Re: Night Vision (was LED for running/navigation lights)

I recall from my pilot training that the red light to preserve night vision is an old wive's tale (old sailor's tale?). I believe the theory is that either the rods in the retina are less sensitive to red light, and thus red light is less damaging to night vision. As I understand it, scientists now believe that it's the intensity of the light and not the wavelength that is important, and so any dim light will do. Avoid a bright point source if possible, which means using as much of a diffuser as is practical to still provide enough illumination. Keep in mind that it takes the eyes just 10 to adjust from dim to bright light, but it takes 30 to 45 minutes to adjust from bright to dim. This is because your eyes actually have to manufacture a chemical required for dim light vision. Also keep in mind that the cones are concentrated in the center of your retina; these are the ones that see color and detail. The rods are the ones that work in dim light, and there are very few in the center of your field of vision. This is why you should keep a constant sweep going when keeping watch at night, and not fixate in any one direction. You may not see objects when you look directly at them, but only when you are looking off to one side or the other. (Try this with the Pleides - the Seven Sisters - some dark night. You can't see them when you look straight at them, but they will appear in view if you look to one side or the other.) Alfred Poor 1969 Cal 29 #132, "Pentaquod" <http://groups.yahoo.com/group/Cal_Boats/message/5456;_ylc=X3oDMTJycHY1OGJhB F9TAzk3MzU5NzE1BGdycElkAzE2NDg1Njk1BGdycHNwSWQDMTcwNTA2NTc5MgRtc2dJZAM1NDU2B HNlYwNkbXNnBHNsawN2bXNnBHN0aW1lAzExNjk0NzE1MzM-> Re: LED for running/navigation lights Posted by: "Randy Alcorn" <mailto:sa… [at] yahoo.com?Subject=%20Re%3A%20LED%20for%20running%2Fnavigat ion%20lights> sa… [at] yahoo.com <http://profiles.yahoo.com/saylorran> saylorran Sun Jan 21, 2007 9:00 pm (PST) Hi, I am assembling a Flying Tiger 10 meter for this seasons races. It came as a boat in a box! What a great experience! All lights are LED. I am surprised the nav station has a blue light. I gues I was raised with red lighting to protect the eyes at night. Randy CAL 2-29 Out Patient Channel Islands Ca

Alfred Poor wrote: > > I recall from my pilot training that the red light to preserve night > vision is an old wive's tale (old sailor's tale?). I believe the > theory is that either the rods in the retina are less sensitive to red > light, and thus red light is less damaging to night vision. As I > understand it, scientists now believe that it's the intensity of the > light and not the wavelength that is important, and so any dim light > will do. Avoid a bright point source if possible, which means using as > much of a diffuser as is practical to still provide enough illumination. > > > > Keep in mind that it takes the eyes just 10 to adjust from dim to > bright light, but it takes 30 to 45 minutes to adjust from bright to dim. > This is what I have read, also. One trick when you must use bright light during a stint at the helm is to close one eye in the bright light, using the other only. Then you have "one good eye." Chris Campbell

There was a series of Chesapeake Bay chart books (Alexandria Drafting Company?) that had many points on the Bay marked in red type. We'd go onto red night vision on the boat and all the markings would disappear. It seems the Navy did (does?) the red thing on ships. Is that true? Cheers Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Chris Campbell Sent: Monday, January 22, 2007 12:45 PM To: Ca… [at] yahoogroups.com Subject: Re: [Cal_Boats] Re: Night Vision (was LED for running/navigation lights) Alfred Poor wrote: I recall from my pilot training that the red light to preserve night vision is an old wive's tale (old sailor's tale?). I believe the theory is that either the rods in the retina are less sensitive to red light, and thus red light is less damaging to night vision. As I understand it, scientists now believe that it's the intensity of the light and not the wavelength that is important, and so any dim light will do. Avoid a bright point source if possible, which means using as much of a diffuser as is practical to still provide enough illumination. Keep in mind that it takes the eyes just 10 to adjust from dim to bright light, but it takes 30 to 45 minutes to adjust from bright to dim. This is what I have read, also. One trick when you must use bright light during a stint at the helm is to close one eye in the bright light, using the other only. Then you have "one good eye." Chris Campbell

Husar, Charlie wrote: > > There was a series of Chesapeake Bay chart books (Alexandria Drafting > Company?) that had many points on the Bay marked in red type. We'd go > onto red night vision on the boat and all the markings would disappear. > > It seems the Navy did (does?) the red thing on ships. Is that true? > My recall is that they've gone to green. Chris Campbell

Interestingly, I just ordered a retrofit binnacle light for my 30 year old Ritchie (the old one finally disintegrated) - the light was available in either red or green. Bob Andrew From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Chris Campbell Sent: Monday, January 22, 2007 2:00 PM To: Ca… [at] yahoogroups.com Subject: Re: [Cal_Boats] Re: Night Vision (was LED for running/navigation lights) Husar, Charlie wrote: There was a series of Chesapeake Bay chart books (Alexandria Drafting Company?) that had many points on the Bay marked in red type. We'd go onto red night vision on the boat and all the markings would disappear. It seems the Navy did (does?) the red thing on ships. Is that true? My recall is that they've gone to green. Chris Campbell

The Discover Channel show "Myth Busters" just did an experiment to prove or disprove the myth that pirates wore an eye patch so one eye was always night-vision ready. Often, the scientific methods used on this show are questionable. However, in this instance, the results were conclusive despite the subjective nature of how well one sees. Wearing an eye patch does provide night vision readiness while the other eye is exposed to light. One simply designates which eye is to be used for night and which for light and moves the patch from one eye to the other as required. Does West Marine carry eye patches ? Steve Urbanski Ca… [at] yahoogroups.com wrote on 01/22/2007 11:45:26 AM: > Alfred Poor wrote: > > I recall from my pilot training that the red light to preserve night > vision is an old wive?s tale (old sailor?s tale?). I believe the > theory is that either the rods in the retina are less sensitive to > red light, and thus red light is less damaging to night vision. As I > understand it, scientists now believe that it?s the intensity of the > light and not the wavelength that is important, and so any dim light > will do. Avoid a bright point source if possible, which means using > as much of a diffuser as is practical to still provide enough illumination. > > Keep in mind that it takes the eyes just 10 to adjust from dim to > bright light, but it takes 30 to 45 minutes to adjust from bright to dim. > > > > > > > > > > > This is what I have read, also. One trick when you must use bright > light during a stint at the helm is to close one eye in the bright > light, using the other only. Then you have "one good eye." > > Chris Campbell > - For more information about UL, its Marks, and its services for EMC, quality registrations and product certifications for global markets, please access our web sites at http://www.ul.com and http://www.ulc.ca or contact your local sales representative. -- ********* Internet E-mail Confidentiality Disclaimer ********** This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. UL and its affiliates do not accept liability for any errors, omissions, corruption or virus in the contents of this message or any attachments. *****************************************************************

I did a sort of Transpac of my own, commonly called a Tiger Cruise aboard a U.S. Navy frigate homeward bound from Hawaii to Everett, WA. Family of sailors are allowed onboard for the return trip. We were shown the combat room, which was very dark and lit only with red lights. My nephew reported the only time the lights were not red was when she was in port. Here she is: http://www.navsource.org/archives/07/0761.htm --- In Ca… [at] yahoogroups.com, Chris Campbell <clcampbell@...> wrote: > > Husar, Charlie wrote: > > > > There was a series of Chesapeake Bay chart books (Alexandria Drafting > > Company?) that had many points on the Bay marked in red type. We'd go > > onto red night vision on the boat and all the markings would disappear. > > > > It seems the Navy did (does?) the red thing on ships. Is that true? > > > > > > > > My recall is that they've gone to green. > > Chris Campbell >