Category Archives: Demonstration

Trial Lift Readies Subhub for Quayside Launch

Transportation contractors, Mar Train, completed a trial lift of the Subhub recently to reduced the risks associated with the load out to the quayside at Harland & Wolffe, Belfast, Northern Ireland.

The weight of Subhub throughout the build has been controlled in order to achieve the load out requirements which were proven by the Mar Train test lift.

As a result QED have refreshed all their stability models to ensure compliance with each load condition i.e. load out, transit to site, installation and recovery, and in-service conditions. Damage conditions and reserve buoyancy have also be considered carefully.

Exit is planned early in the new year, shortly after, the Subhub will be launched for final ballast testing and then towed to site ready for installation.

This load out phase of the project demonstrate how a tidal power plant such as Subhub (210kW) can be fully integrated at the quayside and deployed, installed and recovered in a single, quick offshore operation. There are no other moorings to lay just a single dry mate connection to make to an export cable which is grid compatible.

Mar Train test lift carried out using their 7-axle trailer to reduce the risk of the exit from the fabrication shed.
Mar Train take up the full load and lift Subhub off the upstands.

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.

Subhub Nears Completion at Cimpina for EMEC Deployment


QED Naval and their selected fabricators, Cimpina based in Northern Ireland, are soon to complete the Subhub community demonstrator ready for deployment to EMEC in the next couple of months. Once at EMEC it is intended to use the FORESEA funding to conduct a phased set of sea trials to demonstrate that a tidal array can be installed and recovered in a single offshore operation using small vessel with low date rates.

  • Phase 1a installation and recovery trials at the scale tidal test site using replica turbines and equipment allowing marine operators to gain valuable experience of installation method.
  • Phase 1b aims to integrate Schottel Hydro SIT-250 turbines providing Subhub with a capacity of 190kW, capable of powering 50 homes. This collaboration includes SME who will be providing their ‘Flipper’ support structure for bi-directional flow, Platform Operation Module (POM), for controlling the platform at EMEC and Subsea Transformer Module (STM) to transmit the grid friendly power ashore.
  • Phase 2a will then move operations over to the Falls of Warness site. The aim is to demonstrate the installation and recovery over a wide spectrum of tidal flow and wave heights since the deployment method uses Subhub’s unique submersible stability characteristics that are less sensitive to extreme conditions.
  • Phase 2b will demonstrate the long term deployment capabilities, operational stability of its gravity based anchoring system and increased performance characteristics of the turbines which have shown insensitivity to cross flows in tank testing at Flowave. An O&M strategy will be developed for its customers assessing fatigue loads, marine growth and corrosion factors.
  • Phase 3 will be used to assess the environmental impacts of a longer term deployment and demonstrate the ability of the Subhub to be quickly and easily decommissioned from the site.

Once this testing is complete it is intended to offer the Subhub for sale and re-use it at another site. All going well Subhub will be further developed utilising a test berth at EMEC with a larger capcity machine rated at 1.2MW. QED Naval is in early stage discussions with several collaborative partners who would like to be involved in this larger scale development due to be deployed in 2018.

Hive of activity by Cimpina team at the aft end of the Subhub.
Project management team discussing the completion of the Subhub, pictured at the front end of Subhub.
Subhub side shell and aft leg of the tripod configuration of Subhub to maintain stability on an uneven seabed.


Subhub Completes High Flow Installation Trials

Successful Installation & Retrieval Trials in Real Tidal Conditions

Subhub TUC Tocardo Dummy Turbines
Subhub in transit condition whilst moored up in real tidal conditions after a passing squall brought waves up the channel. The white blade profiles simulate the rotors of the turbines during installation/retrieval.

Recent testing of the Subhub operations model in high tidal flow conditions proved its ballast system capabilities and installation and retrieval methodology with great success. QED Naval were able to install the model on the seabed safely and in a controlled manner within minutes. The model was then secured on the seabed overnight before being recovered to the surface gracefully within an equally short time period and control.


Despite onerous wind, wave and current conditions experienced during testing, the Subhub coped admirably during the installation and retrieval trials.  Scaling these extreme conditions to the prototype size, based on a 4.0m diameter turbine, would be equivalent to over 2m/s or 4 knots with a significant wave heights over 1.0m


Frontal profiles of turbine blades were added to the cross beam to simulate three turbines being installed on the Subhub; the blades acting against the current presented no issues.

Subhub Ops Model Weighs In

The Subhub Operations Model continues it fit-out and setup for the testing at Forth Estuaries Engineering’s (FEE’s) dock in Leith. An essential part of that was the “weigh-in” to check against our design calculations to ensure she is correctly ballasted for her initial trials.

The operations model is based on a 1.0m tidal turbine rotor diameter. It is designed to accommodate 3 of the heaviest tidal turbines on the market. The Operations Model has been built to the same mass proportions of the prototype so its motions will be accurately modeled.

The “Operations Model” is the 3rd in a series of models with very specific objectives. It has been developed to test the ballasting system and conduct installation/retrieval trials.

Subhub operations model combined with X-Beam being weighed and checked against design weight.
Subhub operations model combined with X-Beam being weighed and checked against design weight.

Pentland Precision Engineering Deliver Subhub Operations Model

Fabrication has been completed on the operational model of the Subhub at Pentland Precision Engineering allowing QED Naval to begin the pre-testing setup of the device. The Subhub looked magnificent in the Edinburgh Sun as weeks of work culminated in a device that will be tested to the limit by QED Naval. Over the next week the team at QED will be carrying out pre-testing preparations fitting extensive instrumentation and ballast systems to gain the most out of the coming testing phase.

Project team at Pentland Precision Engineering Gordon Hardman (left) Grant Middleton (centre) and Chris Scott (right).

Pentland Precision Ops Model Delivery

Aris Zavvos Joins QED Naval Team

QED Naval is proud to welcome a new member of staff into the ranks. Aris Zavvos who has recently joined us has a Sustainable Energy Systems Master degree and a PhD in Electrical Engineering from the University of Edinburgh. Aris has been recruited as the Electrical Systems and Turbine Integration Engineer to manage the electrical design and development of the Subhub tidal turbine foundation as well as validating the instrumentation and data acquisition system during the testing stages of our first prototype.


Full ‘Stream’ Ahead on the Subhub Tidal Turbine Foundation

QED Naval is delighted to announce that they have received the financial backing from Kelvin Capital and the Scottish Investment Bank this week to support the continued development of the Subhub, the tidal turbine foundation structure.

This 1st tranche of money will allow QED Naval to conduct the tank testing of 2 models of increasing scale within the world class, FloWave TT facility. These experiments will allow them to validate the current Subhub design against 3 principle objectives that include:

  • Verification of the design process and tools;
  • Provide evidence of the performance claims increased power output and;
  • Define the limitations from extreme loading events from combined wave and tidal forces.
Subhub validation model nearing completion.
Subhub validation model nearing completion.

Scottish Enterprise Award SMART Grant

It is a pleasure to announce that QED Naval have been awarded Scottish Enterprise, SMART R & D grant to support the ongoing development of the Subhub project.

This project aims to complete the validation, build and test of a large scale prototype of the Subhub. The overall goal is to demonstrate a large reduction in the cost of deployment of tidal turbines and validate the performance claims that show large gains in power output when compared with a typical tower installation.

Subhub Rapid Prototype Model

It may be small but the new model of the Subhub prototype really seems to bring the project to life. Built using the state of the art Selective Laser Sintering (SLS), 3D printing method, to tight tolerances required for the test tank models.

The tank testing will be used to validate design analysis carried out to date using our fluid modelling CFD software from ANSYS (Fluent). Verification of the drag forces on the Subhub and the velocities in way of the duct will provide confidence to go on to build the community scale prototype, capable of generating 600kW of energy into the national grid. The prototype is scheduled to go to sea in 2015, installed at the EMEC tidal test site in Shapinsay Sound, Orkney.

1st Subhub model to be produced.