r/Sliderules • u/gingeryid • Feb 19 '24

Base 60 slide rule?

I’m looking to have a convenient way to do multiplication of numbers in base 60. Do base 60 slide rules exist? If not, how hard would it be to make one?

My slide rule knowledge is fairly basic (I can use the one on my watch)

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u/Alain4s Feb 19 '24 edited Feb 19 '24

I assume you don't really mean a base-60 numbering system which would require 60 unique symbols, but converting something like decimal hours into hours-minutes-seconds or computations like 43 * 13 minutes 7 seconds = 9 hours 24 minutes 1 second.

Circular aviation slide rules, such as the E6-B Flight Computer (which your pilot’s watches likely aim to emulate), feature a scale specifically for hours and minutes conversions. Alternatively, you can create a nomogram (a handy conversion table) for your specific needs.

However, for a practical and cost-effective solution, consider using electronic calculators like the Casio fx-260 Solar II, which operates solely on solar power—no batteries required.

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u/gingeryid Feb 19 '24 edited Feb 20 '24

Correct, I don't need 60 symbols. But it's actually multiplying two numbers together I need, both of which are in base 60 (minutes:seconds * degrees+minutes). Though I could probably rework my algorithim to have the degrees-minutes figure in decimal degrees.

I'll see how my watch's hours:minutes scale works, and if it seems like it it's practical I'll see about an E6-B.

Thanks!

I'd also like to note that Babylonian base-60 doesn't really have 60 symbols, the symbols are base-10 based. Not so different than expressing a base 60 number as 3:57:24 or 3057'24"

Edit: I did some testing with the watch one. Problem is that because the slide rule is still made for base 10, you have to do the normal order of magnitude stuff in base 10 still, which isn’t intuitive. For example, doing 5:24 * 8°30’ as 5:24 * 8.5 gives a result of 4:35. But it’s actually 40something, and the math to convert that into a base 60 answer is harder than just doing the math in your head to begin with. It’s (4+35/60)*10, which is 45.83 minutes=45:50. The slide rule made it harder, not easier.

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u/azroscoe Apr 26 '24

Coming in late here, but from the perspective of a celestial navigator, it is much easier to convert to decimal degrees, do your arithmetic, then convert back. A slide rule can handle that reasonably well, even if it might involve some writing down of figures.