December 2024
In Dynamic Positioning (DP) operations, Sea Current refers to the horizontal movement of water experienced by a vessel, characterized by its set (direction) and rate (speed). While sea current cannot be directly measured by onboard systems, the DP system calculates an estimated value through mathematical modeling.
Short Baseline (SBL) is a type of Hydroacoustic Position Reference (HPR) system used in Dynamic Positioning (DP) and subsea operations. The SBL system determines the position of a vessel or underwater object by measuring the distances between a series of hydrophones mounted on the vessel's hull and a transponder located subsea.
An ROV (Remotely Operated Vehicle) is an unmanned submersible used in a variety of underwater operations, typically controlled from the surface via an umbilical or wireless connection. These versatile vehicles are equipped with cameras, manipulators, sensors, and tools, enabling them to perform tasks in environments that are hazardous or inaccessible to divers.
Roll refers to the angular rotation of a vessel around its longitudinal axis (running from bow to stern). It is one of the six degrees of freedom in vessel motion. While Dynamic Positioning (DP) systems do not control roll, they continuously monitor it to ensure safe and stable operations, especially during challenging sea conditions.
A Riser Angle Sensor is a specialized device used on deep-water drillships to monitor the directional differential angle between the wellhead structure and the adjacent lower section of the riser. This sensor provides crucial data that ensures the drillship maintains its optimal position relative to the wellhead, protecting the riser system from excessive stresses caused by misalignment or environmental forces.
A Responder is a type of transponder used in subsea and Dynamic Positioning (DP) operations where the interrogation signal is transmitted via a hard-wire connection rather than acoustically through water. This setup ensures faster, more reliable communication between the DP system and the responder, especially in environments where acoustic signals may be affected by interference or signal degradation.
A Reference Station is a critical component of the Differential Global Positioning System (DGPS), providing correction data to enhance the positional accuracy of user vessels. These stations are located at fixed, known positions ashore or on offshore platforms and continuously monitor satellite signals to calculate and transmit differential corrections.
The Reaction Radius, also referred to as the Operational Radius, is a parameter in Dynamic Positioning (DP) systems that defines a circular area around a mobile target. This term is primarily used in Follow-Sub or Follow Target modes to determine how far the target can move within the defined radius before the DP system initiates vessel repositioning to maintain alignment.
Radascan is a short-range position reference system that uses Frequency Modulated Continuous Wave (FMCW) radar technology to provide precise positional data for vessels operating in dynamic environments. It is a critical component in Dynamic Positioning (DP) systems, particularly in offshore and near-platform operations where high accuracy is essential.
Push-Pull Mode is a propulsion technique used in Dynamic Positioning (DP) systems for twin-screw vessels. In this mode, one propeller operates in a continuous ahead motion, while the other operates astern. The thrust required for the vessel's surge movement is controlled by varying the rpm (revolutions per minute) and/or pitch of both propellers.
