Using SeaNav

SeaNav lets you plan and navigate your trips in real time with the latest Digital Vector Marine charts. Charts are stored in the app so you can use SeaNav to help navigate even when you have no mobile coverage.


Tap on an object; buoys, lights, bridges, ships etc. to get information about them. Zoom in and out and pan using pinch and drag gestures. As you use the app it will automatically download and store the charts for the area you are viewing. It can take a bit of time to download and draw new charts the first time you use the app, especially on an HD display. Subsequent viewing is much faster. The level of detail on the charts changes as you zoom in and out. If you can't see any buoys or depth areas try zooming in further.

A long press will reveal a crosshair and a popup with depths, links to information about tides, moon and sun times and weather for the area plus links to any objects that are near the crosshair. Tapping again leaves the crosshair showing so you can drag the map to get a particular point under the crosshair and tap again to get information about it.

SeaNav Demo Mode

Demo Mode lets you experience SeaNav's navigation features on land. Select User Guide and FAQ in settings and then slide the Demo Mode setting switch to ON (right) to position you at sea ready to navigate our demo route and try out the features below. You can also read these instructions on a web page using the following link Demo Guide. Its may be helpful to read this page on your laptop or other device at the same time as running this demo on your iPad or iPhone.

N.B. Slide the Demo Mode switch back to OFF to return to normal use. Sliding it OFF and then ON again will position the demo route at the beginning again.

N.B. Tide and Weather information requires an internet connection. You can download upto a years Tide information for any area as iCalendar events to store for offline use in your calendar.


Tap this to start navigating the currently visible route or free sail without a route set. When on (white boat icon), your position will show on the maps as a boat icon with heading and speed vectors. Next waypoint, Course over ground (COG), Speed over ground (SOG), Vector Made Good (VMG), Estimated Time of Arrival (ETA), Distance and bearing to next Waypoint and current Latitude and Longitude will be displayed and updated in the head up display. An audible alarm will sound as you reach a waypoint and routing automatically moves onto the next waypoint. On reaching your final waypoint a summary of the trip details is shown with distance covered, time taken etc. Route tracking and waypoint monitoring will continue to run in the background when the app is closed. You can interuppt and resume a route exactly where you left off at any time by toggling the Sailboat icon.

N.B. If you have Boat Beacon - AIS Marine Navigation you will be invited to set Collision detection and trip details when you start navigating.

N.B.B. GPS uses a lot of battery. SeaNav will run for upto 5 hours in navigating mode on a full charge. If running on battery only, battery status reminders will be sent when the battery gets low.

Augmented Reality View

Tap the "eye" icon at the top left to switch AR mode on, then tilt your device up to see a live camera of the scene and boats around you. As you turn round and view buoys and ships, their name, range and bearing will popup when they are in the center of the view. You can also tap on them to get more information. Tilt back down to see the map view. Tapping the "eye" icon again turns AR mode off. You can pinch to zoom the map or camera views.

In AR mode our unique "AR Lock On" feature lets you select a ship or buoy on the map view and then easily locate it in the Camera view using a grey arrow to tell you which way to turn to spot it when its not directly in view. Your course (yellow line) and route to next waypoint (blue line) will also be visible overlayed on the camera view.

Ships are color coded based on their type e.g. Sailing boats are white, Pleasure Craft magenta, etc. See the Map Legend for full details. A vector points forward showing where each boat will be in 2 minutes time based on its current Speed and Course. Ships move in real time across the map and in the AR view. Tap on a ship or buoy to get more information and tap on the right arrow to get even more including speed, course, distance, bearing, picture etc. The horizon is set by the zoom scale of the chart view - e.g. zoom out on the chart view to see further out in the Augmented reality view.

AR photo from the Isle of Wight ferry.

Wind Instruments

SeaNav supports Wind data from GoFree, NMEA over WiFi (see AIS and GPS Link in settings) or via Bluetooth with the brilliant SailTimer Wind instrument which is completely wireless, no power of data lines, so the install is far simpler than for other marine wind vanes.

In SeaNav tap the top right IPC (Instrument Panel Cluster) button on the chart view to see the gauges and GPS status.


The Speed gauge on the left shows Apparent Wind Speed (AWS) in Knots and the outer dial shows Beaufort scale color coded with green being great sailing conditions and red being heave to and batten down the hatches.

Digital readouts of Speed over ground (SOG), Course over ground (COG), AWS, True Wind Speed (TWS),  Apparent Wind  Angle (AWA), True  wind angle (TWA), Apparent Wind Direction (AWD) and True Wind Direction (TWD)  are given. The GPS light is green when it has a good GPS signal and red when it doesn't. Tap the GPS indicator to get more information.

The Wind direction gauge on the right shows Apparent Wind Direction (AWD) with the big Red needle against the outer red compass dial. Boat heading is shown against the red compass assuming the iPhone/iPad is pointing towards the bow. The Apparent Wind Angle is then read off the white inner dial.  True Wind Direction (TWD) is computed from  the iPhone's GPS COG and SOG with the blue marker and red, port and green, starboard layline markers (assuming 45 degree best angle of attack ) against the red outer compass dial.   True wind angle (TWA) with the blue maker against the inner white dial, again assuming iPhone heading is correct. The dials also work in portrait mode.

This also works with the free  Pebble Watch  SeaNav app showing AWS/AWA and TWS/TWA and will also drive the watch even when SeaNav is in the background so long as SeaNav is in sailing mode (sailboat icon bottom left on map/chart screen).


You can get the SailTimer WindInstrument with a discount from Pocket Mariner here :-

Location and Compass

Toggle between centring on your current position or showing the compass display. Tap once to lock the center of the map to your current location - dragging the map in this mode turns it off too (but not when compass is showing). Tapping the button again will show a compass rose, and pressing again will clear the location lock. See Compass mode in Settings for selecting Bearing, Course up or North up compass display.


Search for a port or place by name or latitude and longitude. Tapping a result jumps you to its position on the map and highlights it. Latitude and longitude can be entered in the following formats :- or DD MM.MMMM N,DDD MM.MMMM W (e.g. 37 48.915 N, 122 23.044 W) or DD MM.MMMM,DDD MM.MMMM or DD.DDDDD,DDD.DDDDD with latitude first and longitude second separated by a comma. West and South can be entered as negative numbers e.g. 51.2345,-2.12345 for 2.12345 degrees West. Tapping search will jump to the lat and long if they are in a valid format.

Routes, Tracks and Favorite places

Create new routes, edit existing ones, select which route to use or view, manage tracks that you have recorded from previous trips and share routes with friends and other devices. Favorite places can be entered as a route with a single waypoint.

Routes are entered as a series of Waypoints. Tap and hold on the Map to place waypoints. Long press on a waypoint in Route Edit mode to drag it to another position. When selected you can also delete a waypoint. You can edit the route name and tapping the reverse button will reverse a route. Hit the Done button when you have finished editing.

You can go back and edit routes and select which route is the currently selected one. Tap the sailboat icon to start sailing a route. The nearest waypoint to your current position will be selected as the active waypoint. You can manually set the active waypoint by tapping it. Routes are not editable when a Route is active (e.g Sailboat icon is selected). If you need to change your route during a trip just de-select the Sailboat icon by tapping to, edit the route and then tap the Sailboat icon again. You will be returned to where you left off.

Tap the share button in the route details view to email your route as a kmz file. This can then be viewed in Google Earth and other copies of SeaNav. If you receive a kmz file in an email on your device, tap on it to open it in SeaNav. This is a simple way of sharing routes between your iPhone and iPad devices.


Use the ruler to measure distances and bearings between points on the map. Drag and drop the green and red pins to select the end points.

SeaNav Apple Watch App

SeaNav on iOS 8.2 and later includes our free Apple Watch SeaNav app which provides live navigation data wherever you are on your boat. Check your Speed, Course, Waypoint distance, bearing and time at the flick of your wrist. It also includes a compass display, live AIS radar map, race countdown timer and a night mode switch which also acts as a handy wrist torch.

Help and Settings


SeaNav version 3.5 onwards supports the amazing ActiveCaptain database which  includes up to date location and details on tens of thousands of Marinas, Anchorages, Local Knowledge and Hazards in the US, Canada  UK, Ireland and Europe geographically overlaid on our charts as well as, thousands of reviews from other boaters.

Tap this to Login to your Active Captain account and install the database. If you don’t already have an account you can sign up for free in an instant here:-

Please note that it can take a few minutes the first time you download and install the database - depending on your internet speed. Please be patient, you can still use the rest of the app while it is downloading and if you leave the app for another application the install will resume where it left off the next time you open SeaNav.

ActiveCaptain icons are colour coded red for marinas, green for anchorages, blue for local knowledge and yellow for hazards. They start to appear as you zoom in to an area at greater than 1:600,000 scale.

Once logged in and installed, you can toggle the ActiveCaptain layer on and off using this setting too. To update the data , just visit the ActiveCaptain setting form and an automatic sync of the latest data will be started in the background if there is new or updated data available.

Manage Routes

Browse,Select, Share, reverse, rename waypoints and delete routes

Manage Map Layers

You can choose what information to show on the map; Buoys, Lights, Depth contours, Depth soundings, Wrecks, Rocks, Anchorage areas, NOAA Weather Buoys, Traffic Separation zones etc. Turn off layers to de-clutter the display and only show what is important at the time. You can set the maximum depth to display details at in Advanced Settings - Max Display Depth :- 20m, 50m or All.

If you have Boat Beacon you can also view live AIS ship information on the map. Ships are color coded based on their type e.g. Sailing boats are white, Pleasure Craft magenta. See the Map Legend for full details. A vector points forward showing where each boat will be in 2 minutes time based on its current Speed and Course. Ships move in real time across the map. Tap on a ship to get more information. Collision detection, alarms and location sharing are set and handled in Boat Beacon.

N.B. To see individual Depth soundings you need to zoom in to 1:20,000 or better.

Manage Charts

Charts are automatically downloaded and stored as you pan and browse the map view. You can use "Manage charts" to view which charts cover which areas, which charts have been installed and manually select new charts to download including all charts for the current view. You can also remove charts to free up space to download other charts. You can store the charts for the whole of the UK or several US States. They can then be used even when you have no mobile coverage.

The cog wheel icon at the bottom right opens a table view listing all the charts you have installed.

Already downloaded and installed charts are outlines in green. A solid outline shows the currently selected chart. Red outlines are charts that haven't been downloaded. Tap a chart area to select it.

Display mode

Select map, satellite or hybrid map overlays. By default, Depth overlays are not shown in satellite mode to allow satellite image details to be seen. Depth contours are still displayed. You can manually turn the Depth overlays back on when in Satellite mode. Depth Overlays are automatically defaulted to show when back in Normal mode.

Compass mode

When the compass is on the map display will rotate with either your bearing (magnetic or true north direction), your course or be locked to showing North up. Course up means the map will orient in line with your boats course over ground.


SeaNav automatically connects to your Simrad NSS, Lowrance HDS or B&G Zeus via WiFi GoFree and displays Waypoint, Course, Layline, Buoys and Ship AIS data over your iPhone iPad live camera view.

The first time you use GoFree you will need to select the MFD you are connecting to, after that SeaNav will connect automatically if it can see it on the network. To make the initial connection go into settings, tap on GoFree (see screenshots below) and you should then see a list (usually just one entry) of the MFD’s SeaNav has found on the network. Select the one you want by tapping on it. You should now see a connected message and the name of the MFD connection highlighted in orange in the Settings screen meaning it has successfully connected. Pop out to the Chart view and go back into settings and it will now be green if it has received data from the MFD.

If you want to stop using GoFree then tap the GoFree setting in Settings and then tap the X at the top right  of the list of devices.

  Pebble Smartwatch

SeaNav also hooks up with the amazing Pebble Smartwatch to provide live navigation data on your wrist wherever you are on your boat. Check Speed, Course, Waypoint, Wind, AIS radar, SailSteer and times and get Collision(CPA), Waypoint and Countdown timer alarms. If you have a Pebble Watch, switch on here to download our free Pebble SeaNav watch app. If not - maybe get one :). There is a user guide for the Pebble Watch SeaNav app here:- Pebble Seanav User Guide

Advanced settings

Getting Help

How do I contact you with Suggestions and Questions?

We're always happy to hear your ideas on how we should improve our products - please send an email to

Are you on Twitter?

We sure are - follow @seanavapp to get our latest news.

Anything Else?

Pocket Mariner have other great apps for iPhone and Android- if you're a fan of SeaNav you are sure to enjoy apps like Boat Beacon which provides real time Marine AIS ship position receive and transmit and Compass Eye the first fully Gimballed iPhone Bearing compass with zoom and overlaid gps information.

And finally, you may like to know that Pocket Mariner can develop mobile applications for your company - if you have a project you'd like to discuss, please email us at

Third Party Licenses and Notices

NOTICE: The UK Hydrographic Office (UKHO) and its licensors make no warranties or representations, express or implied, with respect to this product. The UKHO and its licensors have not verified the information within this product or quality assured it.

NOTICE: US marine charts are derived from the official NOAA ENC� vector chart data.


SeaNav has been licensed to you under the Apple End User License Agreement (EULA)

Please note this program is distributed in the hope that it will be useful, but with NO WARRANTY. It is for basic navigational purposes only and is not intended to be relied upon in situations where precise location information is needed or where erroneous, inaccurate or incomplete location data may lead to death, personal injury, property or environmental damage. Neither the Application Provider, nor any of its content providers, guarantees the availability, accuracy, completeness, reliability, or timeliness of information or location data displayed by any Services.

N.B. This is not an AIS transponder. You will not be visible to other ships on their AIS systems unless they also use data from the same land based AIS networks.

The accuracy of digital compass headings can be affected by magnetic or other environmental interference, including interference caused by proximity to the magnets contained in the iPhone earbuds. The compass may need to be calibrated from time to time. When the device displays the calibration alert, move the device in a figure 8 motion until the calibration screen disappears. See Apple support for more information.