Subhub Demonstration Trials Begin

QED Naval have completed the setup of the performance trials of the ballast system of the Subhub Community Demonstrator. The trials will take place over the next 3 months, initially situated at a sheltered water, low flow site in Castle Ward Bay. The conditions will be progressively increased in magnitude by moving offshore into deeper waters and higher flow rates.

QED Naval are being assisted by Cuan Marine who will conduct all the marine operations using the their 10m Multicat called “Cuan Cat”. Using this modest but highly effective work boat keeps the costs down. Cuan Marine are also providing a test barge for the Subhub Ballast Control Centre (BCC) and Subsea Manifold.

Subhub is unique in the manor in which in installs/recovers subsea equipment. It is more stable in the submerged or dive condition than it is in the transit condition. The net weight which causes the Subhub to dive is relatively small between 1 -10tons so the dive can be controlled easily and recovered quickly to the surface, within minutes.

Subhub has already proved itself in the transit condition having been deployed from Belfast to Strangford Lough which involved a passage ranging 50nm offshore in near gale conditions experiencing a sea state in excess of 2m in significant wave height.

Subhub has spent that last 3 months at sea experience the winter storms and freezing temperatures and it is clear that Subhub is coping well in its new habitat. There is 100% availability on all ballast systems and instrumentation which is testament to the design and quality of supply chain equipment.

However, it is clear that in the transit condition, floating at the surface, Subhub, like any marine structure, attracts significant marine fouling. This is a result of being at the surface in a relatively benign flow environment in pristine and fertile waters.

QED Naval have planned maintenance two times a year (April and October) to deal with the marine fouling issue and this plays to the Subhub’s strengths that it is easily and cheaply recovered for servicing the turbines and electrical equipment and maintenance of the hull structure. This may be reduced to once a year as the company learns more about the O&M requirements.

Setup of Cuan Marine’s barge to support ballast system and performance trials.

Subhub, umbilical and subsea manifold all secured on the mooring ready for installation/recovery.