Subsea Deployment Vessel Tank Testing
SDS was founded in 2008 to develop a novel method of transporting and installing large subsea structures using a vessel of opportunity rather than a Heavy Lift Vessel (HLV).
The subsea industry is developing more complex fields in deeper water. Typically these involve deploying large structures in hostile environments which challenge the capabilities of existing installation vessels. The limited availability of suitable vessels, their associated costs, and the restricted operating windows in harsh environments can place significant constraints on project schedules and budgets. SDS Ltd.’s founders, Arnbjorn Joensen and David Paul, identified an opportunity to develop alternative installation methods.
Their Subsea Deployment System (SDS) utilises a deployment vessel (SDV) which consists of solid buoyancy modules mounted on structural steel frames. The amount of buoyancy is sufficient to render the combined SDV and payload slightly positively buoyant. The complete assembly is transported to site using a submerged tow, thereby avoiding the effects of the surface environment and also avoiding the need for an offshore lift. The system is also suitable for the recovery of subsea structures and is therefore suited for the growing decommissioning market.
With basic science behind SDS is established, the company recognised the need for a testing programme to provide proof of concept and necessary data to build on and plan for next stage of development.
SDS Ltd engaged with OGIC to identify appropriate University expertise and selected the Department of Naval Architecture Ocean and Marine Engineering at the University of Strathclyde to verify their technology.
The testing programme, undertaken in the tank facility at Kelvin Hydrodynamic Laboratory, examined the motions of the SDV and the support vessel at three water depths beneath a support vessel oriented in three vessel headings. The testing delivered validation and proof of concept as well as providing data for comparison with computer simulations.
“The SDS project was well suited to the excellent hydrodynamic test tank facilities at the University of Strathclyde’s Kelvin Hydrodynamics Laboratory (KHL). The project gave the KHL team an ideal opportunity to demonstrate our recently-acquired capability of simultaneously measuring the motion of both a surface vessel and a submerged vehicle using a state-of-art optical motion capture system”.
Prof Sandy Day, University of Strathclyde
“The test results met or exceeded those predicted by computer simulations and have successfully demonstrated that the Subsea Deployment System can be used to safely install or remove large subsea structures in rough weather using low cost vessels. The success of the project was largely due to the input from OGIC in identifying Strathclyde’s Kelvin Hydraulics Laboratory as an ideal testing facility and in organising the contractual arrangements between the parties.
The positive test results have increased the interest from decommissioning contractors and SDS is now being proposed as a low-cost alternative to conventional construction vessels.”
David Paul, Engineering Manager, SDS