Follow target mode on modern ships equipped with dynamic positioning (DP) system

Abstract

The article highlights the results of studying the follow target mode on board the ships equipped with dynamic positioning (DP) systems. There is analyzed the position of a ship in a follow target mode when the DP mode is on, as well as the ability of a ship following a target to hold the position and course under given environmental conditions. Ships equipped with the DP system have strict requirements regarding the parameters of the follow target mode. There are listed the advantages for specific operations: technical servicing the oil and gas fields, examining the pipelines, hydrographic surveys, etc. Functionality of the hydroacoustic reference system, which is the main component of the ship follow target system, is studied. It has been stated that the follow target mode allows the ship to follow the target automatically. In most cases, the target is an unmanned remotely operated vehicle (ROV). ROV is a robot performing specific tasks under water controlled from the ship. ROV support vessels specialize on such operations. The ROV equipment and capabilities depend on the complexity of the task. The simplest tasks are inspection of the pipeline, platform supports, watching divers, visual inspection of an object lowered to the bottom, etc., when ROV is equipped with cameras, searchlights and, occasionally, sonars. To carry out the construction work or maintain the underwater facilities there are needed the servicing ROVs equipped with tools for specific purposes. There has been illustrated a model chart of the ship motion and dislocation of the ROV working area. Connection between ROV and the ship by means of a fiber optic cable is considered in detail, the advantages and disadvantages of this connection are listed. Conclusions are drawn about the widespread use of DP systems on modern ships, in particular those operating in the oil and gas industry, as well as in other areas of marine operations.