OpenSeaMap vs Sailing Master M
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
OpenSeaMap
This app provides a free, worldwide nautical chart with detailed sea information, including lights, weather data, and harbor details. It offers chartplotting, waypoint management, and offline map caching for navigation. Users can mark locations, enter coordinates, and adjust chart zoom for optimal viewing.
- Free worldwide sea chart
- Chartplotting with tracking
- Waypoint creation and export
- Offline map caching
- Mark and search locations
- Adjustable chart zoom
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OpenSeaMap is a worldwide Opensource-project for creating a free nautical chart. Founded in 2009 the project gained a lot of attention lately adding more and more nautical information for free. Not even lights and other nautical infos are provided, but also more and more info layers like weather data, information about harbours and so on. As an add on to the OpenStreetMap this provides all missing info for nautical activities. OpenSeaMap is part of OpenStreetMap and uses the same database. FEATURES: - Free worldwide sea chart (incl. HD chart graphics) - Search for geolocations worldwide - Chartplotting with continuous tracking - Waypoints can easily be created, edited, deleted & exported - Mark locations in the chart - Zoom chart optically to fit your preferred reading size - Enter coordinates directly to be displayed in the chart - Offline caching of up to 1 million map tiles - Cleanup of chart cache data at any time To ensure future development and support of the OpenSeaMap app we encourage you to buy the In-App-Product "PRO". This will help keeping new updates and features coming. DISCLAIMER: OpenSeaMap is part of the OpenStreetMap and uses the same database. As an experienced navigator you should NEVER rely your descisions on one source of information alone. Please keep in mind that the OpenSeaMap can not replace official sea charts on bord of your boat. Please use the OpenSeaMap app only in conjunction with official sea charts and conforming to national and international regulations. Please recognize that no depth information is provided by this product. IMPORTANT: The continued use of the GPS can significantly decrease the battery level.
Sailing Master M
This app provides comprehensive sailing data and performance optimization on various Apple devices. It displays over 35 sailing measurements from boat instruments, polars tables, and nautical charts, offering detailed wind, route, and map views. Connectivity is established through NMEA 0183 Wi-Fi gateways.
- Configurable data displays
- 35+ sailing measurements
- Wind, route, and map displays
- NMEA 0183 Wi-Fi connectivity
- Polars table integration
- Nautical chart overlays
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Sailing Master M offers comprehensive sailing data and performance optimization information on iPhones, iPads, iWatches, and ActiveLook smart glasses. The application provides configurable pages and data displays, utilizing over 35 sailing measurements from the boat’s instruments, polars tables, and nautical charts. On phones and pads, the Data and Analog Displays can include minimum and maximum values and time series graphs. The Wind Display provides wind, heading, route, and speed information. The Route Display shows the expected wind conditions on the next legs. The Map Display shows the vessel with direction, tacking and downwind laylines on a nautical chart, or the wind laylines in another location. The connectivity is through NMEA 0813 Wi-Fi gateways such as B&G Vulcan, Zeus, GoFree, Yacht Devices, Signal K, Actisense, and ShipModul. The application has evolved from its initial focus on NMEA data display to encompass a comprehensive suite of features. Consequently, the app’s name has been revised from 'Display0183M' to 'Sailing Master M'. For further information, please refer to the user’s guide available on the app’s website or within the app itself. Terms of use: The app is delivered under the Apple End User License Agreement (EULA, https://www.apple.com/legal/internet-services/itunes/dev/stdeula/) The following libraries and services are used: - Kitura/BlueSocket, published under the Apache 2.0 license - A modified version of GPX package, published under BSD 3-Clause License and copyrighted by Ioannis Silks - OpenStreetMap licensed under the Open Data Commons Open Database License (ODbL, https://opendatacommons.org/licenses/odbl/) by the OpenStreetMap Foundation Licence, and ©OpenStreetMap contributors. OpenSeaMap, which is licensed under the Open Data Commons (ODbL) license, and ©OpenSeaMap contributors The supported NMEA 0183 sentences are: - BWR: Bearing and distance to waypoint - DBS: Depth below surface - DBT: Depth below transducer. - DPT: depth of water. - CGA: Global Positioning System Fix data - GLL: Geographic position Latitude/Longitude - HDG: Heading magnetic - HDM: Heading magnetic - HDT: Heading true - MWD: undocumented, wind direction, wind speed - MTW: water temperature °C - MWV: Wind speed and angle (A,T) - RMB: XTE, range to destination, bearing to destination, destination closing velocity . - RMC: Speed over ground - RSA: Rudder sensor angle - VHW: Water speed and heading - VLW: Distance travelled through water - VPW: Speed - measured parallel to wind - VTG: Course over ground (T or M), speed over ground - VWR: Wind direction (A), wind speed (A) - WCV: Waypoint closure velocity - XDR: air temperature (°C), water temperature (°C) and barometric pressure (mbar). - XTE: Cross track error The data items from NMEA and polars are: - Waypoint bearing - Waypoint distance - Time to Waypoint - VMG waypoint - Cross track error - Depth - Heading - Heading - Course - Course - Water speed - Speed over ground - Water temperature - Air temperature - Air pressure - Wind speed apparent - Wind angle apparent - Wind speed true - Wind direction - Wind direction - VMG Wind - Latitude, Longitude - Waypoint laititude, longitude - Water Distance after reset - Total water distance - Ground distance after reset - Total ground distance - Velocity made good towards wind - Heel - Rudder - Boat target speed through the water - Boat speed of target speed (%) - Beat VMG boat target speed through the water - Run VMG boat target speed through the water - GPS based trip distance - Leeway
Screenshots
Verdict
The clearest difference is rating: Sailing Master M at 5.0 against OpenSeaMap's 1.0. On price, ratings volume, update cadence and ads 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
Both are free to download. OpenSeaMap sells 1 one-off in-app purchase and Sailing Master M sells 1 in-app purchase, starting at $11.99 per year. Whichever you choose, the download price is not the number that matters.
Sailing Master M holds the better App Store score, 5.0 against 1.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on October 21, 2026 and October 13, 2026 respectively.
| Parameter | OpenSeaMap | Sailing Master M |
|---|---|---|
| Price | Free | Free |
| Rating | 1.0 (1 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 38.3% of reviews | — |
| Number of ratings | 1 | 1 |
| Update frequency | Every 2 months | Every 2 months |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Devices | iPhone, iPad | iPhone, iPad, Apple Watch — better |
| Requires iOS | 18.6 | 17 — better |
| Further details — not scored | ||
| Size | 13 MB | 25 MB |
| Age rating | 4+ | 4+ |
| Developer | appdoctors UG | Pekka Leppanen |
Customer experience
OpenSeaMap
Sailing Master M
In-app purchases
OpenSeaMap
- OpenSeaMap Professional$1.99
Sailing Master M
- Pro annual14 Days trial$11.991 Year
Questions
Is OpenSeaMap free?
Is Sailing Master M free?
Which has better reviews, OpenSeaMap or Sailing Master M?
Do OpenSeaMap or Sailing Master M have ads?
Which is updated more often, OpenSeaMap or Sailing Master M?
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