A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Saffo
Date: 2015 Feb 3, 10:45 -0800
- First of all, when it comes to bubble horizons, I always defer to you, Robert! (For everyone else, I am serious -- Robert knows more about Plath AFs than anyone I know and I would always ask him first if I had AH questions). Here are my thoughts:
- The ideal AF has a dimmable light source, an adjustable bubble and a well-designed reticle. Dimmable matters bec one needs diff light levels for day/dusk/night sights. Adjustable matters bec of diameter of target. A well-designed reticle (I like concentric circles w/crosshairs) will help compensate if the bubble is not adjustable.
- I believe that the early Plath "Firefly" AH is thus the best option bec it has both an adjustable bubble and dimmable light source. Regrettably I have never been able to get my hands on one, so hope others with experience will add their comments.
- the next generation Plath AH has a dimmable light source that draws power from the sextant's batteries, but no bubble adjustment. Its reticle is a simple crosshair. Its performance is acceptable, but I miss having an adjustable bubble esp as the reticle leaves much to be desired.
- the third gen Plath AH has a non-dimmable (red LED) light source powered by internal batteries. Bubble is not adjustable. Reticle is an octothorpe pattern. This seems to be the worst of all options. I'd love to get rid of it but cannot in good conscience sell it to anyone because its performance leaves so much to be desired.
- The C&P AH has a dimmable light source powered off the sextant, but no adjustable bubble. Its reticle is cut so that it is much easier to determine the bubble center than on the two Plath AHs I have. I thus find it a satisfactory AH, but expect that a Firefly would be superior.
- The modified A10 is a really terrific option as it has both dimmable light and adjustable bubble. And if one is lucky, they can be had for considerably less than a Plath or C&P. Mine was modified by Bill Morris, so am hoping he will step in and talk about his experience as this is a really nifty option if one can get an A10 capsule
Finally, a qualification about my experience. All of my use has been in a backyard or from the shore. I cannot imagine using an AH on the water on anything smaller than an aircraft carrier. AHs are fussy, sensitive accessories and hard enough to use when one is comfortably set up with a table and a cup of tea on terra firma. Using them while bobbing among the waves strikes me as being like trying to thread a needle while giggling...