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Sunday 24 September 2023 Dublin: 15°C
# mist-ery solved
Ever wondered about foghorns? This should clear things up
The foghorns have been blasting in Dublin this week – causing a red mist to descend for some residents.

IT HAPPENS EVERY summer in Dublin.

After a long stretch of warm, sunny weather, the coast is covered in fingers of drifting fog…

There’s more of it forecast for this morning, and it was particularly bad on Wednesday night – as the selection of tweets below demonstrates:

One tweeter (we’ll spare their blushes by not embedding their message) even sent out the following:

Any need for the Fog Horn anymore, think we’ve all established its f***** foggy.

Needless to say, it’s probably fair enough to assume most people aren’t under the impression that foghorns are there to tell the population in general it’s foggy (that’s what the fog is for).

But there were plenty of sensible questions posted on social media the other night too – like the “why so many beeps?”.

So… Why?

shutterstock_309361388 Shutterstock / Marat Dupri Shutterstock / Marat Dupri / Marat Dupri

What the fog?

Our first port of call (sorry) as we set about trying to find a few answers was Irish Lights. They look after the lighthouses, so surely the fog signals too – right?

Not so, apparently. At least, not anymore.

A helpful spokesperson said that while the switchboard had been lighting up with complaints about the noise this week, land-based fog signals were in fact discontinued at the start of 2011.

What people were hearing were ship-based fog signals.

Given the level of traffic at Dublin Port on any given night, and the fact that the blasts are designed to carry over long distances – then yes, absolutely, it would be pretty noisy.

Ask an expert

Perhaps a marine surveyor could help clear things up for us a little?

Why so many blasts? Why so loud? Here’s what Frank Jackson, a Wicklow-based surveyor and member of the Irish Maritime Law Association had to say:

“Under the international regulations for preventing collisions at sea, ships and all craft that are under way – moving in the water – are required to signal their presence in fog with a foghorn.

That signal is a prolonged blast which is six to nine seconds in intervals of not-exceeding two minutes. They’re required to do that by law.

Ships at anchor use a bell instead of a blast, he said. And the rules apply to all craft – not just larger merchant or passenger vessels.

“Fishing boats, pleasure craft, they’re all supposed to do it.

“A guy in a small canoe or a currach – if he’s not sounding then nobody knows he’s there. But at least if the other vessel is sounding the horn, then he knows it’s there.

Then what he [the guy in the notional currach] should be able to do is have some kind of horn that he can signal his presence with in response… If he hears the foghorn of another vessel, he should have something to signal back with.

19/3/2009 Heavy Fog Heavy fog partially conceals the top of Boyne Valley Bridge on the M1 in Co. Louth.

As to why the land-based signals were scrapped in Ireland?

According to the former merchant seaman:

“The [ones at the] main lighthouses went because it was felt that ships had accurate navigation capability these days to know where they are, and not to be approaching that close to the coast.

A lot of smaller craft as well would have some kind of navigation system – so it was felt it wasn’t necessary to have a foghorn… that vessels would know where they were in the fog and [would not be] likely to be running up on the beach.

The same thinking wouldn’t apply when ships are passing in the open water, obviously…

“Smaller vessels don’t have a way of tracking other vessels or detecting other vessels… A lot of small craft rely on visual observation of vessels.

When it’s foggy, they need to hear.

rathlin Irish Lights The 'Rathlin Bull' which could once be heard up to 30km away. Irish Lights

Fog signals can be “a matter of life and death” at sea, Jackson said.

And if you’re one of those people who had trouble sleeping this week amid all those blasts – you can at least be thankful the shoreside warnings were discontinued.

According to Irish Lights, one of the Great Lighthouses of Ireland at Rathlin West in Antrim once had a famous fog signal called the ‘Rathlin Bull’ which could be heard from more than 30km away.

It was discontinued in 1995 after 70 years of service. Much to the relief of its neighbours, no doubt.

Read: New rules mean all the Times Square Elmos and Spidermen now have to stay within painted rectangles >

Read: Leaving Cert weather was great while it lasted, but it looks like fog and rain for the weekend >

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