Tag Archives: clearance

The Newry bypass

I hesitate to criticise the Newry & Portadown Branch of the Inland Waterways Association of Ireland, admirable folk who conduct regular work parties improving the Newry Canal. So perhaps I should say that I disagree with them instead — at least on the proposal for a Southern Relief Road, aka bypass, around Newry, linking “the Warrenpoint Dual Carriageway to the A1 Dublin/ Belfast Road“.

Such a bypass is a very good idea and, of course, far better than the insane Narrow Water handsacrosstheborder project. But the new road must cross  the Newry River and the Newry Ship Canal, and I would be vastly surprised if there were any economic justification for the cost of an opening section or for the disruption that each opening would cause to traffic. Certainly six or twelve sailing vessels would no longer be able to reach the Albert Basin in Newry, but the greatest good of the greatest number should surely prevail.

I can’t see that the absence of sailing pleasure craft from Newry would in any  way diminish the heritage or historic value of the ship canal or the basin, and they are of course entirely irrelevant to the stillwater canal.

A spokesman from the Inland Waterways Association of Ireland” says that

The IWAI was formed in 1954 to stop the building of low bridges on the River Shannon. Fortunately this campaign was successful otherwise there would be no hire boats on the Shannon today. Think of the loss of revenue. This should be a lesson to the bridge builders in Newry.

This is rubbish, for two reasons. First, sailing vessels on Carlingford Lough are never going to be available for hire on the Newry Canal, so their inability to reach Albert Basin would have little effect.

Second, the IWAI campaign on the Shannon was notably unsuccessful. Instead of swivelling bridges that would allow masted vessels through, the Shannon now has fixed bridges (Banagher, Shannonbridge, Athlone) and lifting bridges (Roosky, Tarmonbarry) that lift enough to allow motor cruisers through, but not enough for sailing vessels.

Ruth Delany [in Ireland’s Inland Waterways: celebrating 300 years Appletree Press, Belfast 2004] says that the IWAI Shannon campaign resulted in there being a minimum clearance of 4.3m on the Shannon, which is a long way from the 35m that the Newry & Portadown folk are seeking. The only Shannon bridge providing that clearance is Portumna, a swivel bridge, which (unlike the others mentioned above) was not — or its ancestor was not — built by the Shannon Commissioners.

By using the Shannon as a model, the N&P folk have actually weakened their case: the 9m clearance suggested for the Newry bypass is more than twice what the Shannon provides.

 

Trigonometry and obfuscation

Every so often Waterways Ireland (whom god bless and preserve) sends out a Marine Notice to warn people of sporting activities, so that they can avoid them, and of one or other of the hazards of the navigations. One such, No 68 of 2016, issued on 9 June 2016, says (inter alia):

The attention of all is drawn to the dangers associated with overhead power lines in particular sailing vessels, sailing dinghys and workboats with cranes or large airdrafts.

Vigilance is required especially in the vicinity of slipways and dinghy parks, while voyage planning is a necessity in order to identify the location of overhead lines crossing the navigations.

ESB Networks emergency number is (353)1850 372 999 and Northern Ireland Electricity Networks is (44) 0800 616 817.

Then on 21 July 2016 Waterways Ireland issued Notice No 89 of 2016, which was specific (as far as WI is concerned) to the Northern Ireland navigations. Extracts:

Many sailboats have masts of 9m (30ft) or more and, as most of these masts are made of aluminium, they are an excellent conductor of electricity. If an aluminium mast or rigging come into contact with or too close to power lines, it could result in a fatality.

NIE Networks advises all boat owners to take some simple precautions to stay safe.

  • Plan your route carefully when transporting your boat to or from where it is being launched, making sure you have adequate clearance under overhead power lines. When you are stepping the mast or erecting long aerials, be sure to do so in an area totally clear of overhead power lines.
  • Once out on the water, if you are sailing on inland waterways or near islands or headlands, you should still look for overhead lines as they do cross over waterways. You must ensure that your mast or aerial has proper clearance from any power lines.
  • Always check your charts when underway to ensure you are aware of the location of overhead power lines.

In order to avoid hitting an overhead power line with a mast, it would be useful to know how high off the water, perhaps at Ordinary Summer Level, the power line was. Then you could subtract from that the height of your mast, and some safety factor, and decide whether you could safely sail under the line.

If you don’t know how high the power line is, you have to resort to trigonometry. My recollection of these matters has perhaps faded a little, but as I recall you stand a small boy of known height on your cabin roof and, with your eye level with his feet, you measure (a) the horizontal distance from his feet to your eye and (b) the angle from the horizontal to a line from your eye that touches the top of the boy’s head and the bottom of the power line. Then the small boy falls off the roof, you have to tack, your pencil falls overboard and it all seems much more difficult than finding the height of a tree. And of course you can’t measure the distance to the power line without sailing up to it, which is what you’re trying to avoid until you can decide whether you can safely do so. [Note: this paragraph is not to be used for navigation.]

Life would, therefore, be much easier (and safer) if you knew the minimum clearance under the power lines. Happily, NIE Networks is happy to tell people what it is; I emailed and a speedy response including this:

The clearance on all NIE Networks overhead power lines which cross over navigable waters is 10.5m (lower bank to line or earth). All overhead power lines are marked on navigation charts for the Erne and Lower Bann waters.

However, it should be noted that this is the clearance for NIE Networks overhead power lines and applicable to Northern Ireland only. Clearances for overhead power lines in the Republic of Ireland may be different and would require confirmation from the Electricity Supply Board (ESB).

Big it up for NIE Networks, then. But over several years I tried unsuccessfully to get the ESB to give me the equivalent information for lines crossing navigable waterways in the republic; it would not do so. Without that information, boaters cannot “ensure that [their] mast or aerial has proper clearance from any power lines”, so ESB’s advice is useless blather.

It is some time since I last asked ESB for information, and perhaps it has since been made available, but I see no sign of it on the ESB website. I would be glad to hear from anyone who can supply reliable information.

ESB and the Shannon

I wrote here that I had written to the ESB, on 27 May 2015, to ask about navigation on the Shannon from Castleconnell downstream. One month later, I have not yet received a reply.

I did hear this weekend that ESB had contacted certain boat-owners to inform them that they were not to moor to the ESB embankments between Portumna and Meelick. As a riparian landowner, ESB is no doubt within its rights, but it would be interesting to know how much of the bed of the Shannon it claims to own in that area.

I have still not been able to find out, from the ESB, the clearance under its high-voltage lines crossing the Shannon (and other navigations). I gather that the ESB works on the principle that, if it provides no information, it can’t be blamed if owners of masted vessels electrocute themselves, whereas if it did provide information it might be sued. Strange that a public sector body should have such a blasé attitude to the prospect of the electrocution of the citizenry.

Perhaps if I asked questions under the Access to Information on the Environment Regulations 2007/2011 I might get replies.

 

Pumps and crisps

Thanks to Colin Becker, I have updated this page to show the location of the ESB’s third pumping station between Meelick and Portumna: I had known only where two of them were.

I have also added to the page some rude remarks about the ESB’s policy of not revealing the clearance of their cables above navigable waterways. If, dear reader, you know of a change in the policy, or if you can effect such a change, or if you know the clearances, do please let me know by leaving a Comment.

 

Mad foreigners

The August 2013 issue of Practical Boat Owner has just arrived. It has an article by Dick Everitt called “Mind your head …” in which he talks of dangers to boats from above rather than below: dangers from bridges and from electric power lines. He points out that electricity can jump to a metal mast and says:

So a safe clearance distance is given on the chart with a lightning-type symbol and in some countries a big warning sign is positioned nearby too. But do check local Notices to Mariners as long power cables can sag over time, reducing their official charted clearances.

Aren’t foreigners funny? Imagine having electricity suppliers actually telling boaters about the safe clearance under power cables! That would never happen here ….

I have spent several years trying to get ESB to tell me the safe clearances for cables across the Shannon. I thought I was getting somewhere at one stage but nothing happened. Perhaps ESB would prefer boaters to fry than risk getting sued for getting the clearance wrong.

A problem in trigonometry

I mentioned the other day that extensive searches of tinterweb had failed to find any data on the heights of overhead power lines above the Shannon and that I had been forced to resort to the telephone.

I am pleased to report that the ESB expert duly rang me back today, and further pleased to report that he had himself measured the height of every cable over the Shannon. Oh joy, oh happiness, I thought. But not for long.

The ESB, it seems, does not reveal the actual height of power lines above the water. This, if I understood the reasoning correctly, is because the water level varies and a boat-owner might not understand that, hit a line with a mast and then sue the ESB [where “ESB” means “electricity transmission or distribution operation”]. I have been told that a boat-owner in coastal water did just that (presumably between the mainland and an island) and that the lawyers have advised ESB to take no further risk; I would welcome information about the incident.

So, if you want to find the height of a power line, you’ll need to polish up your trigonometry (and then relate the height to Ordinary Summer Level). But the ESB does supply the information to one organisation that makes charts: the United Kingdom Hydrographic Office. That’s OK for coastal charts, but the UKHO (to the best of my knowledge) has not surveyed the inland Shannon since 1839, and I don’t think its inland charts have been updated since then. It is possible, of course, that the UKHO supplies the data to other (electronic or paper) chart-makers; I have emailed them to ask.

The quest continues again. More info when I get it.