NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Hanno Ix
Date: 2015 Jan 17, 16:31 -0800
Attached are pictures of a 4-page brochure where I put into one package all the components you need to do sight reduction by hand. It contains a worksheet, the hav-table for the hav-DONIOL method and the azimuth diagram. The pages are laminated and bound so they will withstand some rough work on the water. You can treat the lamination such that it accepts repeated writing with pencil and erasing. More on that later.
There will be always navigators who prefer their computers, calculators, tables or slide rules of the straight, circular or tubular kind. Nothing wrong with that. This brochure is meant for those who want, or need, to use the barest possible means without sacrificing accuracy. It is also is the cheapest tool for the purpose I can think of. And its mechanics will never break since there aren't any.
The process on the worksheet is easy to follow. It contains a simple scheme for the one multiplication that occurs in the hav-DONIOL formula delivering directly - and only - the needed four leading digits of the result in short order. Virtually all the tools I mentioned above were invented to do sight reduction without having to execute the dreaded and error-pronelonghand multiplications. This scheme here will, I think, keep the pain at a very acceptable level and it is easy to check. You still can use your calculator if you prefer. It takes about 7 minutes to complete the calculations.
As to the lamination: standard lamination does not accept pencil marks but will after you roughened it up slightly with a very fine sandpaper. But neither the eraser at the end of a standard pencil nor water will erase properly, however the white "Steadtler" type will do very well. I hear a product of www.oregonlam.com will accept pencil marks that are easly erasable, too. I haven't tried it yet.
I gave the brochure the name MHR-2015 since it is a modern-day self contained tool for sight reduction just as the MHR's were. It performs as well, takes less space and it is much, much simpler to build. Try it !
H
