I recently ran across the story of the lighthouse that wouldn’t change its course again and got to thinking. While I obviously know this story isn’t true, is it possible that it could happen? If not, why not? If it could happen, isn’t it rather likely that something similar has happened at some point?
I guess what I’m looking for is the protocol for communicating at sea. How does a lighthouse identify itself in a situation like the one described in the story?
I believe all lighthouses have an ID that they use when broadcastinig on the radio. So there is little chance this sort of thing could happen if correct radio protocol is being followed (which it usually is).
Plus, charts have lighthouses marked, so even if you’re off in your plotting by a couple of miles it wouldn’t be liekly that you wouldn’t know that there was a lighthouse nearby.
As a Naval Officer, I can tell you that I have never communicated with a lighthouse. These days with satellite navigation that can tell me where I am within a few feet, I don’t use much else.
Having said that, each lighthouse has its own signature. The time in seconds that the light is on, and how long it is off, and how often it repeats the cycle identifies it from other lighthouses in the area. But that was the point. In days of old, you could tell roughly where you were without contacting the lighthouse. Additionally, a lighthouse looks nothing like a ship a sea. The story about the aircraft carrier and lighthouse is just that, a sea story.
Actually, it’s even simpler than a radio protocol to debunk. Lighthouses look different than ships. Running lights on ships are steady. Lighthouses, and beacons in general, flash in some identifiable manner.
And to aid in piloting different lighthouses flash in different ways. For example, the light may be on most of the time but “occult”, that is turn off, every five seconds. Periods of occultation are listed on charts so you can figure out which lighthouse it is you’re looking at.
Lighthouses nowadays don’t do much, except light. At least in the U.S. I know that Boston Light is still manned, beyond that I’m not sure any others are. (At least not by the CG) Some lights are rigged to provide automated information, such as equipment status and weather reports, but these reports are generally sent to the CG unit responsible for its sevice, or NOAA for weather. Some lights are configured with “RACONS” which will show up as a distinct series of dits or dahs on your radar. Some may even still broadcast radio navigational signals, but I’d be surprised as that form of navigation is going the way of, well, the lighthouse. With the advent and GPS, it’s reliablilty and affordability, the old ways of nav are going the wayside.
To be honest, the only reason we still have so many lighthouses today, is because of our love affair with them. In reality, they are costly, inefficient and sometimes dangerous to maintain and service.
Any signal that a lighthouse puts out for aiding navigation, light characteristics, racon info, radio nav signal & freq, fog signal, etc. is published in the “Light List”, an annual publication which lists all aids to navigation in use for the mariner. All prudent mariners, and certainly all professional ones will have this pub.
So, nobody really communicates with a lighthouse, save Boston Light perhaps. If your on a ship, and can’t tell the difference between a lighthouse and another ship, you probably shouldn’t be driving that ship.
It’s a neat story, though. When I first heard it, it was a Navy Captain (ship) talking to Coast Guard seaman (lighthouse). Go figger.
Chandeleur, who used to maintain 4 lighthouses in Penobscot Bay. 
So the main reason this never happens is that the first contact with a lighthouse you have is visual, and the lights make it clear that it is indeed a lighthouse and not a ship?
Exactly. Basically, ships’ lights are steady, while lighthouse lights blink. In addition, ships are lit so that other ships can quickly determine the orientation of the ship – whether it’s cutting across your path or is coming directly at you. Anyone who could mistake a lighthouse for a ship would be too incompentent to ever be promoted to Ensign, let along Admiral.
Not necessarily, but usually. Your first contact with a lighthouse may be radar. It may even be audibly, depending on the present visibility, rain clutter, lighthoused location, etc. But lets take visual contact for a moment.
A light in a lighthouse will basically do one of four things: Flash (off more than on) Occult (On more than off) Isophase (on and off same period of time) or it’s Fixed (constant light). For any light characteristic other than fixed, when you see it from afar, you pretty much know you’re dealing with some type of lighted aid (maybe). If it’s fixed, it may be the masthead light of another ship or sailing vessel. These lights will be seen long before you see their other lights. Or it could be anything. It doesn’t really matter because what happens on a proper watch, is that as soon as you see a light on your horizon, you attempt to identifiy it with what you have at your disposal (Charts, radar, nav pubs, etc)
When you see a light on your horizon, you’ll check your radar in that direction, and see whats there. If it’s a lighthouse on land, you’ll see just that - land. You’ll look at the chart in that area, look at all the aids in that area, and match the light you see with the characteristics of the lights that are on the chart. All lighted aids have the light characteristics listed right on the chart with the aid. From the time you see a light on the horizon, until the time you can positively identify it as a lighthouse, should only take a minute or two, maybe sooner.
You see a light, and a lone blip on the scope, and nothing charted in the area, then you can start to assume you’re dealing with a vessel of some sort.
The legend in question is pretty ridiculous because to believe it, one would need to assume that a modern day Navy ship is sailing around land without looking at any charts, pubs or radars. :eek:
Your first contact with a lighthouse may indeed be audibly, if it has a fog signal. Heavy rain or snow can blind a radar pretty good, not to mention your eyes. Mariners in unfamiliar waters are especially cautious in these situations. But if you have a chart, you’ll be listening hard for that lighthouse; you’ll want to know exactly where that thing is at all times.