First Tidal Stream Installation Ship Being Built For Pentland Firth

24th May 2013

New updated sketch 'renderings' of the World's first purpose-built tidal stream turbine installation ship, the planned HiFlo-4 catamaran vessel, have just been released by her designers Mojo Maritime Ltd, of Falmouth, Cornwall, one of Britain's most technologically-innovative 'green' marine energy specialist engineering companies.

Its managing director Captain Richard Parkinson has told Gills Harbour Ltd's chairman that its innovative vessel is on track for being delivered from her builder's shipyard during the summer of 2015.

The experienced mariner-turned-entrepreneur, who is familiar with winter sea conditions in the Pentland Firth and off the North of Scotland, has previously stated that Gills Harbour is his company's preferred Caithness base for HiFlo-4, hopefully by 2016.

The release of the HiFlo-4 drawings for this week's All-Energy event in Aberdeen comes just as Pentland Ferries Ltd has received the go-ahead from the Scottish Government's Aberdeen-based Marine Scotland agency for a major upgrade at Gills Harbour.

The 'marine planning consent', which was applied for just over one year ago, covers a 60 metre extension to the existing main breakwater/berth at Gills, plus a 100 metres x 100 metres dredged ship 'turning circle' in waters sheltered from the North West by the above.

The extension will be 'offset' to allow vessels involved in marine renewables operations to be berthed without interfering with scheduled ferry movements. As with the previous 116 metre-long breakwater/berth, the extension will be a recycled one-time floating dry-dock, with Caithness flagstone rock-spoil from the dredging operation being used as ballast, so avoiding 'dumping at sea' adversely affecting wild-life in Gills Bay.

The turning circle will allow all vessels to enter and egress Gills Harbour in forward motion for the first time and will be undertaken by Pentland Ferries Ltd's Gills-based 'direct labour squad', under long-term foreman Donald 'Donnie' Shearer, of Upper Warse, Canisbay.

One of HiFlo-4's very first tasks will involve the deployment of electricity-generating turbines in the fast-flowing tidal streams of the Pentland Firth's Inner Sound, the narrow channel separating Stroma Island from the Caithness mainland's Canisbay shore.

Mojo Maritime Ltd has been chosen by MeyGen Ltd, the holders of the Crown Estate seabed lease there, to install the first six turbines on the 30+ metre deep Inner Sound seafloor, in a first-phase 'demonstration tidal array', starting from late next summer (2014) and continuing on into 2015.

This is the first of a planned 396 turbines to be emplaced for MeyGen Ltd on the Caithness flagstone bedrock of its Inner Sound concession for 2020/21. This is expected to become the World's first major sub-sea tidal stream power station, with a planned output of 400 MW, half as much again as Dounreay's now-closed Prototype Fast Reactor, which operated from 1972 to 1994.

The Cornish company late last year won the 2012 industry-award 'Oscar' for the HiFlo-4 vessel's concept at the Tidal Today International tidal energy Summit in London chosen by an independent panel of 'peer review' industry experts.

Her updated details will be eagerly studied by delegates at this week's All-Energy Exhibition & Conference in Aberdeen, where Mojo Maritime is exhibiting and where a conference address is programmed for Captain Parkinson. Many regard Hiflo-4 as bringing innovative 'game-changing' technology to the nascent tidal-stream electricity industry.

There are three other Crown Estate lease-sites in the narrowest Eastern part of the Pentland Firth where the tidal streams flow most swiftly, including Scottish Power Renewables Ness of Duncansby site, off John O'Groats. The two others lie off the southern coast of Orkney. Those operating consortia have all expressed an interest in utilising HiFlo-4's unique, ground-breaking technology for installing their turbines, as has a French consortia planning a sub-sea tidal power station between Alderney in the Channel Islands and France's Cherbourg Peninsula.

MeyGen Ltd's site lies between 1 and 1.5 miles off the entrance to Gills Harbour, the Ness of Duncansby is 4 miles distant, while the Orkney sites, off Cantick Head and South Ronaldsay's Brough Ness, are both
only 8 miles from Scotland's most Northerly mainland port. All can be reached by sea without the need to cross (i.e. transit) any of the Firth's 'tidal races' such as the Merry Men of Mey or the Bore of Duncansby, where breaking white-water occurs daily on the appropriate part of the 12.5 hourly tidal cycle.

Hi-Flo-4 will be c. 12 metres shorter than Pentalina, the Pentland Ferries Ltd modern catamaran RO:RO passenger and vehicles ship, which has carried the bulk of the Caithness to Orkney trade in the three-week absence of the Hamnavoe from the Scrabster to Stromness route, while dockyard workers at Babcock International's yard at Rosyth, near Dunfermline, Fife, worked round the clock to replace her irreparably-damaged starboard engine crankshaft. Pentalina has added an extra sailing to its thrice-daily year-round schedule on occasions to meet with the extra demand, with the 12-passenger freighter Heilliar 'deputising' for the absent Hamnavoe.

The Mojo Maritime vessel's key features are a 250-tonne capacity A-frame crane at the stern of the ship and an innovative Dynamic-Positioning (DP) system. using four Voith-Schneider vertical-axis variable-pitch propellers (one at each of the catamaran's four 'corners' which the company claims will hold her steady in currents of up to 9/10 knots. These will also drive and steer the ship, whose catamaran configuration ensures a steady work-deck.

HiFlo-4 will use an innovative drilling system devised jointly between German specialists Bauer AG and Mojo Maritime for boring the foundations for cylindrical circular steel 'mono-piles', into which the outer steel 'jacket' section of the generating turbines will be slotted.

The drill-bit will be controlled by engineers from HiFlo-4's bridge by a flexible umbilical 'bundle' which will allow a 2 metre diameter borehole to be drilled 10 metres down into the seabed; a further c. 8 metres will protrude above the seafllor for the slotting operation, as above. This system had been proven in successful trials at the European Marine Energy Centre (EMEC) off Eday, Orkney, where both seabed and tidal conditions are broadly similar to those in the Inner Sound.

Hi-Flo 4 has been described as 'game-changing' as she will perform tasks which up to now have been conducted on prototype tidal turbines using much bigger (c. 150 metres) deep-sea offshore construction vessels, designed for working on sub-sea oil and gas fields, such as those in the Atlantic Frontier out to the West of Shetland or in deep seabed areas in the Gulf of Mexico. Such vessels can have a day-rate charter price of approaching £100,000 per day and require deep-water ports at distance from the tidal stream fields.

Mojo Maritime's catamaran is designed to work with two crews 'around the clock' once tidal-turbine installation get under way in earnest from c. 2016 onwards in the Firth. Adaptations to her drilling system allow the mono-piles to be carefully emplaced vertically and grouted securely into position on the seabed.

Said Bill Mowat, chairman of community-owned Gills Harbour Ltd, which leases part of its landholding there to Pentland Ferries: "Obviously this is good news for us, the Caithness community, and for the harnessing of the Pentland Firth's tidal streams using recently-developed 'horizontal hydro-electricity' technology, and let's hope that it continues well into the future".

Amongst the many delegates attending the Aberdeen show is Richard Hunt of West Mey-based EnergyHunt Ltd, the leading Caithness firm in the 'renewables' field. He is a director, and former vice-chairman, of Gills Harbour Ltd.