THOR (Tension Hookup Operation and Retrieval)

Overview

The mooring system for Wave Energy Convertors (WEC) typically requires a degree of pretension in the system to achieve acceptable system responses, regardless of the mooring line type. Hooking-up (connecting) and disconnecting the mooring system whilst generating sufficient pretension is typically a complex marine operation requiring numerous temporary phases, which has a resulting  economic cost to the project.

The proposed innovation integrates off-the-shelf and bespoke hardware, and a novel marine operations approach to facilitate the mooring hook-up and disconnection operations for WECs. The approach is also deemed to be valid for other offshore floating renewable devices and perhaps more general marine operations also.

In essence, a bespoke tool will be developed that is temporarily installed between a mooring pennant connected to the WEC and a part of the pre-installed mooring system. The tool is deployed from a workboat, but once in the water is self-supporting. The tool will provide a self-reacting pull-in force between the parts of the system, such that the main mooring line can be connected whilst under zero tension.

The Stage 1 project assessed the feasibility of the concept by carrying out concept engineering and operational storyboarding. This led on to more detailed engineering design and dynamic operations simulations at Stage 2. Ultimately TTI see all marine contractors operating in the sector owning and operating numerous of these tools in a safe and economic manner to support the installation of WECs and development of the industry.