The best boat navigation tools: apps, charts and instruments

In 2026, sailing a catamaran without a navigation app on your phone or tablet is like setting off without a chart. Navionics remains the global benchmark for digital marine charts, but the right digital setup depends on your sailing area, your skill level and the combination of tools you bring together aboard. Here is what the Sailoe teams use and recommend, after years of sailing in the Seychelles, in Guadeloupe and in the Mediterranean.

What are the essential navigation tools to have aboard a catamaran?

Aboard a catamaran, the bare minimum includes a charting app with offline charts, a dedicated marine weather app and the boat’s physical instruments - GPS, VHF, depth sounder, compass. These three layers complement one another; none replaces the others.

The charting app: the modern pocket GPS

A marine charting app turns your smartphone or tablet into a portable chartplotter. It shows your real-time GPS position on a digital marine chart and flags shallows, restricted zones and seamarks. Its decisive advantage: the charts download before departure and work without any network. Off Praslin, without a single bar of signal, it is your downloaded chart that guides you into an anchorage with 2.5 metres under the keel.

The weather app: different from charting, complementary

A marine weather app is not an accessory, it is the second tool to have up to date before every outing. It gives you wind, swell, gusts and moving systems over several days. Combined with the charting app, it lets you cross-check the planned route against the actual conditions expected and decide on a plan B before casting off rather than out at sea.

Physical instruments: what digital cannot replace

A phone falls overboard, a battery runs flat, a screen becomes unreadable in the sun. The boat’s physical instruments - built-in GPS/chartplotter, fixed VHF, depth sounder and magnetic compass - are there for exactly that. They work in all weather, without relying on a third-party app or a connection. French regulations understood this well by making them mandatory beyond a certain distance from shore.

Navionics Boating: why is it the benchmark for catamaran sailors?

Navionics Boating is the most widely used navigation app in the world among leisure sailors. Acquired by Garmin in 2017, it offers highly detailed worldwide marine charts, an offline mode, dock-to-dock routing and a community of sailors who feed the data in real time. On our Lagoon catamarans, we use it paired with an onboard Garmin chartplotter: it integrates natively with the boat’s instruments.

What Navionics does better than the others

The strength of Navionics rests on four pillars. Its worldwide cartography is among the most detailed on the market, enriched by SonarChart HD data - a crowd-sourced bathymetry continuously fed by the community of sailors. The offline mode is complete: charts, waypoints, tracks, everything is available without a network. Dock-to-dock routing automatically calculates the optimal route between two ports, taking depths and obstacles into account. GPX export finally makes it easy to share routes with other sailors or import them to an onboard chartplotter.

The limits to know before subscribing

Navionics went through a significant price revision in 2024 since its integration into Garmin. The subscription for Western Europe is now 50 EUR/year; full Mediterranean coverage (Mediterranean and Black Sea) reaches 100 EUR/year - compared with much lower prices before 2024. The interface, very rich, can throw off beginners during the first few sessions. The app also lacks a native anchor alarm and a built-in logbook: you need complementary apps for those uses. Its Google Play rating reflects these pricing and interface frustrations: 2.8/5 across 47,950 reviews, against 4.8/5 for iNavX on the App Store.

Which other navigation apps should you use aboard?

Navionics is not the only option, and depending on your sailing area, other apps may prove better suited or more affordable. iNavX, C-MAP Embark and Navily each answer a specific use.

iNavX: for experienced multi-chart sailors

iNavX is the favourite app of offshore sailors who want to choose their chart provider. It is compatible with many chart publishers and integrates real-time AIS tracking, which makes it a powerful tool for long passages. Available on iOS and Android, it shows a rating of 4.8/5 on the App Store, which reflects its reliability in real conditions.

C-MAP Embark: the well-rated free alternative

C-MAP Embark is the ideal entry point for a beginner or a sailor who wants to try without spending. The app is free with paid options, and earns 4.3/5 on Google Play (14,000 reviews). Its modern interface is more accessible than that of Navionics. C-MAP chart data is recognised across the entire Atlantic and Mediterranean basin.

Navily: the must-have for anchorages in the Mediterranean

Navily is a community app specialised in anchorages and stopovers: more than one million users have listed over 35,000 anchorages and ports across Europe. It gives practical information on each spot - wind protection, holding quality, local regulations, presence of mooring buoys - and lets you book berths. In the Mediterranean, it is essential for anticipating the saturation of anchorages in high season. In the Seychelles or in Guadeloupe, our teams know the anchorages by heart, but as soon as you sail in the Med, Navily usefully complements Navionics.

App	Price	Strengths	Ideal for
Navionics Boating	50 EUR/year (Western Europe) - 100 EUR/year (full Med)	Worldwide cartography, offline, auto routing	Sailors seeking the most complete chart
iNavX	Paid (multi-chart)	Multi-provider, AIS, very reliable	Experienced, offshore sailors
C-MAP Embark	Free (paid options)	Modern interface, good rating, accessible	Beginners, first setup
Navily	Free (Premium available)	35,000+ anchorages, community, port booking	Mediterranean sailors
OpenCPN	Free (open source)	Very complete, configurable	Technical sailors, navigation desks

How can you forecast weather at sea from your phone?

Marine weather cannot be improvised from mainstream bulletins: you need specialised models that read wind, swell, currents and tides together. Windy is the ideal free entry point; PredictWind is the benchmark for offshore sailors.

Windy: the real-time wind map, free and reliable

Windy is the benchmark for marine weather visualisation accessible to everyone. The app is free and relies on the ECMWF model, the most accurate available in open access. It overlays wind, swell, precipitation and up to seven different weather models in layers. Before every outing from Mahe, the skipper checks the wind and swell on Windy: the layered display is immediately readable, even on a phone. The Premium version at 19 EUR/year gives access to models in one-hour steps (against three hours in the free version) and to a partial offline mode.

PredictWind: the offshore benchmark for long passages

PredictWind is the weather tool of sailors who make passages lasting several days. It generates high-resolution GRIB files and offers an offshore routing module that calculates the optimal route based on 7-day forecasts. Its subscriptions range from a free version to advanced plans for professional sailors. It is the standard tool of crews crossing the Atlantic or sailing in French Polynesia.

Which physical instruments are mandatory on a catamaran in France?

Mobile apps complement but do not replace the boat’s physical instruments. In France, the regulations (Division 240) require a fixed VHF from 6 miles of shelter and a lit magnetic compass. AIS, the depth sounder and a dedicated GPS/chartplotter make up the standard equipment of any serious charter catamaran. All our Sailoe catamarans are fitted with the complete electronics suite: you have nothing to bring on the instrument side.

GPS/chartplotter: the heart of the navigation station

The GPS chartplotter is the central instrument of the navigation station. It displays the boat’s position on a marine chart, calculates the route, flags shallows and records the track. The Division 240 regulations require up-to-date cartography aboard for any navigation. An entry-level chartplotter starts at 220 EUR; integrated multifunction units (sounder + charting + AIS) exceed 2,500 EUR.

AIS and VHF: see and be seen

The fixed VHF is mandatory from 6 miles of shelter and up to 60 miles depending on the applicable division. Its budget ranges from 80 to 600 EUR depending on the model. AIS (Automatic Identification System) is not mandatory for leisure boaters under 300 GT, but it is strongly recommended: a Class B transponder (600 to 900 EUR) broadcasts your position every 30 seconds and shows the cargo ships around you on the chartplotter. The MMSI declaration with the ANFR is free and essential before activating AIS.

Depth sounder: knowing the depth under the keel

The depth sounder measures the depth under the hull in real time by ultrasound. It is not required by Division 240 but it is standard on any cruising catamaran - often integrated directly into the multifunction GPS chartplotter. When approaching an unfamiliar anchorage in the Seychelles, with chart data that is sometimes imprecise on coral bottoms, the depth sounder is the only instrument that tells the truth about what is happening under the keel.

How can you plan your catamaran route with digital tools?

Planning a catamaran route starts ashore, well before casting off. Digital tools let you plot your route, check the weather, download your charts and file a safety plan - a step often overlooked by beginners.

Filing your navigation plan before departure

Before any offshore departure, filing a navigation plan with the CROSS (Regional Operational Surveillance and Rescue Centre) is a simple, free and recommended procedure. It consists of communicating your itinerary, the number of people aboard and your estimated arrival time. In case of prolonged radio silence, the CROSS knows where to look for you. This step is done by VHF channel 16 or by online form depending on the region. For our crewed organised cruises, this protocol is part of our skippers’ systematic departure checklist.

Downloading your charts in advance: the offline reflex

The golden rule before casting off: download all the charts for the area in offline mode, from the harbour, with Wi-Fi. At sea, the mobile network disappears as soon as you move away from the coast, and downloads on patchy 3G can take hours. On Navionics as on iNavX, the download area is set manually: choose wide, include alternative anchorages and ports of refuge. After dark, at anchor in Les Saintes, is not the moment to try to update your charts.

To take your cruise preparation further, find our weather tips for your Mediterranean cruise and our full article on preparing a long voyage in a catamaran.

FAQ - Frequently asked questions about boat navigation apps

Is Navionics free?

The Navionics Boating app is free to download on iOS and Android. However, access to the marine charts and the full features requires a paid annual subscription. Since the 2024 price revision by Garmin, the subscription for Western Europe is 50 EUR/year; full Mediterranean coverage (Mediterranean and Black Sea) is 100 EUR/year. A free trial period is available on installation.

What is the price of a Navionics Boating subscription?

The price depends on the geographic area chosen. Since 2024, Garmin has harmonised most subscriptions at 50 EUR/year. Mediterranean and Black Sea coverage is billed at 100 EUR/year. For the Western Mediterranean only, a partial subscription is available at around 19.99 EUR/year. The physical SD cards for GPS chartplotters are sold separately.

Which alternative to Navionics for sailing at sea?

The main alternatives are C-MAP Embark (free, modern interface, 4.3/5 on Google Play), iNavX (multi-chart compatible, ideal for experienced sailors, 4.8/5 on the App Store), Savvy Navvy (intuitive all-in-one, paid subscription) and OpenCPN (open source, free, very complete but requires initial configuration). For anchorages in the Mediterranean, Navily is complementary rather than a direct alternative.

What is the best free app for sailing at sea?

C-MAP Embark offers the best features-to-free ratio: detailed charts, integrated weather forecasts, real-time GPS tracking and offline mode. Navily is free for access to anchorages and ports. Windy remains the free benchmark for marine weather. OpenCPN is free and very complete, but requires a more technical initial configuration.

Whether you are preparing your first catamaran charter or a passage to the Seychelles, the right digital setup is built in layers: a solid charting app, reliable weather and onboard instruments that meet the standards. To set off with a clear mind, all our Lagoon catamarans leave the base with the complete electronics suite already in place. All that is left is to download your charts. Request a quote by writing to charter@sailoe.com or call +33 2 97 84 61 61 - reply within 24h.