CelestNav™ Frequently Asked Questions

Where can I learn more about celestial navigation?

Your local yacht club or US Power Squadron is a good place to start. A class from someone who knows how really sets you up well.

The best source of online information is http://www.celestialnavigation.net; it has information on theory, practice, instruments, history, and astronomy.

I also recommend Dan Hogan's email list devoted to traditional navigation. It features a periodic navigation problem, which members work on privately and then discuss on the list--great for keeping the rust chipped off your celestial skills. Subscription instructions, list archives, nav problem archives, a celestial tutorial, and other navigation links are at http://www.wa6pby.com/.

What dates does CelestNav's nautical almanac cover?

The nautical almanac is valid for all dates that your Palm-powered handheld can represent. That means it's valid for years 1904-2031.

What bodies are included?

CelestNav can use the Sun, the Moon, the 57 standard navigational stars (plus Polaris, for a total of 58), Venus, Mars, Jupiter, and Saturn.

What Palm-powered handheld should I buy?

CelestNav runs on any Palm-powered handheld built since 1998 (Palm III or newer), using any available version of the operating system. If you're buying a PDA specifically for navigation, though, there are some additional considerations. You probably want removable/replaceable batteries so that you don't have to depend on a charger. And you should have some sort of backup capability in case your batteries go flat, so that you can carry an extra copy of CelestNav on the backup media.

Unfortunately, as of June 1, 2003, no currently produced pocket-sized PalmOS device meets these specs. You need to figure out how you're going to recharge your PDA at sea, either using ship's power (what if it fails?) or an external battery pack (see the following section).

I had been recommending the Palm m125 as the cheapest device meeting these criteria, and the HandEra 330 as the nicest and most powerful. The HandEra 330 also gave you the choice of replaceable AAA batteries or a rechargeable battery pack. Both of these excellent devices have been discontinued by their respective manufacturers. The Sony Clie SL10 also fits my specs, but it too has been dropped. If you can find any of these used or remaindered, they would be good choices, as would those of the venerable Handspring Visors which take AAA batteries.

The AlphaSmart Dana is the only current production PalmOS device that I know of which combines field-replaceable batteries and removable storage cards. It's much larger than the typical PDA, which could be good or bad, depending on your perspective. With its built-in keyboard, it could be quite handy on a boat. It is, after all, designed as a laptop replacement, and many of us would feel much more comfortable taking a $400 gadget to sea instead of our expensive laptops.

There are two unreleased devices on the horizon that promise to be good choices for navigators, once they are shipped. The Garmin iQue 3600, with its built-in GPS and ARM processor, would be an obvious choice for a navigator. Think about how you'll recharge it in an emergency, though, and think also about the wisdom of having two backup navigation methods housed in one single fallible piece of electronics--the iQue 3600 is not weatherproof. The Aceeca Meazura is waterproof ("drop it in a bucket of water", the company president told me) and hardened, but has no removable storage, requires a battery charger, and is bulkier and heavier than a typical PDA.

If you buy a color screen PDA, be sure to try the unit outside in bright sunlight. Some models are essentially unreadable in bright sun.

CelestNav will run on current-production hardware manufactured by any of the PalmOS licensees: Palm, Sony, AlphaSmart, Aceeca, Garmin, Acer, HandEra, Handspring, Kyocera, Samsung, Symbol, Fossil. For a current list of hardware, with prices and web links, see PalmSource's list of Palm-powered products.

If anyone ever actually uses CelestNav on a Fossil Watch PDA, with sextant, at sea, please send a photo!

What addons are most useful?

The most useful accessory is a plastic bag. It's a very low-tech way to protect your PDA when you go out on deck. CelestNav's sight entry screens are designed so that you don't need your stylus to take sights--just your fingers will do fine. Setup, planning, and fix computation do need the stylus.

One solution to the rechargeable-only trend of manufacturers is an external charger that uses AA or AAA batteries to charge your PDA. You can find these at http://www.hslight.com/products/ and http://www.wholesale-pda-accessories.com/BC .html. I've heard rumors that that Garmin iQue 3600 will have a similar accessory available. Disclaimer: I've seen these in catalogs, but have never used one.

Software that belongs on every navigator's PDA includes Big Clock (especially handy for setting the PDA's clock time to the nearest second); BackupBuddyVFS for self-contained backups of your PDA to expansion cards; and TideTool, for tide and current predictions.

Dale DePriest maintains comprehensive lists of navigation resources for PalmOS: one for general navigation software, GPS software and one for hardware including cases.

Does CelestNav run on the new ARM-powered handhelds running PalmOS version 5?

Yes, it runs quite well. CelestNav does not yet, however, take best advantage of the ARM's speed for numerical computations. This upgrade is on the to-do list, though.

What sextant should I buy?

I've tried the plastic sextants and must reluctantly recommend against them. There's too much variability in observations: if you're standing perfectly still in your backyard and taking observations of a nearby flagpole you're not likely to get the same reading twice in a row. They're good enough to get you to your landfall, but will be very frustrating for a beginner to learn on.

I personally carry an Astra IIIB, which you can purchase from Celestaire. And Seattle's own Captain's Nautical Supplies always seems to have a nice assortment of vintage brass sextants on consignment whenever I go in there.

What happens if I lose my password or buy a new handheld?

If you buy a new handheld, simply perform two Hotsync operations, one with the old one and one with the new one. When you Hotsync the new device, your desktop computer will recognize that it's new, ask for your username, and then download all of your information from the desktop to the new PDA. Your CelestNav data, program, and password will be transferred to the new PDA. Just start using the new handheld.

Before you toss your old PDA, make sure that all of your infomration made the trip to the new one. Some programs, either by design or by accident, don't make backup copies of all databases. Ebooks and mapping programs often behave this way.

If you lose your password, send an email to support@mobilegeographics.com with your name and Hotsync ID. We'll send you a reminder of your password.


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