A start up meeting took place on the 28th September between ETP (Dr. Tom Davey), QED Naval and M.Eng Student, Steven MacKinnon who will be conducting experimental analysis on the stability and hydrodynamics of the Subhub during transportation, installation and operation within a wave and tidal environment.
Steven has just returned from a summer sabbatical with Xodus so we are confident that he is going to use this experience to the full and produce very useful results to take forward to a large scale prototype. The aim of the project is primarily to fulfil the requirements for achieving Steven’s M.Eng qualification but in doing so produce a scale model for laboratory testing using the facilities at Edinburgh University.
The geometry of the Subhub will be similar to the one produced from the initial sizing studies created by QinetiQ GRC but with some improvements integrating lessons learned from the original analysis. The model is scheduled to be completed by professional model builders by Christmas ready for tank testing early in 2013. It will be instrumented to provide validation of the numerical modelling that is due to be run in parallel to the tank testing as part of the Scottish Enterprise SMART feasibility study.
The UK IPO have just released the final notification that there are no further objections to the Subhub invention. We now have to wait 3 months before the patent could be granted. The reason for this delay is to give anyone who is interested in the application a chance to make observations on the patentability of the invention and to allow the search to be completed for documents published before the priority date of the invention. This is the final stage before granting the patent.
QinetiQ GRC have completed the initial sizing model of the Subhub and Turbine Module using their Paramarine software. It has concluded that both the Subhub main hull and Turbine Module would pass IMO and MCA stability standards. These results surpass all expectations at this stage of the development and provides a high level of confidence in forging ahead with the feasibility study. The next stage will review the dynamics and motion characteristics of the Subhub and Turbine Module which will explore the safe operating limits of these large marine structures to realistic environmental loads.
Below is the initial stability for the Subhub in its deployment role which includes the Turbine Module. It has a massive initial stability and peaks at approximately 15 degrees and remains positively stable until 80 degree heel angle.
To provide some feeling of how stable this platform is, below, is a picture of the GZ curve including heel angles that have been imposed from 100 knot gusts. It uses a tiny fraction of its 8.0 m GZ righting arm at just over 0.1 metre. This also suggests that it performs equally well on the seabed under turbulent tidal stream conditions.
Pictured below is the Turbin Module floating on both the light ship and with the main hull section flooded. This is the condition used for the maintenance and swop over of modules and are the waterlines used to tow it back to port.
The picture below shows the Turbine Module after it has been disconnected from the Subhub platform which remains firmly anchored to the seabed with over 1000 tons of ballast holding it in position.
Below is the initial stability assessment of the Turbine Module with all the tanks full and shows that it is very stable at the surface in this condition and capable of supporting more intrusive operations on the turbines generator or electrical conditioning equipment or towed back to port.
QED Naval has recently been awarded a SMART Grant from Scottish Enterprise to carry out a feasibility study on the Subhub concept. The work will assess both the technical and commercial viability of the platform and determine whether the business plan is achievable. The offer is conditional and means that QED Naval are looking for further private investment of between £50,000 to £80,000 in order to draw down on the Grant money.
Dr. Tom Davey from Energy Technology Partnership (ETP) will be supervising a M.Eng student project to perform some model tank tests on the Subhub operating in waves, submerging during installation and in service on the seabed.
QinetiQ GRC have just completed an assessment on the Subhub’s stability in the floating and compared it with stability standards used commonly within the marine industry. I pleased to announce that it surpassed all these standards with flying colours. Included within the assessment was a generic turbine with a payload of 150 tons elevated at approximately 25m above the Subhub main hull, not including self weight. It also included a payload of 300tons within the main hull representing all the switching gear, heat exchangers, pumps, on electrical transmission equipment.
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