Lighthouses - Purposes

The two main purposes of a lighthouse are to serve as a navigational aid and to warn boats of dangerous areas. It is like a traffic sign on the sea. Here are five other facts about lighthouses you should know. Lighthouses are painted differently to help mariners identify them during the day. For example, a lighthouse may be painted all white if its surroundings background is dark. The red and white stripes help the mariner identify the lighthouse if it’s up against a white background, such as cliffs or rocks. The height of a lighthouse takes into account the curvature of the earth, so the higher light above MHW (mean high water), the further away it can be seen at sea. But the light should not be so high up that local sailors will not see it. This is why you will frequently get shorter lighthouses on the top of cliffs and taller lighthouses built nearer the water surface.

Skerries Lighthouse

Lighthouses in fairly close proximity to each other have different flash patterns to allow the mariner to identify their location. Some lighthouses in different geographical areas share the same flash patterns. Originally lighthouses were lit with open fires, only later progressing through candles, lanterns and electric lights. These days, lighthouses are run by machines and remote monitoring. The automatic sensors decide if there is extra moisture in the air, and if so turn on the fog signals. Radio signals are used to communicate with the ships. But when the technology was not so advanced the lighthouses were run by lighthouse keepers. Lighthouses allow dangers to be avoided and a ship to navigate accurately. In the daytime they are day marks, each very identifiable, and at night they give out their own characteristic light code identifying not only where they are, but who they are, so the ships navigation officer can tell one from another.

Port Ellen Lighthouse

From the Lighthouses, Lightships and Buoys they can see, the ships officers can accurately plot a ship's course. The ship's course can be continually updated by taking compass bearings on two fixed navigational points marked on Admiralty charts.  Most lights are arranged so a ship can see two or more at a time, with the exception of deep sea lighthouse towers marking rocks laying in wait to wreck any boat that gets too close. There are also wrecks, sand banks and other hazards to be avoided, with safe channels around some coastal sections and routes into and out of port. With far heavier sea traffic now, collisions have to be avoided, and this is partly achieved by putting shipping in different directions in different lanes.

St Mary's Lighthouse

Today a shipping disaster is rare, but before lighthouses and other aids were common, there were hundreds of ships wrecked on our coasts each year. How long will we have lighthouses for, is a question we cannot answer. With new technology, most deep sea vessels have several electronic navigation systems, and so conceptually can navigate from this and charts. In recent years, radio beacons set up around the coast - originally by Decca - have been used to transmit individual navigational signals and even more recently satellite navigation has been developed as a very sophisticated form of positioning vessels. 

These systems require interpreting skills to plot courses and are prone to error and system failure.  Atmospheric conditions can also affect their accuracy at dawn, dusk and during fog. In addition it is always the risk that terrorists or others could interfere with the radio signals and put these out of operation for period. So without the back up of lights, visual marks, we could have a series of shipping disasters that would make historic losses look small. Generally its only the commercial vessels which are equipped with sophisticated satellite equipment, and many recreational craft, smaller fishing boats and lifeboats still rely largely on existing lights and marks.

In researching and writing up the location guides there have seen a number of occasions has considered lights to no longer to be necessary, on the basis that later technology is making them obsolete, and its only local protests that have persuaded them to keep them operational, although usually at a reduced power. Lighthouses prior to de-manning also provided another service now lost, looking out for ships or people in difficulty, this they did in cooperation with a large number of coastguard stations and between them most of the coast could be watched. In addition to the demanning of lighthouses and removal of most lightships most of the full time coastguard stations are now closed. There is a new voluntary group attempting to fill some of this vacuum but realistically its unlikely that a large percentage of the coast will be watched again.

The technology we have will continues to get better, more reliable and more people will both have primary and small back up systems, and while for the foreseeable future you will want harbour buoys, the future of other lights is less certain. The driving force, supplier of most of these new electronic enhanced navigational toys to the lighting authorities is a company called VT Communications Ltd. This was the company that was called Merlin Communications and was created by the privatisation of the BBC World Service transmission sites. They are now a part of a public company, VT Group,  and VT Group are currently in the course of being taken over by another company Babcock International Group PLC,  who are already a major supplier in these areas.

But what if there is a bug in their software, a volcanic or other disturbance, a sun flair, meteorite or a whole range of other unknowns disrupting radio signals. What if terrorists or criminals should block radio signals or just flood the waves with static or rubbish. What if these electronic aids stopped working, then without the lighthouses we would have the biggest collection of shipping disasters ever seen, we could not feed the people of Britain, as Britain could become a 'no go' area for shipping. In my view we are not likely to see the sudden announcement of the closure of all lighthouses, but many of the small units, those that look like metal structures on legs, are likely to go, and when they are not required these are likely to be scraped and lost.  If lucky, a few may go to museum sites. A lot of the smaller coastal lighthouses are also likely to close and be sold for conversion to homes with good views. Some island sites will be sold to nature preservation trusts as observatories. The major structures are eventually likely to have their lights turned off but remain for a period later.