Rhumb Lines August 2013 Issue

Seeing the Light on Night Vision

A few weeks ago, I found myself in the desert at night and reflected upon how much the wide expanses of sand and rock in the American Southwest resemble the sea—especially after the sun has set.

Away from the loom of the lights of Moab, Utah, my wife and I stood in an empty parking lot looking to the east, where the pyramid peaks of the La Sal mountains were silhouetted by the light of the full moon, still invisible below the horizon. We’d arrived to Arches National Park at night, driving through the blackness, following our headlights to the third or fourth pullout on the winding road into the park. We missed the sign identifying the pullout, so the geographical feature that the viewpoint was meant to serve remained a mystery.

I looked to the west, where I presumed some dramatic rock formations loomed and saw only the vague shapes of hill or a cliff.

We had many nights like these in the far Pacific—moonless nights before our eyes had fully adjusted to starlight, or nights when dark squalls blotted out the moon. Our running lights were kerosene, yellow flames that flickered behind smoky red and green Fresnel lenses, at times so dim I worried whether anyone could see them—more reason for me to concentrate on preserving the keenness of my own eyes. I remember watching the colors from our running lights expand as my vision adjusted to the night. It never failed to fascinate me how pinpoints of light on the edge of our galaxy could illuminate the sails, the mast, and even the tip of our bowsprit. If there were a ship out there, I had no doubt we’d see it.

I wish I could say that it was solely by choice that we sailed through the night mostly by starlight. We were forced by circumstances. After serving so well while we cruised in and out of foreign ports where new batteries could be easily obtained, our house batteries inconveniently decided to peter out mid-Pacific (of course). We reserved our meager amps for essential tasks, and relied heavily on our oil lamps.

It was probably a good thing we didn’t have the luxury of a big battery bank and some bright deck lights to flick on whenever a sail fluttered or halyard rattled. I hate to think of all the things that might have passed unnoticed until it was too late: the dark shape of a log floating east of the Galapagos, the white line of breakers on a poorly charted reef near Aitutaki, the single dim all-around light of a Taiwanese fishing boat east of Tonga, or the brilliant phosphorescence trails and splashes made by spinner dolphins (hundreds, or so it seemed) leaping above the waves on a moonless night.  

Even today, when the boats I sail are well equipped with spreader lights as bright and energy efficient as those we review in this month’s issue, I think twice before reaching for the switch.

Although we can regain most of our night vision within 10 to 15 minutes after being exposed to a light, it takes about 30 minutes for our eyes to fully adapt. One need only be caught night-blinded once to realize how critical it is to retain our scotopic vision at sea. As Shakespeare wrote: “He that is stricken blind can not forget the precious treasure of his eyesight lost.”

A few minutes before the moon rose from behind the La Sal range, with my eyes finally functioning at optimum level, I looked back to the west and realized where we were. A high ridge called the Great Wall loomed over us, as big as any freighter. Thankfully, it wasn’t going anywhere that night.

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