Category Archives: Manufacture

Build of Subhub and all the components like the X-beam, Subsea Manifold, Replica Turbine Operating Module, Subsea Transformer Module, Platform Control System

Subhub Completes Commissioning

QED Naval have completed the commissioning of all onboard ballast and instrumentation systems ready for testing and launch early in 2018. This community version is a big step to proving the claims about competing with offshore wind for CFDs at utility scale.

QED Naval is working with Schottel Hydro on this 190kW version which is competitive, in terms of LCOE, with diesel generation for island communities’ or offshore power generation for aquaculture offering excellent niche market opportunities recently forecast by Aquatera.

However, Subhub was always designed for utility scale projects, removing the requirement for large specialist vessels at expensive day rates and multiple marine operations offshore. Where Subhub requires only a single offshore operation using smaller vessels and/or barge at low day rates.

Fundamentally, the concept of Subhub using buoyancy and good submerged stability to install the turbines scales very well. Also, the ballast ratios, for the required on-bottom weight to secure the turbines on the seabed, scales in their favor. The utility version is more slender and uses simpler construction methods reducing fabrication costs still further enabling the acceleration effects of the semi-duct to be applied to every turbine. QED’s latest CFD models when combined with a tidal harmonic models for the site and power curve of the tidal turbine show increases in yield of up to 50% year on year when compared with typical monopile structures. Subhub effectively increases the capacity factors of the site.

An independent report by a Master Mariner has stated that installation and recovery costs of a utility scale Subhub can be reduced by 50 to 90% compared with current methods. The seaworthy design, stability when submerged and the control of the ballasting process make the Subhub less sensitive to wave loading during installation. This allows it to be installed and recovered over broad weather windows and hence the availability for maintenance is higher. This attributes a large reduction in maintenance costs.

QED Naval pride themselves on the understanding of the combined effects of wave and tidal loading learning huge amounts from their tank testing at Flowave, open water testing at The Underwater Centre in Loch Linnhe. Their collaborations with EMEC/FORESEA, and QUB as part of the Tidal Turbine Turbulence (TTT3) project have provided unrestricted access to real measured tidal data using ADCP systems for accurate tidal modelling and turbulence measurements. QED’s work on turbulence modelling in collaboration with the National Oceanographic Centre (NOC) is thought to be class leading and provides more assertive results for energy yield calculations.

All this learning has been combined into Monte Carlo simulations for various projects QED have assessed which provides a sound basis to presenting the LCOE figures and making project finance decisions.

All these claims will be assessed in the next stage of testing to be commenced early 2018.


Aft view of Subhub showing tripod leg structure and semi-duct for accelerating the tidal flow into the turbine.


Subhub Gets Lift Off

QED Naval are pleased to annouce the acceptance of the Subhub – Kraken’s main hull fabrication including all outfit hotwork.

An important part of the acceptance was the main hull lift off the cradle and supporting structure onto the Subhub’s main leg structure to fully support her ample weight.

Factory Acceptance Tests (FATs) which pressurised each of the ballast tanks were completed successfully along with all the load testing of the lifting equipment including the main hull lifting lugs (68t load) and the modular solid ballast blocks (2 off) each weighing 20t.

All the welding plans and Non-Destructive Tests (NDTs) have been completed and approved.

QED Naval would like to take the opportunity to thank their prime contractors, Cimpina, in their support and commitment that they have provided to get the project to this point of completion.

QED Naval have now taken responsibility for all the outfitting of the Subhub and has completed all the internal outfit. Kraken is now awaiting painting which will be completed in early October.

QED Naval are currently commissioning and testing all the ballast and instrumentation systems prior to a planned launch in early 2018.

Subhub aft end showing the semi-duct that accelerates the flow into the turbines for increased power output and yield.
Subhub undergoing FATs pressure testing where each tank is pressurised to ensure water tightness and hydrostatic load capability.
The power of buoyancy! Amazing to think that this small compressor can lift almost 200 tons from the seabed in such a stable way over such large tidal and wave weather windows.

Cimpina Awarded Subhub Build Contract

Cimpina based in Northern Ireland in Belfast Docks have been awarded the build contract for the Subhub. They were among 6 different fabricators contending for the business.

Work commenced in November and the outer shell was taking shape before Christmas. Completion is expected in the first quarter of next year.

Keel Laying Team with Toasts of Scapa (Orkney Whiskey) and Champagne.
Keel laying ceremony with representatives from Cimpina * QED Naval toasting the commencement of build using of Scapa Whiskey (Orkney water of life).

The Community Subhub with a capacity of 200kW using Schottel tidal turbines will be launched and transported up to EMEC where long term testing will be conducted, as part of the FORESEA project, to demonstrate the Subhub’s capabilities with installation and retrieval. The performance of the Subhub and turbines will be monitored. Long term operations and maintenance strategy will be developed to validate the OPEX cost model and hence the LCOE for a Subhub related project.

External shell and bulkheads taking shape.
External shell and bulkheads taking shape.
Outer shell supported by the upstands.
Outer shell supported by the upstands.