A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Navigator's Vision,Day or Night.
From: Greg Rudzinski
Date: 2009 Oct 11, 12:55 -0700
From: Greg Rudzinski
Date: 2009 Oct 11, 12:55 -0700
Byron, Thanks for the sub celestial observation description. How did subs use sea mounts for DR and positioning? Greg On Oct 11, 8:45�am, QMCM
wrote: > On Polaris Subs we had two periscopes one for general use and one type > 11 to give azimuth bearing accuracy needed for the SINS while on > surface, the general use was for Navigation and all other use. The > orders were to proceed undetected; we never broke or surfaced during > the 2.5 month. If we detected another ship we cleared away from the > area. Once we went down, we had a huge area that we hid in. There was > no reason for anyone to know where we were and each patrol was made > with no thought but to remain undetected. 3 Sins were the main > Navigation means but they were continued in check with one another and > the personnel were well trained to monitor them. Any more would be top > secret they may use the same procedures > today? > �The Standard Navy Sextant was adequate for general Navigation �David > White Company Mark II, 3 power, 10 degree true field. I did see other > sextant�s with large lens and more power, outside the navy. �On the > SUB all navigation activity was in a Navigation Center down in the > sub. > I did use the periscope �SCAR GEAR,� that I remenber had a gyro input > and printed out each shot. �Analyzing Sextant Sights. I used SCAR GEAR > on the SSBN Abraham Lincoln and a bubble sextant on a Liberty Hull. > The Scar Gear is an artificial horizon in the periscope, much like the > bubble sextant. In rough sea with both, the observed body moves > violently across the cross hairs, making the Observation open to large > random errors. The suggested practice is to use an average of many > shots of each body to get one acceptable observation for each body or > star. After some unacceptable use of the gear, I decide to try another > approach to find the best raw shot from a large number of individual > shots �To find the Best shot among the many you need a reliable > reference to judge the ever- changing time and elevation of each shot. > You must reduce work of each sight to a simple, but easy way of > elimination (random) and many shots to one best shot. I concluded that > a better solution to the average would be to plot the individual shots > on graph paper with a time line (at the bottom) and a slope that a > body is traveling upon. This slope would be a systematic reliable > reference line for each shot judgment. The time of the first shot > would be the start of a 4 minuet time line and also time to compute > Local Hour angle LHA for table entree for tabular altitude (tab Hc) of > the body. The far base of the horizontal time line of four minutes > would start with the LHA and end with LHA1+l, four minutes of time to > arc, [one degree] or LHA297 and LHA298. > At right angle to the time line would be the raw Hc tab. out of the > tables, the bottom is LHA 297�s Hc 46 38.1, the right angle at the top > would be 298�s Hc 47 17.1. This SLOPE (STAR TRACK) would be drawn from > the left beginning of the time line (LHA297 Hc tab. to the top LHA > 298Hc tab four minutes later. Once the graph is completed and each raw > shot!Hs is plotted in terms of time and Hs height the Hc slope can be > moved parallel to its self among the plotted Hs�s on the time line for > best agreement. Each Hs shots should be easy to identify as systematic > or random. A selection of one time and Hs shot can then be completed > to height observed and to line of position for the fix. (If your Hs > don�t match the Hc on the vertical, add or subtract an amount to fit, > move the slope to select you best shot, than use the original Hs. The > slope could be corrected for speed and direction during the four > minutes traveled. In order to accommodate other star�s slopes, any > time and Hs could be used to Finnish the sight and find the best shot. > Best for a slow moving ship. > > On Oct 7, 10:26�am, Anabasi...---.com wrote: > > > This also works very well when trying to see running lights at a fair � > > distance. �My use of this technique allows me to pick up ships at 15-20 nm �from > > the bridge well before most of the other watch standers can see the �ship. � > > Generally in good visibility, I can see the running lights soon �after they > > pop over the horizon. > > > Jeremy > > > In a message dated 10/5/2009 2:21:55 P.M. Eastern Daylight Time, � > > > byron...---.com writes: > > > Navigator's vision at day and night. > > The way you use �your eyes at night is different from the way you use them > > during the day. With �normal day vision, you train your eyes to look > > directly at the target. If you �catch something out of the corner of your eye, you > > automatically move your �eyes to center on the target. Once you have done > > so, you can see the target �clearly in color, and detail. In the dark, > > however, instead of directing your �vision at the area you desire to see, you must > > learn to use off-center vision �for a very dim light or star. �The first > > step in training yourself in �night vision is finding a location free of normal > > white city �lights, � Perhaps your backyard or better at sea. Wait until > > your �eyes have adapted to the dark; this can take about 15 to 20 minutes. At > > this �point the sky is black, some stars are bright, or some dim and you are > > aware �of your surroundings. Your eyes are accustomed to the dark. If you > > need a �light to read/write or see a star finder (NAVLIST 9471) use a red dim > > light �only. �Look at the sky and find a bright star. Now slowly move your > > eyes �until you see, or think you see, the dimmest star out of the corner of > > your �eye. Look directly at the star. If it is a very dim star it will > > "disappear" �when you look at it and won't reappear until you move your eyes and > > "look" at �it using the off-center technique. It may well be fuzzy and lack > > color. But �you do see it. What is happening here is that you are seeing it > > with your �peripheral vision. Practice this off-center technique until you > > are �comfortable picking up even the dimmest star. �Binoculars can help make > > �some of the dimmer stars very bright. But other stars will disappear when > > you �look directly at them, even with binoculars. At sea at night, relax and > > move �your eyes slowly just a few degrees around the sky or the horizon. If > > you �think you see a light, use the off-center vision technique to isolate > > your �target. If the light is very faint and disappears, use a slow, > > off-center eye �motion to pick it up again. Then use your binoculars to pick up any > > color �details. Practice this off-center procedure until you are proficient > > in seeing �things at night. When you are in the darkness, only a trained > > eye can produce �the correct information quickly. In the day time when you > > want that good �horizon for a star or planet before dark thickens the horizon > > try the �"Vertical Sextant" NAVLIST of Sept 28. � --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To unsubscribe, email NavListemail@example.com -~----------~----~----~----~------~----~------~--~---