Application of floaters on mitigating snap load

Application of floaters on  mitigating snap load in umbilicals for deep water ROV operation



  • Steffen Remvik 

Project Description

ROV (Remote Operated Vehicle) is an unmanned under water vehicle that is connected to a ship or surface facility by an umbilical. In order to reach a deeper depth, an ROV needs to be lightweight, even neutrally buoyant, so the tension load in the umbilical does not exceed the safe working load of the umbilical. However, due to its lightweight, the ROV is easy to get disturbed by ocean wave and ship motion, hence can experience a series of snap load. Snap load is a large tensile force that occurs when a slack umbilical becomes taut. Snap load is an unwanted phenomena during an ROV operation since it can damage the umbilical or the ROV itself. Previous numerical studies in UWA show that a series of floater can be installed along the umbilical to suppress the occurrences of snap load by isolating the ROV motion from the ship motion. Before applying the approach to the real life deep-water ROV system, a physical test should be conducted to ensure the successful of the approach.

In this project, a scaled model of a deep-water ROV-umbilical system is deployed in the Swan River. The model consists of a cube box which represents the ROV and a thin wire representing the umbilical. Two different wire configurations will be deployed: a wire without any floaters installed, and a wire with a series of floaters. At the later configuration, the floaters are represented by a set of Styrofoam. To monitor the tension in the wire, two load cells are installed on the wire: one at the wire-boat connection, one at the wire-box connection. The number and location of the Styrofoam floaters are investigated numerically and experimentally for an optimized solution.