ROVs and Moonpools - An Operator’s Viewpoint

Abstract

Weather conditions limit the operation of an ROV from a support vessel in two ways. One of these limitations is the capability to launch and recover the ROV without prejudicing the safety of personnel or equipment. The other limitation being the inability of the support vessel to maintain station over the ROV due to weather induced forces increasing the vessels thruster demand above acceptable levels.

By operating through a moonpool in the centre of the vessel the effects of roll and pitch are minimised. By correct design of the moonpool. vertical water motion can be minimised thereby reducing snatch loads on the ROV. With the umbilical handling system through the moonpool the vessel may be orientated to optimise its sea keeping ability without regard to the position of the ROV.

Experience has indicated that a moonpool, coupled with a correctly engineered launch and handling system which positively locates and guides the ROV through the moonpool and surge zone, has increased the operational weather window by as much as fifty per cent over a conventional overside launch support vessel.