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    Re: Rude star finder
    From: Sean C
    Date: 2015 Dec 15, 18:16 -0800

    Frank,

    You wrote:

    ...it doesn't much resemble the awful Rude star finder (also known as the HO 2102-D star finder) --except to the extent that the Rude star finder was also a development of a common planisphere. Would anyone care to make a list of all the features that make this Japanese star finder (assuming that's what it is) superior to the Rude star finder, so beloved by USN-worshipping navigation enthusiasts? Does it share any features with the Rude star finder that are not found on a common planisphere?

    ...and, in another post:

    I'll [...] say that the Rude star finder (or H.O. 2102-*) is a miserable beast. It's nothing more than a mediocre planisphere with altitude-azimuth grids attached. There are better ones available for a few bucks including the very nice design created by David Chandler and sold as "The Night Sky" which Bill has already mentioned. And it's easy today to print your own alt-azm grids and add them to one of those cheap planispheres if you really like the scales. Of course, many navigators develop attachments to this rude device, this "ugly duckling", hoping one day it will become Cygnus the Swan (a constellation that a cheap planisphere will display as a recognizable cross shape lying along the Milky Way, but the Rude star finder shows only as a single dot). I suspect that a lot of this has to do with the visceral pleasure of learning the stars for the first time. No matter how you do it, whatever device or system you use to learn the stars and constellations for the first time, it will always occupy a warm spot in the observer's heart. 
    [...] The one really big exception to this reality --and one that mattered a great deal in the period when the star finder was in practical use-- is when a navigator is dumped aboard a vessel with no preparation possibly thousands of miles from home, maybe under southern hemisphere stars when he has only previously seen northern hemisphere stars.
    If you like historical re-creationism, and if your favorite era is the middle 20th century, then the star finder is a tool appropriate to your re-creationist endeavors. Go for it! But if you're a modern navigator, there's little excuse for using it, except, of course, that natural affection I mentioned above. There are vastly better software apps for every class of device, and if you're afraid of running out of power, there are common analog planispheres widely available. Better yet, learn the stars before you sail. You'll have more fun. And don't recommend this goddamn Rude beast to a novice navigator or a beginning navigation enthusiast --unless you're a sadist.
    I must say, I just don't understand your apparent hatred of this device. I can't list the features which make the Japanese version better than the Rude, but I can list a few that make the Rude better (for a navigtor, IMHO, anyway) than most "common" planispheres:
    • The Rude can easily be set up for practically any latitude, north or south. Most others are limited to a range of about 20 degrees in one hemisphere.
    • It shows only those stars in which the [nautical] navigator would primarily be interested; i.e. those which would be visible at twilight, when sights would be taken. Less clutter makes it easier to get the information you're after, and make it easier to read in low light conditions.
    • Stars and text are printed in black on a white background, which also aids in low light readability.
    • The included overlays have altitude/azimuth lines which extend across the entire visible area of the sky, reducing ambiguity and allowing for pre-setting of the sextant. There's no need to print one's own overlays, requiring special, transparent printer media and some way of accurately producing the somewhat complex diagrams. Most other planispheres only indicate declination & RA, requiring further calculation to get an approximate Hc/Zn.
    • The current positions of the sun, moon & planets (or any other celestial body, for that matter) can easily be plotted directly on the face of the Rude using a pencil & the included plotting overlay...and just as easily erased.
    • At about 8.5 inches across, the Rude is more compact than some other planispheres. (But still larger than others.)

    In fact, the only drawback I can think of is that an almanac is also required to set it up. But, this is something the navigator should have on hand, anyway. Besides, it's not as if LHA Aries is at all difficult to work out with an almanac. And once you have that, you can have a list of visible bodies with approximate Hc & Zn in literally seconds...for any location on Earth.

    You mentioned that the only time the Rude was really useful was in the case of the navigator in the middle of the ocean, under an unfamiliar sky and not being prepared. Of course, the prudent navigator should have been cross-checking his GPS position with celestial the whole time. But is that often the case? Having never been a sailor, I really don't know. I can only imagine that many sailors, much like "our man" in "All is Lost", would be woefully unprepared for a stuation involving the loss of GPS and other modern position-fixing technologies. In such a case as this, wouldn't the Rude be a welcome, useful and comforting addition to a backup kit?

    Don't get me wrong: I love my "Firefly" planisphere. I think it's very useful...for the amateur astronomer or casual sky-gazer. But, for the navigator, I find the tailor-made Rude to be better suited to the task of planning for twilight sextant sights.

    Just my two cents. ;)

    Respectfully,

    Sean C.

       
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