Comparison

qtVlm vs EZ Celestial Navigation

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

qtVlm

This navigation software is designed for sailing boats, offering a free version with basic GRIB viewing and an optional full version with advanced weather routing, chart modules, and communication features. It supports various chart formats and NMEA data sources, with a simulation mode for learning.

Highlights
  • GRIB viewer with advanced functions
  • Weather routing and route modules
  • Support for Raster, Vector, and MBTiles charts
  • Harmonic file support for tides and currents
  • AIS and Iridium GO! communication
  • Anchor Alarm module
  • Simulation Mode for learning
Features
Read full description

qtVlm is a navigation software for Sailing Boats. The application has a free version with basic features and a full version available through in-app purchase. The free version of qtVlm is a full grib viewer displaying all types of gribs and providing many advanced grib functions. It supports basics charts and some simple instruments. It includes also an Anchor Alarm module, a viewer for shapefiles, for instance those coming from SHOM, and can be configured to receive boat position either from internal GPS or from an external NMEA source connected through tcp, udp or gpsd. The full version adds many functions and features: - Weather routing and route modules, - A complete set of navigation Instruments, - Charts modules for Raster charts, Vector charts (S57, S63 and CM93) and mbtiles, - Support for Harmonic files (tides and currents), - Iridium GO! communication - AIS, - Start line mode, - Access to Great Circle gribs, qtVlm can also be used in Simulation Mode, which allows you to simulate a navigation through our server. This is the best way to learn using qtVlm. Once activated the full version will be available on all your iOS devices.

About

EZ Celestial Navigation

This app simplifies celestial navigation using a sextant, providing tools to calculate your position at sea. It offers automated calculations or manual table access, with features for observation archiving and compass checks. Ideal for learning and practicing traditional navigation methods.

Highlights
  • Automated sight reduction and LOP plotting
  • Manual Nautical Almanac and Pub. 229 table access
  • Observation archiving and restoration
  • Compass check functionality
  • Printable Nautical Almanac pages and reports
  • Universal app for iOS and macOS
Features
Currently charting
Read full description

Celestial navigation has never been easier! With ezAlmanacOne and a sextant you will be finding your fix like a pro in no time! ezAlmanacOne is an evolution of the iPad version of ezAlmanac with the modern user interface used in the Windows 10 version of ezAlmanac. All of the features of ezAlmanac plus new features including: - Universal app runs on iPad, iPhone, iPod touch, and the new MacBook with M1 processor. - Supports all device orientations. All screens support zoom and pan. - Make bearing observations to perform compass checks. - Archive saved observations and restore observation data from an archive. - Includes quick start guide, usage examples, and other documentation to learn celestial navigation. - Print/Output Nautical Almanac pages, observation reports, and other app documentation. ezAlmanacOne will help you perform celestial navigation exactly as it has been done for hundreds of years. It produces all Nautical Almanac (1960-2059) and Pub. 229 tables exactly as you are used to seeing them in the printed form. All tables can be accessed directly for manual usage if you choose to do so. Since they are produced by the software they support zooming and panning, and you can highlight in the tables to easily find the correct value to use. Most users, however, will prefer to let ezAlmanacOne do all of the work. Simply enter the basic sight parameters, make and enter your observations, and ezAlmanacOne will do the rest. It performs all of the steps to correct your observation, find GP of the object, do the sight reduction, and plot the LOP. No steps are skipped and all details are shown. Click where the LOPs cross in the plot and you have found your fix! Besides finding your fix, ezAlmanacOne is one of the best tools available to perform compass checks from a bearing observation of one of the navigational bodies. The compass check function supports checking up to 5 devices from a single bearing observation. ezAlmanacOne will also create a report of your compass check that can be saved as a PDF file or printed for the ships records. Celestial navigation instructors love ezAlmanacOne because it does celestial navigation exactly as they teach it. Values obtained from the Nautical Almanac and Pub. 229 are clearly identified with an icon of the book. When you press the book icon you are taken to the page that has that value with the row, column and value highlighted. Even when ezAlmanacOne is doing all the work, it can teach you how to do it manually using the books. For manual celestial navigation you can generate and print Nautical Almanac pages to use as a backup on a passage. You can even print the sight reduction forms and plotting sheets you will need. ezAlmanacOne performs all astronomical calculations using the NOVAS 3.1 software from the US Naval Observatory (USNO) and a JPL ephemeris that covers the years 1960 through 2059. It also implements WMM-2020, the latest World Magnetic Model software available from NOAA, to compute magnetic declination. Since all calculations are performed in the software, ezAlmanacOne is fully functional with no dependency on the internet.

Screenshots

qtVlm4 screens
EZ Celestial Navigation4 screens

Verdict

The call

The clearest difference is price: qtVlm at Free against EZ Celestial Navigation's $29.99. qtVlm also leads on update cadence (weekly vs monthly). EZ Celestial Navigation's advantage is rating (4.9 vs 3.7) and in-app purchases (none vs 1). On ratings volume, ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

qtVlm is free to download; EZ Celestial Navigation costs $29.99 up front. qtVlm sells 1 one-off in-app purchase. EZ Celestial Navigation asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

EZ Celestial Navigation holds the better App Store score, 4.9 against 3.7. Both are backed by a comparable volume of ratings — 9 and 26 respectively. Written reviews point the same way: 79% of qtVlm's written reviews are positive against 100% of EZ Celestial Navigation's.

UpkeepUpdate frequency

qtVlm ships an update weekly, EZ Celestial Navigation monthly. The most recent releases landed on October 22, 2026 and October 20, 2026 respectively.

Scorecard7 real differences · 4 level
qtVlm versus EZ Celestial Navigation: the parameters behind the verdict, then further details
ParameterqtVlmEZ Celestial Navigation
PriceFree — better$29.99
Rating3.7 (9 ratings)4.9 (26 ratings) — better
Positive reviews79.2% of reviews100.0% of reviews — better
Number of ratings926 — better
Update frequencyWeekly — betterMonthly
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
Best chart rank—#138 — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better13.0
Further details — not scored
Size100 MB153 MB
Age rating4+4+
DeveloperMeltemus SASEZ Celestial LLC

Customer experience

qtVlm

All ratings8 ratings
Positive62.5%
Neutral0.0%
Negative37.5%
Written reviews24 reviews
Positive79.2%
Neutral8.3%
Negative12.5%

EZ Celestial Navigation

All ratings26 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews4 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

1 purchases

qtVlm

One-time1
  • Full version$49.99
None

EZ Celestial Navigation

No in-app purchases

Questions

Is qtVlm free?
qtVlm is free to download, with in-app purchases available.
Is EZ Celestial Navigation free?
EZ Celestial Navigation costs $29.99, with no in-app purchases.
Which has better reviews, qtVlm or EZ Celestial Navigation?
EZ Celestial Navigation is rated higher. qtVlm averages 3.7 out of 5 from 9 ratings, while EZ Celestial Navigation averages 4.9 from 26 ratings.
Do qtVlm or EZ Celestial Navigation have ads?
Neither qtVlm nor EZ Celestial Navigation shows ads.
Which is updated more often, qtVlm or EZ Celestial Navigation?
qtVlm ships an update weekly, and EZ Celestial Navigation monthly. Most recently, qtVlm was updated on October 22, 2026 and EZ Celestial Navigation on October 20, 2026.

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