NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
HO 211 vs. Bayless
From: Paul Hirose
Date: 1999 Jul 04, 12:08 EDT
From: Paul Hirose
Date: 1999 Jul 04, 12:08 EDT
Joe Shields mentioned the version of HO 211 by Bayless. I bought that book, but still prefer the table in Bowditch Vol 2 (which I assume is identical to the original HO 211), at least at a desk at home. The main advantage is the consistent arrangement of the A and B columns. HO 211 always puts B in the right-hand column. Also, the numbers in the B column are boldface, at least in the Bowditch reprint. Bayless is less Murphy-resistant. B can be in either column; you have to look at the heading. It's clearly marked, but you do need to keep your wits about you, more so than with Ageton. HO 211 is able to keep the A and B columns always in the same places because it goes out to 90 degrees on the top column headings before "turning around". However, the behavior of trig functions is such that the first and second halves of the table are mirror images. E.g., A of 10 deg = B of 80 deg. Bayless takes advantage of this by only going to 45 degrees before turning around. It cuts half the size off the table, but also forces A and B columns to swap places. I'm sure Ageton was aware of the redundancy in his table, but accepted it in the interest of reliability. After all, it only costs 18 more pages. Another complaint is that Bayless likes to omit leading digits, if they're identical for several entries in a row: Ageton Bayless 163322 163322 162738 2738 162250 2250 Perhaps I just have a mental block, but the Bayless format is slower for me to absorb. One practical matter is that Bowditch vol. 2 is a large book and lies open to any page in the table. Bayless is a small paperback and tends to flip closed if you let go of it. (However, a 1940s-vintage HO 211 for air navigation owned by a friend has the same problem.) For negative altitudes, the rules in Bayless are incorrect. I must say there are some good points to Bayless. Tabulating only whole minutes simplifies the Bayless table. Each column contains one complete degree. On the other hand, Ageton only covers a half degree per column, since 120 entries won't fit. If you want to look up, say, 16 deg 48 min, find the 18' row in the 16 deg 30' column. Not hard, but I've managed to botch it. The Bayless table has a clean, uncluttered look compared with the many unneccessary dividing lines in Bowditch. Neither table does a good job indicating the left-hand minutes column goes with the top column headings and vice versa on the bottom, though. Bayless does include a method, devised by guru D.H. Sadler (of the Royal Observatory, I believe) for solving sights when LHA is near 90 or 270. HO 211 becomes very inaccurate in such circumstances. The Bayless table only has 1/4 the number of pages as HO 211. Mike Pepperday's S-Table is yet another Ageton variant. Like Bayless, he eliminates redundancy by turning the table around at 45 degrees. His main improvement is to number the table all the way to 360 degrees. You can enter his table with LHA directly, instead of having to convert to meridian angle if LHA is more than 180. Additional hand-written column headings would let you do this with the other HO 211 variants, of course.