Mailport December 2013 Issue

Mailport: December 2013

Night Vision

I enjoyed your editorial (PS, August 2013) and agree with you on the importance of preserving night vision, but you missed one critical element: the color of the light. We all know that slipping a red filter into our flashlights makes them OK for use at night (as long as itís not too bright), but few know that itís not the color of the light that matters; itís the colors that are not in the light.

Red filters eliminate blue and UV light, which have the most detrimental effect to night vision. Also, while the night mode of most marine electronics does effectively eliminate blue wavelengths of light, few consumer devices (e.g. iPhones) have this ability. has filters designed for various electronics, but these can get pricey. The best solution is to avoid using anything that contains blue light. (Note: All white light contains wavelengths of blue.) If however, you canít resist using your iPhone, or need to turn on those bright spreader lights at night, a cheap and (mostly) effective solution is to wear Blue Blocker sunglasses or safety glasses with a yellow tint.

John Konrad
Tanton 43
Morro Bay, Calif.

Next: Rescue Magnet

Comments (1)

Rescue Laser Flares have been on the market since 2001 offering a safe alternative to pyrotechnic emergency signaling device. The Rescue Laser Light is available for only $99 and offers 40 hours of signaling before replacing the battery and includes a limited lifetime warranty. See to view all three models - all of which are under $200!

Posted by: Greatland Laser | January 17, 2014 2:13 PM    Report this comment

New to Practical Sailor?
Register for Free!

Already Registered?
Log In