Tag Archives: flow

One for the Phizzers

Quite a few visitors to this site come to read about the Broadstone. Here is a piece about the pontoon bridge used at the Broadstone between (AFAIK) 1847 and 1877. It was designed by Robert Mallet and it is interesting to see how an inventive engineer solved the peculiar problems of the Broadstone site.

Newcomen Bridge

Mick Farrell of the HBA has pointed out that, on the Historic 6″ Ordnance Survey map (~1840), the first lock on the Royal Canal is downstream of Newcomen Bridge whereas on the Historic 25″ (~1900) the lock is upstream of the bridge.

Industrial Heritage Ireland has created a page giving the history of the railway crossing at Newcomen Bridge. However, it would be nice to have some documentary evidence about the resiting of the lock — and about the headroom under the bridge before the lock was moved.

Errina Bridge

I remarked in November 2012 that Waterways Ireland had parked a canteen trailer and some pontoons at Errina Bridge, the uppermost bridge on the Plassey–Errina Canal, which is part of the old Limerick Navigation.

WI pontoons

WI pontoons

WI canteen

WI canteen

I wondered what was to be done; I noted that a stone at the top of one of the stop-plank grooves under the bridge had been removed (the stone on the far side was removed some time ago).

So I asked Waterways Ireland what was happening. They said:

The works in Clonlara are Flood relief works to protect Errina Lock from catastrophic failure. After the flooding in 2009, during which the dam in Errina Lock was overtopped by approximately 0.5 metres, it was decided to protect it from this happening again.

It has happened before too: in February 1809 the lock was destroyed by floods when heavy snows melted.

Errina Lock (looking upstream)

Errina Lock (looking upstream)

I asked WI about the nature of the works. They said:

Stop logs are to be put into the grooves under the bridge forming a dam with the same size opening as that in the concrete dam in Errina Lock. As for the stone which is removed to facilitate the installation of the timbers, this will be replaced once the timbers are in place.

That is good to know.

Errina Bridge stop-plank grooves (towing-path side, with uppermost stone removed)

Errina Bridge stop-plank grooves (towing-path side, with uppermost stone removed)

Errina Bridge stop-plank grooves (off side)

Errina Bridge stop-plank grooves (off side)

An authority on waterways has suggested that the curious shape of the grooves was designed to allow planks to be inserted from boats rather than from land.

 

Disband Clare County Council

In order to save some money, it might be a good idea to disband Clare County Council. Then we wouldn’t have county councillors proposing idiotic projects (joined in this instance by some TDs) requiring vast capital expenditure (which we can’t afford) to produce zero jobs.

More about Ardnacrusha here.

Shannon private boats

Recorded lock and bridge passages for the first ten months of the year.

Shannon private boats 2003–2012

Shannon private boats 2003–2012

In almost every year, the last two months, November and December, saw far more private boats than hired boats moving.

Water levels

Meelick Weir today

Meelick Weir today

Almost level.

Royal water

The Royal Canal water supply applications have been approved by An Bord Pleanala. There were two separate applications [see here and here] but they were in effect treated as one. There are five PDFs available on each page and I haven’t read all of them yet. However, on a first glance, I note that:

2. The proposed development shall be operated as follows:

(a) Rates of abstraction from Lough Ennell to the Royal Canal shall be as specified  in the public notices and, in particular, shall not exceed 43,636 cubic metres of water in any 24 hour continuous period and subject to a total maximum abstraction of 6,586,363 cubic metres per annum.

(b) Abstraction from Lough Ennell to supply the Royal Canal shall cease when the  lake level reaches 79.325 mOD Malin Datum, being the crest level of Clonsingle weir, measured at Clonsingle weir by continuous monitoring.

(c) The fish pass at Clonsingle weir shall incorporate a minimum flow of 0.29m3/second.

(d) A minimum flow of 682 m3/day (0.5MGD), taken directly from Lough Owel, and excluding water from the fish farm, shall be retained in the original canal feeder.

Reason: In the interest of protecting the integrity of the Lough Ennell Special Area of Conservation and the ecological interest of the River Brosna and the canal feeder, and in the interest of protecting material assets at Lough Ennell and the River Brosna.

If I remember correctly, the amount of water available from Lough Ennell will not always provide enough (eg in a dry season) to keep the canal full. Still, this is a significant advance for Waterways Ireland and for Royal Canal enthusiasts.

Preparing for winter

WI at work in Killaloe Novemebr 2012.

Old crane being painted

 

The Marindus weedspraying pontoon. This Marindus may be Marindus Engineering Ltd of Kilmore Quay, Co Wexford

For the record

The Limerick Leader article about a proposed Limerick river bus has some statements that do not accord with my understanding.

The venture will see the river bus depart Guinness Pier – across from Athlunkard Boat Club at O’Dwyer Bridge – every two hours, bound for the power station […].

As far as I know, the pier in question was the Ranks jetty and was not used by Messrs Guinness. The Eclipse Flower, and other vessels owned by Ranks and their predecessors, sailed up the Shannon from there rather than attempt the stretch from Baal’s Bridge to Custom House Quay.

The boat will follow the route taken by barges of old – both passenger and commercial – some of which historically transported Guinness to the city up until the mid-1960s.

“It is a tried and tested route,” said Mr Flynn, stressing the viability and safety of the route, which passes Long Pavement – the edges of which have been repaired and grassed over – and finishes at the hydro-electric plant.

“Every passenger and commercial barge that came to Limerick for 50 years used that stretch of water. It is very safe. It was navigated by all the barges,” he said.

The route to Limerick through Ardnacrusha came into use only after the construction of the power station in the 1920s and was used for a little over thirty years. To the best of my knowledge, there were no passenger services in those years: passenger carrying stopped in the first half of the nineteenth century, when traffic was still using the old Limerick Navigation. There have been some trip-boats in recent years, but they did not (and do not) use “barges of old”. Some old barges, now converted and with more powerful engines, have safely navigated that stretch, but they do it when conditions are right.

During the final phases of Ardnacrusha’s construction, both old and new navigations were closed; the Grand Canal Company (GCC), the main commercial carrying company, ran to Killaloe and had its cargoes carried onward by rail to Limerick. When the new route through Ardnacrusha was opened, the GCC thought it was so dangerous that it refused to use it for about a year. It resumed operations only when a boom was put across the river above Baal’s Bridge and posts were provided upstream of O’Dwyer Bridge to which barges could tie while waiting for suitable states of the tide.

I accept that the proposed river bus will not be going downstream as far as Baal’s Bridge, but it will still be navigating on a stretch of water where Waterways Ireland advises that boats should not navigate when more than one turbine is running at Ardnacrusha. The ESB can run up to four turbines, each of which is said to add a knot to the current, and it can switch them on immediately, with no warning to any boat using the river.

Other pages on this site make it clear that I share the promoters’ enthusiasm for Ardnacrusha and the canal and river thence to Limerick. I do not say that the difficulties of that stretch cannot be overcome, but I do not think that they should be dismissed.

 

That Limerick “river bus” …

… from the (presumably artificially created) photograph in the Limerick Leader seems to be the Cailín Turána, formerly part of the Aran Islands Fast Ferries fleet at Doolin and seen here out of the water at Cork Dockyard in 2004. The vessel has not been on the Dept of Transport’s List of Certified Passenger Ships since 2007 (and may have come off the list before that: I have not kept copies of the lists earlier than 2007). It could of course have been used in Ireland for purposes other than carrying fare-paying passengers, or outside Ireland for any purpose, after 2004.

And it may be that the vessel shown in the photo is not that which is to be used in Limerick.