Proposals can be a game changer for workboats
Stone concept from Norway is attractive for Inner Basin proposed ‘new’ east wall — saving money over mass-concrete construction.
Since at least medieval times, Gills Haven — at the landward apex of Gills Bay where the harbour now lies — has been considered to be free of North Sea-origin easterly swells that are driven into the Pentland Firth during the west-flowing twice-daily ebb-tide phases, each of around 6.5 hours.
This is largely because of the nature of the coastal topography to the east of Gills Harbour, i.e. Ness of Huna, Ness of Quoys, etc.
And it is near-certainly the reason naval advisors to King James IV of Scots arranged for the “allocation” of the lands of Warse as well as Duncansby (four miles to the east) to the (immigrant from the Netherlands) de Groot or Groat merchant family to inaugurate “royal” ferry links to the then, recently acquired, Orkney in 1496. This was the beginning of the merchant Groat family’s short sea route Pentland Firth ferry trade, that lasted for 250 years.
As well as dockets from the Royal Estates on the islands, the Groat family ferried pilgrims across the firth. They had tramped on foot from all parts of Scotland to the Pentland Firth shores, before taking a ferry from Gills Bay to Scapa Bay. It lies just two miles from the tomb of St Magnus the Martyr in Kirkwall’s magnificent medieval cathedral — “Mansie’s Kirk” to the Caithnessians, using the pet form of the saint’s name.
Warse Haven also lies at the landward head of Gills Bay, 200 metres east of the present harbour, and had small boat usage (cod-fishing by hand-line) until Gills Bay pier was constructed in 1905. The Duncansby “ferry haven” — at the site of the present John O’Groats harbour — is just one mile from the open North Sea. It is noticeably vulnerable to heavy, potentially-damaging, swells from that direction.
Winds from an easterly quarter occur for one-third of the time in the Pentland Firth area, compared to the two-thirds of the year when winds, from gentle breezes to storm-force hurricanes, are blowing in from the prevailing westerly (i.e. from the open Atlantic) direction. There are occasional Pentland Firth “calms”, but those have been discounted for clarity here.
North Sea origin swells produce short, sharp, vicious waves that can frequently close to any navigation exposed Scottish east coast ports, from Wick down to Eyemouth, especially in winter.
But at Gills, the ferry company’s recently-deepened — rock-dredged down to c. minus 4 metres — safer-operations “ship-turning circle” with a width of 100 metres, has brought smaller, but unbroken, sea-swells right in to the Gills Inner Basin’s present entrance channel. Previously the rollers broke on nearby “drying rocks” lying seaward of the channel; those inter-tidal shelving shallows have now been dredged away.
Thus, to provide low — or non — surface turbulence inside a deepened basin, some artificial protection must be provided in the form of a mini-breakwater from the seaward end of its east side or perhaps even its main entrance channel should be re-positioned there.
The first, and earliest harbour improvement proposals — drafted for the visits of Transport Scotland officials and the (then) Scottish Energy Minister Rt. Hon. Fergus Ewing in 01.2016 — is (A) by Clifford Shepherd, the civil engineer from Quoys of Canisbay Farm, GHL’s vice-chairman and also “landlord” to Atlantis RL’s shore facilities.
His farm includes the Ness of Quoys cable landfall site where the associated power conversion building(s) were recently erected. The PCB is filled with multi-million pounds-worth of state-of-the-art electrical relay etc. equipment, supplied to Atlantis RL by huge Swiss/Swedish conglomerate ABB.
Mr Shepherd’s sketch shows an easterly entrance, but this needs an internal division. It has a new east pier aimed at handling loads up to 20 tonnes.
This was to have been the opening gambit in any Gills Harbour Ltd negotiations with public-sector Transport Scotland. It would have undoubtedly provided Inner Basin shelter.
But, with a partial length load-bearing new East Pier as well as the freight-loading jetty as an internal “divide”’ wall, the cost would have been considerable.
The second (B) is by GHL’s emeritus director Billy Magee.
It was inspired by Atlantis RL’s Tim Cornelius’s recent call for tidal energy costs to be minimised, without compromising safety.
It aims to provide safe work-boat usage and lowest-possible price.
Achieving actual facilities based on this sketch — or a near variation on it — is likely to be GHL’s main contribution to that end. (*Note that the seaward-extended South Quay is not drawn in).
Mr Magee has a lifetime’s experience as an operator of wooden small-boats with low-power engines from Gills Pier/Harbour.
Known as yoles (but resembling dories), these little boats have origins dating back to ancient Viking-era times. Mr Magee has hand-built several himself to help keep these traditional Pentland Firth skills alive on this coast.
He has an excellent knowledge of Inner Sound tidal streams and sea-swells in varying weather conditions, including the waves impacting the landward head of Gills Bay, which local folk dub “land-sea”. This is backed up by (dated) photographs that the semi-retired former Gills Harbour active office-bearer has taken of the facility and its environs over the past 30 years.
This can enable recorded metrological conditions in the Pentland Firth area to be checked against his fine Gills photographic archive library.
Most importantly, this basic design cuts construction costs and related outgoings to the absolute minimum, whilst producing an “always-available” safe operational capability.
Any other further desirable Gills Harbour improvements can be installed/constructed later, dependant on the port’s income/cash-flow.
His draft sketch is recent (12.2016) and is aimed at maximising the available area of Gills Harbour’s 60-metre wide Inner Basin, without creating internal sub-divisions that are likely to be (relatively) expensive to provide.
To slash end price of tidal electricity (LCOE), the Gills Harbour inner basins internal dividers have been omitted from the final proposal
At present, although the recycled ferry triple-breakwater is very effective at blocking westerly (i.e. Atlantic origin) swells, the “tail-ends” of those much-reduced waves can proceed along the inside edge of the 116-metre long recycled breakwater. From there, they spill into the Inner Basin along the side of Gills Pier, running up onto the hard-slipway and, in extreme conditions, splashing over the South Quay.
This was the case until the 70 metre “offset” breakwater/berth extension was emplaced in position in 2016. It is understood that Pentalina’s deck-officers have noted considerably less vertical sea-movement at her link-span berth in the 2016/17 winter, since its installation. This also means less disturbance in the existing Gills Inner Basin, as was observed in late 2016. The ferry link-span (“bridge” from land to ship’s car-deck) lies adjacent to, but just beyond the seaward end of Gills Pier, to its immediate North West).
However, sea-surface turbulence is unavoidable for so long as the Inner Basin’s entry channel runs almost alongside the stone-built Gills Pier, just to the east of the pier-width light-loading steps at its seaward extremity.
This would be prevented in B) that shows a short (c. 25/30 metres) new South East-trending mini-breakwater for the Inner Basin commencing just beyond the seaward end of the stone-built Gills Pier. It would also retain sea-access to the pier-width “steps”, continuing in used for livestock handling for low, ”green” Stroma island, now run as a Simpson family sheep-farm.
B) also shows a longer new mini-pier/breakwater heading some 50 metres in the NW direction from the eastern side of the basin. This would effectively quell any North Sea origin swells, as related above.
As is seen at low-water “streams” (i.e. spring tides), the strata of bedrock here lies near-horizontally. This would permit land-side access by ready-mix concrete trucks, or dumper-trucks, to pour into steel shutters pre-placed there.
This would avoid problems in transporting “10-tonne” pre-cast concrete blocks, such have proven so effective at protecting the west side of the landward end of the Pentland Ferries breakwater and are still being extended seawards.
The Inner Basin would be dredged down to minus 2.5 metres LAT (Lowest Astronomical Tides). There would be a “new” vertical-face South Quay, as the safe berth(s) for multi-cat workboats.
This new upright wall, a few metres to the seaward of the present Quay, would probably be constructed using “tied-together” interlocking pre-cast concrete blocks, as recommended by civil engineer Robert Cross, who had 30 years’ experience of constructing ferry-harbour works in Orkney, at all of the archipelago’s major offshore islands.
Perhaps the outstanding feature of the basic (B) proposed lay-out is its capability for further internal additions, as GHL’s future revenues permitted.
Creel-boats (used by local crews fishing passively for lobsters, velvet and brown crabs in ad near the Inner Sound) are valued GHL customers.
These small boats (typically 8-10 metres) could be safely kept afloat in the Basin year-round, for the first time ever.
They could ‘lie off’’ the main Pier, tie up alongside a multi-cat or two at the (new) South Quay or perhaps later be catered for by a floating marina-style structure in the Basin.
There is a great deal of flexibility built in to this proposed basic Inner Basin layout, but one also easily allowing for future sustainable usage by tourism-related sea-mammal watching excursion boats or leisure-dive vessels.
The larger boulders in the existing “tip-rap” mini-breakwater of the present Inner Basin would be retained for re-use.
These would then be re-built in a “new” Inner Basin stone east (boundary) wall, in a similar manner to what has been done close to its present south-east corner.
This was undertaken in 2014 by the civil-engineering contractor working for Highland Council, who was restoring storm damage, considered potentially likely to affect the stability of the final bend of the Gills Harbour access road.
The dry-stone, attractive-looking wall at the Inner Basin’s SE corner was adapted by contractor Billy Sinclair (MD of A & W Sinclair Ltd., civil engineers and quarry-masters, of Caithness) from examples that he observed while attending a family wedding in Norway, where this technique is often regarded as preferable to using mass-concrete.
It can be cheaper, if suitable-size and shape boulders/large stones are available locally, as is the case here. It also arguably looks better. This was the first occasion that A & W Sinclair Ltd. had used this method and thus the small century-old family firm has expertise in a technique that could be of much further use at Gills Harbour.