Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: The ultimate navigation watch?
    From: Gary LaPook
    Date: 2013 Aug 12, 21:54 -0700
    You might like this old post:



    From: Paul Dolkas <paul@dolkas.net>
    To: garylapook@pacbell.net
    Sent: Monday, August 12, 2013 9:25 PM
    Subject: [NavList] Re: The ultimate navigation watch?

    Actually, I can use the E6-B, although I’ll admit I had to look at a few brands before I found one with big enough numbers. And it does get used for the really important stuff, like, well,  figuring tips and gas mileage. Seriously though, I think the real value is that it gets used often enough to remind oneself how it works, so that you don’t make mistakes when you need to use a real one.
    As for your sidereal watch,  a few years ago I was doing a design project for grad school that involved looking at different types of watches. There’s one the astronauts are fond of called the Timex Datalink. It’s got a small LCD screen and a processor that can be programmed to do different things. There’s also a small community of programmer types that write “wrist apps” for the fun of it. I’m sure programming it to display sidereal time, (or Mars time, or whatever) wouldn’t be too difficult for one of these guys.
    As for piloting my Ryan across the Atlantic, A-12 in hand, steely glint in my eyes….
    Paul Dolkas
    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Gary LaPook
    Sent: Monday, August 12, 2013 7:44 PM
    To: paul{at}dolkas.net
    Subject: [NavList] Re: The ultimate navigation watch?

    You must be younger than me if you can read the E-6b scales on a watch bezel. Sure, it tells the world that you are a pilot but can you really use those scales?

    I always wanted a digital watch that could be adjusted to keep sidereal time so that I could dispense with the almanac for star shots, know where I can one like that?

    What are you fling across the ocean? Using your A-12 on those flights?

    See my website:


    From: Tom Sult <tsult{at}mac.com>
    To: garylapook{at}pacbell.net
    Sent: Monday, August 12, 2013 7:14 PM
    Subject: [NavList] Re: The ultimate navigation watch?

    That is fantastic. Given that the E6B on the watch requires an electron microscope to read, I would say this is a vast improvement to the functionality of the watch and great fun to design and have made. 

    Tom Sult
    Sent from my iPhone

    On Aug 12, 2013, at 20:53, Paul Dolkas <paul{at}dolkas.net> wrote:

    I’ve been working on a project the last few years to come up with the ultimate navigation watch.  When I first got interested in celestial navigation, I used my old battered digital watch to time my sextant shots, and it rapidly became clear that I needed to do better. So I started looking around, and came up with my list of what the perfect CN watch would be like:
    1.       First off, it would have to be quartz. Although I truly love mechanical watches as an art form (I’m an engineer), let’s be practical: even a cheap quartz watch blows the doors off of even a very expensive mechanical one.
    2.       It would have to be a chronograph – i.e. you need to see the watch function AND the stopwatch at the same time.
    3.       The stopwatch should have a lap timer, so that you can freeze the time when you take a shot.
    4.       It should also have a timer, since I own a bubble sextant (A-12) and need to time the two minute interval when averaging shots.
    5.       It wouldn’t hurt to be one of those radio synchronization watches that resets itself every now & again with an atomic clock.
    6.       It also wouldn’t hurt to be somewhat analog (i.e. hands) since, let’s face it, digital watches look geeky, and this watch has to look cool.
    Now, there are a whole bunch of watches that fit this description. But since my primary interest is in aviation navigation, it also had to be a pilot’s watch. For those unfamiliar with a (real) pilot’s watch, they are usually chronographs, and have a rotating bezel, similar to a diver’s watch. But instead of being used for timing one’s duration underwater, these bezels are actually small circular slide rules, and are used to do time-distance problems so you can figure out where you are. Airplanes, as a rule, don’t come equipped with odometers.
    This narrows the field considerably. In fact, the only pilot’s watch that also synchronizes is a Citizen Atomic Navihawk. Fortunately, they aren’t exorbitantly expensive. They run about $600 new; mine was about half that used on E-Bay. All in all, a pretty nice looking watch:
    But it’s still missing something. After playing around with it for a few months, I came up with the idea of a countdown bezel. Unlike a diver’s timing bezel, which lets you know how long you have been doing something, a countdown bezel is just the opposite: it has the minute numbers running counterclockwise. So if you want to know when your next landmark is coming up (or, more commonly, when the pasta is ready), you set the number of minutes you want opposite the minute hand, and the zero mark is when that time is up. Simple.
    The next problem was how to make one. Fortunately, 3D printer technology has come a long way, and you can design your own gizmo, E-mail it in to a shop, and Viola! A few days (or weeks, depending on the material) later, your dreamchild arrives in the mail. So I designed a little plastic ring that snapped onto the outer bezel, and it looked like this:
    IMG_1498I had a lot of fun using it for about a year.
    And then somebody on NavList had to go and spoil my fun by posting an article about the Lindberg Longitude watch.
    For those that missed it, back in the 1930’s Charles Lindberg designed a watch with a bezel that would convert your local noon time (in UTC) into your longitude. Really clever bit of design, this, and gorgeous to boot ( http://www.watchtime.at/archive/wt_2006_06/WT_2006_06_104.pdf). Needles to say, I was green with envy.
    For fun (and not wanting to spend over $4000 on a watch), I decided that I would make a second bezel, somehow incorporating at least some of the Lindberg functionality. It took a few design iterations to get something that was simple enough to fit on a small bezel. In order to do so, I had to make some basic decisions: the Lindberg watch converted hours, minutes and seconds into longitude: I on the other hand would only worry about the minutes. I figured you usually know what time zone you’re in, so there’s no need to worry about the hours. And I usually can’t figure local noon to better than the nearest minute anyway using a bubble sextant, so I’m not going to need to worry about the seconds. The result looks like this:
                                                                                                                                                   &nb sp;&nb sp; 
    This one is made of metal (silver); cost me about $50, and after infilling the markings & adding  a luminescent dot at 12, looks like this installed on the watch.
    When you look at it from the top, it looks and works like a countdown bezel. But the blue markings around the side can be used like the Lindberg watch.
    To use it, you first take a noon shot to figure the time of your local noon.   You then compute your longitude in two steps - the first using the hours, and next using the minutes.  The hours you work out on paper. For example in PST time zone, noon is 20:00 UTC, which works out to be 120o west longitude. You then work the minutes by first rotating the bezel to the left or right by the number of minutes given by the Equation of Time. Lastly, you can read on the side of the bezel the number of additional degrees longitude indicated by the minute hand.  Each minute past one of the blue markings on the face is 15 arcmin. So in the last photo of the watch, for example, the equation of time offset is 6 minutes late (-), and the minute hand is one mark beyond 2 additional degrees. So the location in longitude would be 120o + 2o + 15 arcmin = 122o, 15’.  You could of course get the same answer working it all out on paper; but like the Lindberg watch, this saves a bit of calculating. Usually, I find myself using it in reverse: I want to work out when local noon will be for my assumed longitude, so I know when to take the noon shot.
    It’s a pretty fun watch, if I don’t say so myself. Not that I often need to calculate longitude while piloting solo across the Atlantic, but it’s kinda nice knowing that I could.
    -Paul Dolkas
    View and reply to this message: http://fer3.com/arc/m2.aspx?i=124847
    View and reply to this message: http://fer3.com/arc/m2.aspx?i=124850
    View and reply to this message: http://fer3.com/arc/m2.aspx?i=124851
    View and reply to this message: http://fer3.com/arc/m2.aspx?i=124854

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site