You might think you hear it when you can't.
You might not hear it when you should.
You often hear it when you shouldn't.
Consider the foghorn, an unreliable prosthetic for the blinded, an aural illusion for the grounded.
Vibrating the eardrums of thousands more people than actually need it - while those who use it need it less every day - the foghorn at the end of Crescent City Harbor's west breakwater is actually more an icon of the mistier fringes of nautical life than it is a navigational aid.
People who spend time anywhere near Crescent City know that when they can and do hear the foghorn, it's inescapable. It's there about every 10 seconds. Many find it comforting, like the lapping of waves (another rhythmic, briny sound coast-dwellers are fond of). A quieter number of the population finds its regular tooting to be too loud and too often, an itch they can't scratch.
Either way, Crescent City's denizens must live with it. Few rhythms in their lives - maybe just their breath and pulse - are more constant, frequent or omnipresent as the foghorn when it's audible, so much so that the ways people become accustomed to it can play tricks on their minds.
Another Del Norte foghorn is illustrative: In a 2007 Triplicate interview with former St. George Reef Lighthouse keeper Byron Horrocks, he recalled a time when a thick fog kept its lighthouse foghorns running for 11 days.
"I went out there one time, and I said, 'Oh golly, the fog lifted. I'm going to turn the foghorns off,' and one of the other fellows said, 'I turned them off 20 minutes ago.'"
Horrocks was so used to its pulse that he was hallucinating its sound after it finally stopped.
My own experience with foghorn illusions runs the other way. A few years ago a friend from out of town visited Crescent City for the first time. One night at my home he asked me, "What's that sound?"
"What sound?" I asked.
"I don't hear it."
"Well it just stopped. But I keep hearing it. Wait a second," he said.
We waited a few seconds.
"There. There it was again."
"I still didn't hear anything," I said.
"How can you not hear that? It's like a andhellip; I don't know how to describe it. Like a andhellip; a andhellip; beeping maybe. You seriously can't hear that?"
I seriously couldn't. I was as curious as he was and continued listening for it with him. It took awhile.
"OK , there it was again," he said for the sixth time after a minute's concentration in vain. "Did you hear that?"
And finally I did. Or rather, finally Ilistenedto it. My ears must have heard it, but my brain wasn't listening. I had completely tuned out the foghorn to the point that I didn't consciously register it even when I was trying to pay close attention.
Such is its power to deceive.
Another matter entirely is its power to elude.
The Crescent City Harbor foghorn lies at the far end of the jetty where the harbor ends and the Pacific Ocean begins. There stands an approximately 40-foot-tall steel tower painted white and topped with a rotating light.
To keep out wanderers who haven't been jettisoned from the jetty by its often crashing waves, the base's ladder starts halfway up, beyond the reach of even the tallest wall walkers. The ladder ends at a platform about 10 feet below the peak, and on it there is a fiberglass circular structure 3 feet tall and 18 inches wide, domed at the top and slotted around the midsection. This is the foghorn proper. (From most angles in Crescent City all but the foghorn's dome is obscured by a large aluminum box containing a battery that serves both the horn and the light.)
The foghorn's guts are rather simple: a circuit-board in the dome and a "driver," which, although it employs a magnet 140 times stronger than a refrigerator's, is not significantly different from any other speaker, be it the woofers and tweeters in a home stereo system or the miniature variety in headphones: the magnet's force vibrates a diaphragm, creating compression waves - sound - that are projected out of the middle of the foghorn's structure through slots between vertical, fin-like structures.
The result is Crescent City's familiar foghorn sound, a crisp, electronic 390-hertz tone at close range and, farther away, a more ghostly G-note that glides up and drifts off.
The horn is, in fact, an Automatic Power Inc. fog signal, model no. FA-232, which is widely used by the U.S. Coast Guard. The standard tone of the FA-232 may be "converted to an electronic bell or a gong tone to offer a more pleasing aural sounding horn in highly populated areas," a manufacturer's press release states. Make of this implication about Crescent City's population what you will.
A long half-mile
Sound is decidedly unsound in the ways it will or won't travel.
The spec sheet for the FA-232 says its range is half a mile, but Crescent City's landlubbers know that's preposterous. It's not uncommon for the horn to be audible at least three miles inland. Conversely, sometimes it's hard to hear from less than half a mile away.
It would be easy to assume that the foghorn is simply not switched on when one doesn't hear it, but that's not the case. According to personnel at Coast Guard Station Humboldt Bay, Crescent City's foghorn is on all the time, year round.
There is a two-part explanation for this half-mile mystery. Part one is that this "nominal range" of half a mile isn't so much nominal as minimal. Part two is why half a mile is near the minimum range.
The "nominal range" of a foghorn is defined by the International Association of Lighthouse Authorities as "the distance at which, in fog, a lookout positioned on the wing of the (vessel's) bridge has a probability of 90% of hearing the signal when subjected to a noise as defined by IALA as being equal to or in excess of that found in 84% of large merchant vessels."
In other words, while half a mile isn't the worst it can do if the weather is bad enough and ambient noise from wind, waves and water vapor is high enough, the range can also be much longer if the weather is fair and the listener is not on a big ship with a running engine. Temperature and wind direction can also influence the speed and range of sound. On land, walls can misdirect sound. Traffic can be sufficient to drown out the foghorn - as can rain - and in my experience it's more often audible during the quiet of the night.
The American Practical Navigator, a federally produced bible of marine piloting, puts things bluntly - almost with a hint of a snicker - when it summarizes the reliability of "sound signals" like buoy bells and foghorns:
"The mariner should never assume:
"1. That he is out of ordinary hearing distance because he fails to hear the sound signal.
"2. That because he hears a sound signal faintly, he is far from it.
"3. That because he hears it clearly, he is near it.
"4. That the distance from and the intensity of a sound on any one occasion is a guide for any future occasion.
"5. That the sound signal is not sounding because he does not hear it, even when in close proximity.
"6. That the sound signal is in the direction the sound appears to come from."
So good luck with that, mariners.
Increasingly, mariners are turning to more reliable navigational tools.
"With today's technology, I can't speak for all of the mariners, but more and more of them are using what's called chartplotters, and it's just basically an electronic roadmap like the Garmin (GPS device) you've got in your car," explained Boatswain's Mate 1st Class Brian Luman with the Coast Guard's Aids to Navigation Team Humboldt Bay.
Despite diminishing need for it, Luman's team services Crescent City's foghorn (and five others along the North Coast) typically once or twice a year.
In harmony with the Coast Guard's motto, "Semper Paratus" (Always Ready), the team will go out and work on aids to navigation whenever a vital component breaks down.
Although ANT HumboldtBay normally services Crescent City's foghorn in the summer, it made an impromptu trip Jan. 11 (when waves were calm) to fix the tower's solar-powered battery, which had recently stopped functioning as well at night as it did during daytime.
"With seas crashing over the breakwall, we just can't get out there most of the time. We wait for calm weather and then carry all our gear across all that riprap to service the signal," Luman said.
The team hikes down the jetty with three to five members because of all the gear they have to take with them. There's climbing gear to get up the tower and equipment to repair or replace every component on it: foghorn parts, the solar panel, the battery and the light at the peak - enough stuff that they won't have to hazard two trips.
Perhaps with technology's advance, someday the Coast Guard will no longer service the foghorn or the light on the jetty tower, just as it no longer keeps the light on at Battery Point Lighthouse, which is now operated by Del Norte County Historical Society for cultural and not navigational purposes.
If or when the day comes when the foghorn isn't needed, will Crescent City decide to keep its familiar sound playing for sentimental reasons or will the locals choose to live without it, all the better to hear the roar of the ocean and sea lions' commotion?
For now, when you hear it, think of those it aims to serve, who in the past week embarked on their busiest time of year as crab season opened.
Always on, "always ready" to help, the foghorn is, if nothing else, a reminder that people's lives matter. The minor inconvenience to the many is outweighed by the lives of a few, who may at times ply the waters blindly searching for safe passage home guided by the imperceptible whims of a sometimes perceptible sound.
Reach Assistant Editor Matthew Durkee at email@example.com.