Comparison

Sun Calendar vs Avalon Offshore

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

Head to head
About

Sun Calendar

Access detailed sunrise, sunset, and moon phase information with customizable calendars. Generate and share PDF or CSV reports, and track the sun's movement throughout the day. Offers thousands of predefined locations worldwide.

Highlights
  • Daily sunrise and sunset times
  • Moonrise, moonset, and moon phase data
  • Customizable multi-month calendars
  • Printable PDF and CSV reports
  • Location tracking and favorites
  • Map with distance measurement
Features
Currently charting
Read full description

For over 12 years we have been supplying Sunrise and Sunset calendars on our web site. We were awarded the Sky Award by the Griffith Observatory. We now have this app designed for the iPhone and iPad. All the features of the web site have been included plus more: • Daily times and other info is on the home screen • Sunrise, sunset, day length and solar noon times • Sunrise azimuth and sunset azimuth • Moonrise, moonset and moon phase times • Moon percent illuminated info • Easily create multiple month calendars • Print directly to your AirPrint printer • Email yourself the calendars, which are attached as PDFs. Print the PDFs from your laptop or desktop computer. • CSV data can be attached to the email • Copy an image of the current calendar into the clipboard • Various formatting options for times, latitude, longitude and larger font size selection • Choose the day of week you want the calendar to start on • Track Sun option will show local time on home screen and follow the sun across the screen during the day • Thousands of predefined locations, U.S., Canada and around the world • Favorites screen saves locations for quick selection • Ability to make a predefined location a favorite or add your own location as a favorite • Red Pin feature on the map makes it easy to measure distances between any two points

About

Avalon Offshore

This app provides advanced weather routing and navigation for sailors. It offers detailed weather forecasts from numerous models, collision alerts, and route optimization based on boat draft. Compatible with various nautical maps and augmented reality glasses.

Highlights
  • Advanced weather routing
  • NMEA 0183 and AIS integration
  • Collision alarm
  • Regatta start management
  • 65 automatic weather models
  • Bathymetric routing
  • Navionics Boating map compatibility
Features
Read full description

Avalon Offshore is a complete weather routing and navigation application . It works on iPads and iPhones. It also works on the new generation of Macbook Air and Pro,equipped with an ARM 64 chipset. Avalon Offshore integrated the whole set of functions that are useful to cruisers and offshore racers; weather routing, weather, navigation with NMEA 0183 and AIS collision alarm, anchoring alert, regatta start management wit laylines, etc… Avalon includes automatic loading of 65 weather models: NOAA GFS, Metro France Arpege,and Arome, DVD Icon, OpenWRF Skiron, etc Avalon also includes advanced functions such as: - Bathymetric weather routing, allowing calculation of routes taking into consideration the draft of the boat. - Simultaneous comparaison of routes across different weather models, different routes options, etc… - Free use of Avalon VPP to calculate customised VPP polars for single hull boats (main sail + genoa, code 0, gennaker, spinnaker, staysail and mizzen sail. - High compression of weather data on several models (GFS, Arpege, Icon, NAM Caraïbes et USA East) enabling to reduce by up to 95% volume of data, very efficient for satellite transmission (Iridium Go, Iridium Inmarsat, etc) - Easy weather routing module (from harbor to harbor) for a quick start of the app. - Compatible with ©Navionics Boating maps without additional cost. - Interfaced with ©Navily for a quick selection of the best moorings and harbors. - On time arrival : Calculate departure time to arrive on a given time - Compatible with ActiveLook® Augmented Reality glasses VPP Polars - Free use of Avalon VPP to customize your boat velocity preduction and adapt them to the exact caracteristics of your boat - Polar captation at sea Nautical Maps - Free raster nautical maps: NOAA, Linz, Brasil, New Zealand - In-app pack of maps derived from UKHO or SHOM covering France, UK Belgium, Portugal, Spain Carribean, Eastern and Western Mediterranean, Transatlantic, ... - Personal maps support: mbtiles, tif, kap, geotiff - Navionics maps: You can use your Navionics Boating maps with Avalon free of charge. Weather Sources - 65 automatic weather sources (wind, gust, current, wave and general weather) included in the Premium Option (in-app purchase) - Capability to load external grib files (as an alternative to the Premium option) - Capability to load external current grib from Tidetech® Includes one month free use of Premium options (see below) IN-APP PURCHASE: PREMIUM OPTION Includes: - Iridium data compression (reduce by 6 transmitted volumes) - additional weather sources: Arome, Arpege, NAM, CEP, Skiron .... - Weather data up to 394 hours including Wind, Gust, Waves, Precipitation, Storms, Cloud Coverage, Pressure, Temperature - Integration of currents in route calculation in covered areas (worldwide, Iberia Biscay and Ireland and Mediterranean sea) - Waves (Swell and wind waves) Privacy Policy and Terms of Use at: http://www.avalon-routing.com/new/privacy/ Warning: Continued use of GPS running in the background can dramatically decrease battery life. Policy and Terms of Use at: http://www.avalon-routing.com/new/privacy/

Screenshots

Sun Calendar4 screens
Avalon Offshore4 screens

Verdict

The call

The clearest difference is price: Sun Calendar at $2.99 against Avalon Offshore's $35.00. Sun Calendar also leads on in-app purchases (none vs 21) and chart position (#100 vs unranked). Avalon Offshore's advantage is update cadence (every 3 weeks vs every 5 months) and review sentiment (75% vs 63%). On ads and device support 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

Sun Calendar costs $2.99 and Avalon Offshore $35.00 up front. Avalon Offshore sells 21 in-app purchases, starting at $39.99 per year. Sun Calendar asks for nothing beyond the download.

UpkeepUpdate frequency

Sun Calendar ships an update every 5 months, Avalon Offshore every 3 weeks. The most recent releases landed on October 18, 2026 and October 8, 2026 respectively.

Scorecard7 real differences · 4 level
Sun Calendar versus Avalon Offshore: the parameters behind the verdict, then further details
ParameterSun CalendarAvalon Offshore
Price$2.99 — better$35.00
Rating4.3 (43 ratings) — better—
Positive reviews63.0% of reviews75.0% of reviews — better
Number of ratings43 — better—
Update frequencyEvery 5 monthsEvery 3 weeks — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
Best chart rank#100 — better—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS8.1 — better13.0
Further details — not scored
Size15 MB66 MB
Age rating4+4+
DeveloperSteven EdwardsAvalon Navigation Systems

Customer experience

Sun Calendar

All ratings43 ratings
Positive83.7%
Neutral0.0%
Negative16.3%
Written reviews27 reviews
Positive63.0%
Neutral3.7%
Negative33.3%

Avalon Offshore

Written reviews24 reviews
Positive75.0%
Neutral4.2%
Negative20.8%

In-app purchases

None

Sun Calendar

No in-app purchases

21 purchases

Avalon Offshore

Subscriptions1
  • Premium Subscription$39.991 Year
One-time20
  • England and Ireland South 2024$29.00
  • Portugal and Spain North 2024$29.00
  • East Mediterranean 2024$29.00
Show 17 more
  • Transatlantic Islands 2024$29.00
  • West Mediterranean 2024$29.00
  • Benelux and England East 2024$29.00
  • East Mediterranean 2023$39.00
  • Benelux and England East 2022$39.00
  • England and Ireland South 2023$39.00
  • Transatlantic Islands 2023$39.00
  • West Mediterranean 2023$39.00
  • Portugal and Spain North 2023$39.00
  • UK and Ireland 2024$39.00
  • UK and Ireland 2023$49.00
  • France Mediterranee 2023 SHOM$99.99
  • Lesser Antillas 2023$99.99
  • SHOM 2024 - France Med$99.99
  • Lesser Antillas 2024$99.99
  • SHOM 2024 - France Manche$99.99
  • SHOM 2024 - France Atlantique$99.99

Questions

Is Sun Calendar free?
Sun Calendar costs $2.99, with no in-app purchases.
Is Avalon Offshore free?
Avalon Offshore costs $35.00, and also offers in-app purchases.
Do Sun Calendar or Avalon Offshore have ads?
Neither Sun Calendar nor Avalon Offshore shows ads.
Which is updated more often, Sun Calendar or Avalon Offshore?
Sun Calendar ships an update every 5 months, and Avalon Offshore every 3 weeks. Most recently, Sun Calendar was updated on October 18, 2026 and Avalon Offshore on October 8, 2026.

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