Comparison

Nautical Calculator Preview vs Navigation Almanac

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

Head to head
About

Nautical Calculator Preview

This app provides comprehensive tools for marine navigation, including real-time ship movement, route planning, and advanced sailing calculations. It also offers features for collision avoidance, maneuvering, and learning maritime regulations and signaling.

Highlights
  • Real-time ship movement
  • Route planning
  • Mercator and Great Circle sailing
  • Collision avoidance
  • Maneuvering calculations
  • COLREGs and maritime signaling
  • Offline GPS
Features
Read full description

The application to assist in solving the most important marine problems. - For Marine Navigation +Real-Time Ship Movement; +Route Plan; + Mercator Sailing. + Greate Circle Sailing. + Meridional parts. + Plane Sailing. + Traverse Sailing. + Wheel over. + Current and wind sailing. + Allowing for current and wind. + Calculate true wind and apparent wind on a ship running. + Nautical Almanac + Two Lop Fix + Three Lop Fix + Correcting marine sextant altitude of sun and stars. + Probability Distribution Function. + Standard Deviation and Error. + Offline GPS. - For Maneuvering : -Avoid collisions -Change of station in cases: + with time specified + with speed specified + with course specified + Course and speed of another ship. + Closest point of approach(CPA). + Ability to reach another ship going faster. + Close or open to another ship in cases : - as quickly as possible. - on a constant bearing. - with time specified. + Maneuver to intercept a target ship going faster. + Maneuver to intercept ahead a target ship. + Close to another ship as close as possible. +Keep watch for a target ship within a range of distances; +Maneuvering with added calculating of turning. +Bearing and distance to another ship in advance. - For Learning : +International regulations for preventing collisions at sea (COLREG) include Rules; Lights signs; Shapes signs and Sounds signs. + Marine signalizations include Flag signaling; Morse signaling by hand; Morse code. + Maritime buoyage system. + Unit Conversion for Maritime. + Glossary of Marine Navigation. +Maritime Theory. +Global Lighthouses System. author Vu Cong The. vucongthe@gmail.com - Các tính toán hàng hải và vận động tàu, bao gồm : +Dịch chuyển của tàu theo thời gian thật; +Lập kế hoạch hành trình; +Hành trình theo hải đồ Mercator +Hành trình theo cung vòng lớn. +Vĩ độ tiến +Dự tính vị trí tàu một hướng và nhiều hướng. +Tính và đè độ dạt gió dòng. +Tính toán lượn vòng của tàu. +Tính toán gió thực và gió biểu kiến trên tàu đang hành trình. +Lịch thiên văn hàng hải. +Phương pháp hai đường vị trí. +Hiệu chỉnh độ cao mặt trời và sao đo bằng sextant hàng hải. +Tính hàm phân phối xác suất. +Tính sai số chuẩn và độ lệch chuẩn. +Hướng đi, vận tốc của tàu mục tiêu. +Tránh va. +Các thông số ở điểm tiếp cận CPA. +Các thông số trận địa với thời gian hoặc khoảng cách cho trước. + Xác định khả năng tiếp cận tàu mục tiêu có vận tốc lớn hơn. +Thay đổi khoảng cách tới một tàu khác với : - Thời gian ngắn nhất. - Thời gian cho trước. - Phương vị không đổi. +Vận động cắt mũi hoặc lái một tàu mục tiêu có vận tốc lớn hơn. +Vận động cắt mũi một tàu mục tiêu. +Tiếp cận một tàu khác ở cự ly ngắn nhất. +Tính các yếu tố trận địa với thời gian hoặc cự ly cho trước. +Thay đổi trận địa trong các trường hợp: -với thời gian cho trước. -với vận tốc cho trước. -với hướng đi cho trước. +Vận động trong dải khoảng cách. +Tính toán lượn vòng trong vận động. -Tra cứu hàng hải bao gồm : + Qui tắc tránh va quốc tế (COLREG) : Nội dung các điều luật, Tín hiệu đèn, Dấu hiệu, Tín hiệu âm thanh +Thông hiệu hàng hải : Thông tin cờ hiệu, thông tin cờ tay, mã morse +Hệ thống phao tiêu hàng hải +Thuật ngữ Tiếng Anh Hàng hải. +Chuyển đổi đơn vị trong hàng hải. +Lý thuyết hàng hải. +Hệ thống hải đăng toàn cầu. Các giao diện hiển thị hai ngôn ngữ : Tiếng Anh và tiếng Việt Tác giả : Vũ Công Thế. vucongthe@gmail.com

About

Navigation Almanac

This app provides a comprehensive offline celestial navigation toolkit. It calculates celestial body positions, sunrise/set times, and sky charts. It also offers tools for compass error correction and position fixing, all without requiring an internet connection.

Highlights
  • Offline celestial almanac data
  • Sight reduction calculations
  • Rise, set, and twilight times
  • Sky view chart and dome
  • Live GPS position and course
  • Compass error correction
  • Fix calculator
Features
Read full description

Navigation Almanac is a complete celestial-navigation toolkit for iPhone and iPad. It reduces a sight, tabulates the almanac data you would otherwise look up on paper, and works entirely offline - no signal, no subscription, no account. SIGHT REDUCTION Enter your position and the date and time in UTC or local time, then pick a body. You get azimuth and computed altitude, GHA, LHA, SHA and declination, semi-diameter and horizontal parallax, along with the magnetic variation from the WMM-2025 model and the current value of ΔT. ALMANAC The Sun, Moon, Venus, Mars, Jupiter and Saturn together with the 57 navigational stars, each with azimuth, altitude, hour angles and declination for the moment you have chosen. RISE, SET AND TWILIGHT Rise, meridian transit and set for any body, with civil and nautical twilight at the Sun's standard altitudes (-0°50′ / -6° / -12°), shown in UTC or local time. SKY VIEW The sky drawn as a chart of azimuth against altitude, or as a full-sky dome with the zenith at the centre. Background stars, constellation lines, and a predicted GNSS satellite layer computed from a bundled orbital catalogue. GPS Live position, course and speed over ground, altitude and horizontal accuracy, the magnetic variation at your position, and the ephemeris of the selected body. One tap fills the observer position for a reduction. COMPASS ERROR Solve gyro and magnetic compass error from an observed bearing, with variation and deviation kept separate, the way the correction is actually applied on the bridge. FIX CALCULATOR Cross two lines of position from your reductions, advance the first line for the vessel's run between sights, and read off the observed position. WORKS OFFLINE The ephemerides are computed on the device from the VSOP87 and ELP2000 series with IAU 1980 nutation - they are not downloaded. Everything above works with the phone in airplane mode, weeks from shore. SIXTEEN LANGUAGES English, Russian, Ukrainian, French, Spanish, Italian, Portuguese, German, Dutch, Polish, Swedish, Danish, Greek, Turkish, Latvian and Simplified Chinese. The navigation terminology in each was taken from that country's own nautical almanac and navigation textbooks rather than translated word for word. NAVIGATIONAL WARNINGS Warnings in force from the national coordinators of the worldwide navigational warning service, grouped by country and by NAVAREA, with the full text of every message and the positions read out of it. The feed is rebuilt every hour and the last copy stays on the device, so it is there when the signal is not. This is an experimental feature and the screen says so: the data is gathered automatically, it can lag behind the broadcast, and it can be incomplete. It does not relieve you of the requirement to receive Maritime Safety Information over NAVTEX and SafetyNET as provided for by SOLAS. Navigation Almanac is a computational aid. Carry the official almanac and tables required for your voyage.

Screenshots

Nautical Calculator Preview4 screens
Navigation Almanac4 screens

Verdict

The call

The clearest difference is ads: Navigation Almanac at none against Nautical Calculator Preview's shown. Navigation Almanac also leads on monetization model (free vs ad-supported) and update cadence (weekly vs every 2 weeks). On price, rating, in-app purchases 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

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for Nautical Calculator Preview against 5.0 for Navigation Almanac. Both are backed by a comparable volume of ratings — 1 and 3 respectively.

UpkeepUpdate frequency

Nautical Calculator Preview ships an update every 2 weeks, Navigation Almanac weekly. The most recent releases landed on October 7, 2026 and October 24, 2026 respectively.

Scorecard4 real differences · 6 level
Nautical Calculator Preview versus Navigation Almanac: the parameters behind the verdict, then further details
ParameterNautical Calculator PreviewNavigation Almanac
PriceFreeFree
Rating5.0 (1 ratings)5.0 (3 ratings)
Positive reviews—100.0% of reviews
Number of ratings13 — better
Update frequencyEvery 2 weeksWeekly — better
AdsYesNo — better
In-app purchasesNoNo
MonetizationAd-supportedFree — better
DevicesiPhone, iPadiPhone, iPad
Requires iOS17.017.0
Further details — not scored
Size33 MB4 MB
Age rating4+4+
DeveloperThe Vu CongVladyslav Zenchenko

Customer experience

Nautical Calculator Preview

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Navigation Almanac

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Nautical Calculator Preview

No in-app purchases

None

Navigation Almanac

No in-app purchases

Questions

Is Nautical Calculator Preview free?
Nautical Calculator Preview is free to download, with no in-app purchases.
Is Navigation Almanac free?
Navigation Almanac is free to download, with no in-app purchases.
Which has better reviews, Nautical Calculator Preview or Navigation Almanac?
Nautical Calculator Preview and Navigation Almanac are both rated 5.0 out of 5 on the App Store, from 1 and 3 ratings respectively.
Do Nautical Calculator Preview or Navigation Almanac have ads?
Nautical Calculator Preview shows ads; Navigation Almanac does not.
Which is updated more often, Nautical Calculator Preview or Navigation Almanac?
Nautical Calculator Preview ships an update every 2 weeks, and Navigation Almanac weekly. Most recently, Nautical Calculator Preview was updated on October 7, 2026 and Navigation Almanac on October 24, 2026.

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