NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: HO 211 Umland version
From: Paul Hirose
Date: 2002 Jan 25, 2:15 PM
From: Paul Hirose
Date: 2002 Jan 25, 2:15 PM
I finally took a good look at the version of the HO 211 sight reduction table that Chuck Griffiths pointed out for us. Its creator, Henning Umland, has made the table available for download on the Web. http://home.t-online.de/home/h.umland/index.htm Some of his table's features are arguable. In my opinion there are an excessive number of significant digits. For example, in the A column, from zero to 50 degrees, there's at least one more significant digit than needed for interpolation to .1 minute. At 77 45 the A values change from integers to numbers with one decimal place. However, they could remain integers all the way up to 85 degrees and still allow reading to .1 minute. I was pleased that this table always keeps the A and B columns in the same places, just as Ageton did. Umland also gives you all the digits for each table entry. By contrast, the Bayless tables switch A and B to save space, and omit digits if several entries in succession begin with the same digits. The first trick cuts the table size in half without loss of resolution, but I've never understood the missing digits thing. Both these "features" demand more presence of mind from the navigator than classic Ageton does. One good trick Umland missed was the boldfacing on column B that Ageton used. It helps the eye without making the table any bigger. Showing the integral minute values in red works as long as you've got color. But what if the tables are reproduced in black and white? I would have bracketed these entries with heavy horizontal lines top and bottom. Also, I'd have eliminated the vertical line separating A and B for the same angle. It's strange that each and every page has the formulas for A and B. By the way, Umland's not the first to publish the Ageton method tabulated to .2 minute. In Bowditch it says a math professor named Hickerson published such a table in 1944. However, his table was folded at 45 degrees, so his A and B columns periodically switch places. One of my buddies has a genuine HO 211. It's little. You can hold it in one hand while filling out your form. Bayless is small too. The main thing I dislike about HO 229 is that the books are so darn big. And EXPENSIVE -- the price has jumped way up. But for me 229 is quicker than 211 and there's less chance of a goof. I still like HO 211 though. Did the last Silicon Sea leg that way. -- paulhirose@earthlink.net (Paul Hirose)