KRY12_03 / GEO12_02 - Inishbofin, Inishturk & Killary Harbour

In July and August 2012, the RV Keary and RV Geo spent several weeks mapping the seabed around Inishbofin, Inishturk and Killary Harbour. The vessels were based in Inishbofin harbour for the duration of the survey.

Initially, two specific sites were mapped for BIM (Bord Iascaigh Mhara) who are investigating the potential of deep-water aquaculture sites in the area. In addition, a larger area around the islands was mapped to provide bathymetric data for oceanographic current modelling to be carried out by the Marine Institute, along with extending INFOMAR coverage into the area around the islands.

The survey data revealed very interesting underwater topography, containing extensive rocky outcrop, fault lines and sedimentary features.

Below are images of the survey coverage and the vessels at work. Note that the colour scales may vary between the survey coverage images - the red and blue ends of the spectrum represent shallower and deeper water, respectively.

Survey coverage by RV Keary and RV Geo around Inishbofin and Inishturk. The RV Geo carried out the shallower water mapping along the coastlines. Data in this image is still in the process of being finalised and contains some errors.

The "Stags" rocks off the NW coast of Inishbofin.

A view of Inishturk's rugged coastline from the RV Geo.

RV Keary.

A backscatter map of the seabed around Inishbofin and Inishturk, merged with a shaded relief map. Backscatter maps are produced from the strength of the sound waves returning to the multibeam sonar, having reflected off the seafloor - this provides information on seafloor hardness, which is then represented in greyscale here (darker shades represent harder seabed). The grey polygon in the centre and eastern part of the map represents the extent of seabed previously mapped by the RV Celtic Explorer.

Folded rock strata on Inishturk's coastline. The onshore geology on both islands is complex and ancient - the seabed mapping carried out during the survey should help to extend the understanding of it into the offshore environment.

RV Keary transiting from Inishbofin to Cleggan.

RV Keary tied up alongside Inishbofin's ferry, the Island Discovery, in Inishbofin harbour.

Structural geology of Inishturk, with seabed coverage by RV Keary and RV Geo around the island. Onshore, faults are shown in black and the synclinal axes of folded strata are shown in red. The fault marked with the red arrow appears to extend offshore in a south-easterly direction as a discontinuity in the seabed rock outcrop.

Along with successfully acquiring bathymetric data, the INFOMAR vessels completed inshore mapping around Inishbofin and Inishturk - the data will be freely available in several formats on the INFOMAR website in the future.

KRY12_02 Bunmahon

Between the 13th and 18th June 2012, the RV Keary carried out seabed mapping off the coast of Bunmahon, Co. Waterford. This survey was conducted in support of the INTERREG funded Atlanterra Project, which has designated the Bunmahon area as a Geo-park. Learn more about Atlanterra at http://www.gsi.ie/Programmes/Heritage+and+Planning/Heritage/Atlanterra.htm.

During the survey work the Keary was based in the port of Dunmore East, from which the vessel could transit to the survey area. Existing bathymetric data lay to the south, having been collected by the RV Celtic Voyager in 2007, and it was ensured that the RV Keary's coverage overlapped with that to provide quality control on the data.

Two uncharted shoals were mapped during the course of the survey, with this information then delivered to the UK Hydrographic Office (UKHO) in the form of H-notes. The UKHO will then issue a Notice to Mariners, alerting them to these hazards and will include the shoals in New Editions of charts.

Examples of the data collected are below:

Seabed data collected off Bunmahon shown as shaded relief

Backscatter image of the seabed off Bunmahon. The RV Keary uses a multibeam sonar to map the seabed - when the sound waves it produces reflect back off the seabed, the strength of the return provides information on the hardness of the seafloor material. This greyscale map was produced using that data. Note also that this image shows the data collected by the Celtic Voyager to the south.

Shoal discovered during survey operations - originally charted at 14m depth (LAT) but now found to be at 7.5m depth (LAT). The top half of the image shows it in plan view, while the lower half is a profile view. LAT = Lowest Astronomical Tide.

INIS-Hydro - 2012 Progress

The 2012 survey season began with the RV Keary and RV Geo vessels making a return to Dundalk Bay, to continue mapping as part of the INISHydro Project. Both vessels have been re-mobilised and kitted out with survey instrumentation after wintering in Dublin.

The Geo, a 7.5m RIB operated by the Geological Survey of Ireland, underwent some significant re-fitting - this took the form of an extension to the aft part of the cabin, allowing for a larger work area for the surveyor's station and an equipment rack for the dry end of the survey instrumentation. A generator was also fitted in the Geo's engine bay, which removed the previous reliance on batteries to power the survey gear. These additions have greatly increased the RV Geo's capabilities as a survey craft.


RV Keary arriving into Port Oriel at sunset. Both vessels operated from this harbour, which is situated south of Dundalk Bay

INIS-hydro is a 3 year INTERREG IVA Programme with the Maritime and Coastguard Agency (MCA) in the UK as lead partners. The project brings together 7 partners to conduct hydrographic surveys in Ireland, Northern Ireland and Scotland. The partners are the MCA, Geological Survey of Ireland (GSI), Marine Institute (MI), the Agri-Food and Biosciences Institute (AFBI), the Scotish Association of Marine Science (SAMS), the Northern Lighthouse Board (NLB) and the United Kingdom Hydrographic Office (UKHO).


Areas of seabed to be mapped during the INISHydro project

The surveys will be undertaken in Dundalk Bay, Carlingford Lough, Dundrum Bay, the Firth of Lorn and South West of Islay by several different vessels drawing on expertise from the various partners. The bathymetric data will deliver 3D baseline maps using multibeam echosounder technology which will be freely distributed. The project also plans to harmonise hydrographic survey specifications and synchronisation for future surveys.


INISHydro partner organisations

These surveys comply with the partners obligations under the Safety of Life at Sea conventions and will be augmented with auxiliary scientific data collected in conjunction with the bathymetric data. Details of the project can be found on the website at http://www.inis-hydro.eu/

The project is essential as the current nautical charts for these areas were produced largely in the 19th century and whilst they were an enormous achievement for the surveyors of their day, these charts are not as reliable as their terrestrial counterparts and warrant updating. The territories to be mapped in the INISHydro project encompass important navigation channels, areas of environmental interest and potential sites for marine renewable energy. INISHydro also involves a very significant level of cooperation, bringing together so many partner organisations.


RV Keary and RV Geo in Port Oriel. Note the cabin extension on the Geo, which was added prior to this survey season

INISHydro mapping in 2012 commenced in April, with the arrival of RV Keary and RV Geo in Port Oriel. The vessels worked in partnership, with the Keary focusing on the approaches to Dundalk Harbour and the Geo carrying out survey operations around Dunany Point and the southern, shallow portion of Dundalk Bay.


Strong winds resulted in a rough sea state at times

Due to the exposed nature of Dundalk Bay, operations were sometimes hampered by regular strong, easterly winds. However, in spite of this the vessels significantly extended the bathymetric coverage that was gained last year (bathymetry is the water depth). The Keary mapped out a large wedge-shaped area of seabed that includes an interesting channel-like feature - this feature was also noted in last year's INISHydro blog entry.


RV Keary 2012 bathymetric coverage (does not include RV Geo coverage)

The Geo extended last year's shallow water coverage into an area of shoals around the headland of Dunany Point at the southern extent of Dundalk Bay, along with merging with RV Keary coverage to the east.


RV Geo coverage to date, merging with Keary coverage in the east. Note that the colour scale is different from the previous image - similar colours between the images do not represent the same depth


Mini ROV (Remotely-Operated Vehicle), a valuable tool for inspecting the Keary's propellors

Kilmore Quay, Wexford & Rosslare Surveys

After completing the first survey leg of the 2011 season in Waterford Harbour, the Geological Survey of Ireland's (GSI) 7m RIB (Rigid Inflatable Boat), RV Geo, was taken out of the water in late June and transported by land to Wexford for the second leg - surveys of Wexford Harbour, Kilmore Quay and Rosslare. The latter was predominantly carried out by the GSI's 15m aluminium catamaran, the RV Keary, while the first two areas were mapped solely by the Geo due to their very shallow nature.

Wexford proved to be a highly challenging area to survey, with numerous shallow sand banks forcing the Geo to operate in waters as shoal as 2m. With its fragile transducer hanging 0.6m below the waterline, this required great skill on the part of the skipper to safely manoeuvre the vessel through the shallows. To further complicate matters, the sand banks of Wexford harbour are highly mobile, and so their distribution no longer matched the existing nautical charts - hence the great need for an updated survey of the area.
Along with a requirement for very careful navigation, the survey crew also had to keep a careful watch on the tidal conditions. Due to its shallow nature, safe navigation between the shoals of Wexford harbour is extremely restricted by the tide - in many areas the Geo could only operate at high tide, with some of those areas drying out at lower water levels.



RV Geo on survey operations



RV Keary navigating off the coast

Another feature to note in Wexford harbour was the presence of a large seal colony. Great care was taken not to disturb the creatures during survey operations and so the Geo's surveyor also doubled-up as a marine mammal observer (MMO). In addition to reporting on the survey, the surveyor created an MMO report detailing sightings of the seals - a useful dataset in itself for marine biologists.



Survey area mapped by the RV Geo through Waterford Harbour. The blue end of the colour scale represents deeper water, with the shallow seabed represented as green, through yellow to red.




A large number of seals were observed on the edge of the sandbank in Wexford harbour


In addition to mapping the seabed with sonar, the crew of the RV Geo also collected many sound velocity profile (SVP) data.
The SVP data is necessary because the sonar systems measure the travel time of sound waves through the water. As water temperature and salinity differ from within and between survey areas, so too does the speed of sound. Therefore these effects must be corrected for in order to accurately map the seabed. The SVP data was acquired by lowering a probe down into the water column, measuring the temperature and salinity of the water and therefore providing the survey team with a record of the sound velocity in a given location. By conducting regular sound velocity casts in Wexford harbour, the team ensured that the final dataset would require minimal processing to correct for errors created by the changes in the water column. The advantage of acquiring this data is that the information gathered during the survey constitutes a unique dataset which can have additional use in the study of the local oceanography of the area.


Following the survey of Wexford Harbour, the RV Geo was transited by sea to Rosslare harbour. The RV Keary had commenced survey operations in Rosslare at this point, and both vessels conducted survey operations in the area. The RV Keary conducted the bulk of the survey work, with the Geo briefly carrying out bathymetric mapping.



Survey coverage in Rosslare harbour


Following survey operations in Rosslare, the RV Geo was taken out of the water and transported by land to Kilmore Quay, while the RV Keary remained in Rosslare to continue operations. A similar survey strategy was employed at Kilmore Quay, involving further mapping of the seabed using sonar and SVP data acquisition. A feature of interest off the coast there is St. Patrick's bridge, a ridge of raised seabed that juts southwards. Along with shallow areas near the harbour, this feature could only be crossed by RV Geo at high tide, and so like Wexford this survey also included tidally-restricted areas.



Survey coverage by RV Geo at Kilmore Quay

INIS-Hydro Project

INIS-hydro is a 3 year INTERREG IVA Programme with the Maritime and Coastguard Agency (MCA) in the UK as lead partners. The project brings together 7 partners to conduct hydrographic surveys in Ireland, Northern Ireland and Scotland. The partners are the MCA, Geological Survey of Ireland (GSI), Marine Institute (MI), the Agri-Food and Biosciences Institute (AFBI), the Scotish Association of Marine Science (SAMS), the Northern Lighthouse Board (NLB) and the United Kingdom Hydrographic Office (UKHO).

The surveys will be undertaken in Dundalk Bay, Carlingford Lough, Dundrum Bay, the Firth of Lorn and South West of Islay by several different vessels drawing on expertise from the various partners. The bathymetric data will deliver 3D baseline maps using multibeam echosounder technology which will be freely distributed. The project also plans to harmonise hydrographic survey specifications and synchronisation for future surveys.



Areas of seabed to be mapped during the INISHydro project


These surveys comply with the partners obligations under the Safety of Life at Sea conventions and will be augmented with auxiliary scientific data collected in conjunction with the bathymetric data. Details of the project can be found on the website at http://www.inis-hydro.eu/


The project is essential as the current nautical charts for these areas were produced largely in the 19th century and whilst they were an enormous achievement for the surveyors of their day, these charts are not as reliable as their terrestrial counterparts and warrant updating. The territories to be mapped in the INISHydro project encompass important navigation channels, areas of environmental interest and potential sites for marine renewable energy - it also involves a very significant level of cooperation, bringing together so many partner organisations.

INISHydro partner organisations

In September 2011, three vessels were mobilised to Dundalk Bay to begin mapping the Irish territory – the RVs Keary and Geo were supplied by the GSI and RV Celtic Voyager was provided by the MI.

RV Celtic Voyager



RV Keary



RV Geo

The Voyager carried out bathymetric mapping up to the 10m depth contour, while the Keary and the Geo were assigned to shallow-water mapping up to the 5m and 0m contours, respectively.

While the Voyager operated out of Howth, Co. Dublin, on a 24-hour basis the Keary and the Geo were based locally, carrying out surveys in daylight hours and mooring at Port Oriel overnight.
This was also the location of a tide gauge for the duration of the survey, along with a GPS base station which was deployed at a private residence nearby. The tide gauge provided a record of the tidal changes in the area throughout the survey, which is necessary as the bathymetric data must be corrected for the resulting rise and fall of the survey vessels during their operations. The GPS base station was used to improve the positioning accuracy of the survey data during processing.

Total survey coverage for Dundalk Bay during the 2011 survey.

In addition to bathymetric data, the Keary and the Voyager recorded a sub-bottom profile along each survey line using shallow seismics. East of Dundalk, an interesting channel-like feature was observed in the data, which requires further geological analysis.

Sub-bottom profile showing channel-like feature east of Dundalk Bay




Channel-like feature visible in the Keary's bathymetric data as dark blue strip

Maritime Archaeology aboard RV Keary

Since INFOMAR began in 2006, the survey team have regularly supplied data to the Underwater Archaeology Unit (UAU, part of the Department of Arts, Heritage & Gaeltacht) on a variety of shipwrecks that have been surveyed around the Irish coast. The process involves the sharing of detailed sonar data (multibeam and sidescan), which the UAU analyse in order to help ascertain whether a given wreck is known or unknown, whether or not it needs to be protected, and to improve the accuracy of the national shipwrecks database. INFOMAR and the UAU also publish wreck information sheets together, which are available to download at www.infomar.ie – these provide information on the locations of particular wrecks, their water depths, history and any diving information if available.

At the start of August 2011, this partnership was developed further when RV Keary and RV Geo gave support to the UAU in an archaeological excavation of a potential Spanish Armada wreck near Burtonport, Co. Donegal.

The Rutland Island Wreck, named after a nearby island, had been discovered two years previously by local divers, and had already been investigated by the UAU. However, it had not yet been properly excavated, and so the Keary was provided by the Geological Survey of Ireland as a dive platform to facilitate the team of maritime archaeologists in this endeavour.

RV Keary and UAU vessel moored together above the wreck site




Marine archaeologist wearing commercial diving gear, emerging at the stern of RV Keary

The vessel served very well as a base of operations for the team, providing ample space for their specialised diving equipment – tanks and compressors that provided surface-supplied air, and a communications setup that allowed dialogue between the surface team and the divers below. The vessel’s hydraulic A-frame also played a role in recovering some of the UAU’s equipment from the seabed at the end of the project, and several areas were provided on deck for the analysis of recovered artefacts. One of the Keary's instruments, called a USBL (Ultra-Short Base Line), was also used to great effect in pin-pointing locations on the seabed that were of interest to the archaeologists. This is an acoustic transducer, located on a hydraulic drop-pod between the catamaran's hulls, that can communicate with a set of beacons. The divers assembled a metal grid over the wreck in order to assist with mapping of its various timbers and artefacts, and by placing these beacons on its four corners, the Keary's USBL could be used to give accurate coordinates for the grid's location - and therefore accurate positioning for all discovered artefacts. One beacon was also carried by a diver carrying out metal-detection on the seabed around the wreck, which meant the Keary's survey crew could provide him with coordinates for all objects that were discovered this way.



USBL display showing RV Keary at centre and recorded positions of beacons


The Keary also accommodated a variety of film and radio crews, who documented the excavation for privately-funded documentaries and public service broadcasting. All in all, the vessel played host to a huge variety of scientists, archaeologists and journalists over the three week period.

The INFOMAR, UAU and local dive teams aboard RV Keary

In order to establish a semi-permanent base at the site, the Keary was placed over the wreck and anchored at three points to hold her in position, with the Geo remaining mobile in order to ferry survey crew and archaeologists to and from the base of operations, along with carrying out her own bathymetric survey operations (mapping of water depths).

RV Geo carrying out bathymetric survey

The UAU provided their own RIB (Rigid Inflatable Boat), which tied up next to the Keary each day and excavated the wreck through use of a suction-dredger. The material removed from the site was fed to a sieve aboard the RIB, where a team of archaeologists sifted through the sand and mud to recover any small objects of interest that were removed by the dredger. All recovered objects were then moved to the Keary for analysis and storage.

Archaeologist on surface-supplied air, operating suction dredger (Photo courtesy of the Underwater Archaeology Unit)


Archaeologists aboard the UAU RIB, sieving through material suction-dredged from the wreck below.



Stern of the Rutlant Island Wreck. The metal grid was assembled on the seafloor by divers to assist with mapping of the wreck's timbers and artefacts (Photo courtesy of the Underwater Archaeology Unit)



Diver recording rope and barrel hoops exposed during the excavation





Artefacts recovered from the wreck, clockwise from top: bowl, shot, stone object and walnut shell (Photo courtesy of the Underwater Archaeology Unit)

Independently, RV Geo carried out sidescan sonar surveys of the wreck, along with expanding INFOMAR coverage of the surrounding area’s bathymetry (water depths) – the areas mapped by the Geo included several approach channels that are vital for navigation to and from the island of Arranmore, along with a sector near Lahan Island that had only been partially mapped during the days of the British Admiralty surveys.

The Geo's presence in the area allowed the team to progress INFOMAR seabed mapping while the Keary dedicated itself to the archaeological work, demonstrating once again the flexibility and efficiency that are gained by having both vessels operating together on site. The Geo's interferometer mapping system, which works like a Sidescan sonar, produced valuable imagery of the Rutland Island wreck that will be useful for further archaeological studies.

Sidescan Sonar image of the Rutland Island Wreck. The stern of the vessel is to the right (East). Note the pale shadow cast southwards by the metal grid (colours on Sidescan imagery are inverted here, with pale colours representing sonar shadow)



Total bathymetry mapped by RV Geo during the excavation



Area mapped by Geo near Lahan Island - this area was not completely mapped during the original surveys by the British Admiralty



Bathymetry mapped by RV Geo east and south of Rutland Island, including the wreck site



Shipping channel between Arranmore and Burtonport mapped by RV Geo

INFOMAR mapping of the Shannon estuary

INFOMAR mapping of the river Shannon commenced onboard the Marine Institute’s research vessel Celtic Voyager on July 19th. Over the course of the two-week survey leg, the estuary mouth was mapped up to the 10m contour, with physical sampling taking place at key locations in order to determine the seabed type (e.g. rock, sand, shell hash etc). The new seabed coverage was merged with existing datasets offshore and upriver. In addition to the geological mapping, a detailed survey was carried out over the wreck of the S.S. Premier – a British cargo steamer that was lost in 1898. This 54m long wreck lies upriver from the survey area, in a general water depth of 21m.

An overview of the survey area at the mouth of the Shannon estuary showing the newly acquired bathymetric data. The solid-colour areas indicate the extent of previous survey work.

The survey area is particularly important for a number of reasons – not only does the area incorporate a busy shipping channel, it is a Special Area of Conservation (SAC) for resident bottlenose dolphins, and from a geological perspective it overlies an important subterranean structure called the Iapetus Suture Zone – a large seam running through Ireland’s ancient bedrock that marks the closing of an ocean pre-dating the Atlantic by many millions of years.

The survey comprised bathymetric mapping of the seafloor from Kerry Head to Loop Head, with the inner extent lying along the 10m contour. As the area is an SAC for resident dolphins, the acoustic surveying took place during daylight hours only, with seabed sampling operations taking place at night. The sampling was carried out with a mechanical instrument called a “Shipek Grab” – this is a spring-loaded device that, upon being lowered to the seafloor, snaps closed and scoops up a bucket of material. Along with a variety of sediment types, the grab also returned a host of interesting biological specimens – squat lobsters, brittle stars, shrimp, crabs and solitary corals – all of which were logged before being returned safely to the sea.

In addition to the seabed mapping and sampling work, two survey lines were run at night outside the SAC, using a towed “Sparker” system to record a sub-bottom profile of the seabed sediments and bedrock. This device uses an electrical arc to create an acoustic pulse that penetrates the seabed. Where the bedrock is buried beneath soft sediments, this pulse can return a detailed image of the sediment layers and provide information on their thickness.
A variety of interesting seabed features were mapped in detail, and are detailed in the following images. Note that the colour scale represents depth, from deeper (blue) to shallower (red):

Outcrop of folded bedrock off Inishaboy Point, Co Kerry.

Shaded relief bathymetry indicates a channel feature visible in rocky seabed lying north of Kerry Head.
Distinctive layers of limestone off Horse Island, Co Clare.
Folded and faulted bedrock off Loop Head. A 3D multibeam image of the S.S. Premier wreck showing the hull of the vessel lying in a general water depth of 21m.

Multibeam echosounder image of the S.S. Premier in plan view.