- Digital Charts of Lough Corrib


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Sidescan Images

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This appears to be wreckage on the north shore – it is in a small bay, and the imagery was obtained by motoring very slowly around the periphery while scanning at a reduced range of 100ft either side of the survey craft using 455 khz . It is in less than 20 foot of water

In the hen castle image to the right, you can clearly see the jetty (near top left) and the large dangerous rock marked by marker 160 on the chart in the bottom left. The hundreds of salmon are lying in 8ft of water above a muddy bottom, just south of the rocky shore of the peninsular that leads out towards Hen castle

In this image, a wreck which is 32ft long approx can be seen and is in the vicinity of Oughterard. It is in less than 30ft of water

High voltage power cables running under the river near maam. However, these seem to have been washed out of the river bottom over the years, and now sit in mid-water at a depth of 6ft in 12 ft of water. Be careful when trolling!

These images show the some of the large number of Salmon waiting to ascend the Galway rivers from Corrib during September. They are very selective in where they choose to wait, some areas being completely devoid, others seeming to be a heaving mass of fish. These sidescan images are in low res (455khz) – the high res imagery (800khz) enables us to easily see individual fish, but lacks the range of lower frequencies. The standard sonar image shows classic “fish arches” which are produced as the cone of the low frequency regular sonar (83khz) encounters a target at the far edge of the sonar cone, then moves closer as the boat moves forward, and subsequently passes out of the cone at more or less the same range as it entered the cone

Fogarties Rk. Just north of Hen Castle (Castlekirk) in the Northern end of the lake. It is usually only about a foot under water, and as can be seen, is massive. It is probably a glacial erratic. There are a string of boulders lying ESE/WNW across the lake, with this rock being the largest. It sits on a bed of morain material which most likely indicates the direction of travel of the glacier. In the bottom of the picture you can see the shore of castlekirk, and the concrete jetty onto the island – this gives an idea of the scale of Fogarties Rk. This rock should certainly be considered for a permanent marker.

In the northern part of the Corrib, about 10% (or possibly less) of the bottom structure is rock - the rest is actually featureless mud

This shows the kind of amazing resolution that is possible with high frequency sonar. This is the water supply pipe into the corner of the pier at Lisloughrey supplying the pumping station

Interesting shot - these are BIG fish. This was in 60ft of water, but the shoal was off to port somewhere. You can see the sonar shadows of the individual fish on the bottom. We know the shadow is approx 45ft off to port (the unit works this out), and the apparent distance of the fish from their shadow is approx 50% of the distance of the transducer to the shadow aquick dooodle and they must be 30ft down and 23ft off to port. And BIG!

This appears to be the wreck of a barge near White Strand island. This is close to the route from the old mines in the upper lake to Oughterard / Galway so it’s very possible. The shallows around here are treacherous in a submerged Karst landscape

A 112ft deep hole completely missed by the admiralty survey, and full of fish. Notice the 2 vertical stacks of small fish, probably Roach or Perch on the high res sonar image. The small dots close by around them are more fish. On the traditional sonar image you can see both shoals again, and a large predator fish, either a trout or maybe a pike, near the top of the peak on the right hand side – at a depth of about 20ft. There was quite a lot of interference using this frequency

This is what looks like a bit of wreckage in the middle of the Needles Shallows (West of Cleenillaun). Its about 15ft long, rounded at one end and square at the other (Top right of sidescan image)

A lump discovered leaving Ashford, NE of marker 127

Tight but deep (15ft) channel between the shoreline and North of Conors Island. The spit extends out quite a bit North of the island which the sidescan clearly picked up

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