pitch, roll, yaw, sway, and surge. Heave is a critical parameter in maritime operations, particularly in Dynamic Positioning (DP) and offshore environments, where maintaining stability and precision is essential.
Heading Priority is a feature in the positioning algorithm of a vessel's Dynamic Positioning (DP) system that prioritizes correcting heading deviations over positional deviations. This function is particularly useful in operations where maintaining a stable heading is critical, even if minor positional errors are temporarily tolerated. In some DP systems, Heading Priority can be selected or adjusted by the operator based on operational requirements.
HDOP (Horizontal Dilution of Precision) is a key metric used to assess the accuracy of GPS and DGPS systems. It reflects the impact of satellite geometry on the horizontal positional accuracy of a GPS receiver. Lower HDOP values indicate better accuracy, while higher values suggest reduced reliability.
