Here are the answers to some of the questions users have been asking…
Will SeaNav work if I don’t have an internet connetion?
Yes. SeaNav only requires a data connection to download new charts or to receive live ship , tide or weather information. Once downloaded the charts are stored in the app so you can use the app to help navigate even when you are offline and out of reach of the internet. You can also download Tide Tables for any period upto a year ahead and store those in your Calendar app as iCalendar events.
Does SeaNav work in the background?
Yes, if you are “Sailing” – have the Sail Boat Symbol, bottom left, selected – SeaNav will continue to update your position and track and alarm waypoints even when you leave the app.If you want SeaNav to stop and not use any power when you close the app or switch to another app make sure the “On my Boat” symbol is off – greyed out.N.B. When navigation is enabled the iPhone GPS system is active and will use more battery power while the app is running even in background. It will last upto 4 hours on a full battery charge.
How do I stop SeaNav running in the Background?
Tap the sailboat icon at the bottom left to turn navigation on and off. When on – it will also run in background – when off it won’t.
How do I see Ships in SeaNav? How do I get Collision detection?
You can get live Ship data via our Internet AIS service or by using a local AIS feed. On Mac this can be via USB, UDP or TCP, in iOS via Wifi. On iOs SeaNav gets its Ship AIS data from our companion app Boat Beacon . Boat Beacon also provides Collision Avoidance and alarms. If you already have BoatBeacon installed you will also be able to see live ships overlaid on the SeaNav Chart. If you don’t, just get Boat Beacon from the iTunes store to get Live Ship display in SeaNav and real time collision avoidance and alarms. You can quickly switch back and forth between SeaNav and Boat Beacon screens using the app icon on the left hand side of the screen, eg. to set Boat Beacon active in the background when you start navigating in SeaNav. For Mac you can enable internet AIS in preferences.
Can I share my AIS data with others like I can with Ship Plotter?
Yes on our Mac version. Set AIS Share on Preferences to share data over UDP or TCP with up to 2 destinations. Please consider sharing your live AIS data with our Internet Boat Beacon AIS service. We can provide you with a dedicated port and web page to view your AIS data on from anywhere. We can also set up additional shares to other services for you like Marine Traffic.
How “real time” is SeaNav?
SeaNav receives data from a collection of different sources. The GPS fix is updated every 2s and comes directly via the satellites. Ship AIS data comes via the internet and is timestamped.The majority of the AIS data is fed directly as it is received by the shore stations and typically there is less than a 1 second delay between the ship sending the transmission and it being available to SeaNav via the internet. You can check which areas have direct feeds on this map Direct coverage The other stations report once a minute, they accumulate the data over a minute and then send it to us. So on average these reports are 30s behind real time.
The AIS standard has different reporting times. Boats at anchor and travelling at less than 3 knots only report their position every 3 minutes. Ships moving at over 23 Knots send updates every 2s. A boat travelling at 30 Knots would have a placement error of about 14 meters after 2s and 200m after 30s. SeaNav interpolates the positions between updates to improve the placement for boats on a slow refresh rate.
How do get my latitude and longitude?
Just tap on your boat symbol when navigating and it will display your current Lat and Long.
Can I add my own waypoints and tracks?
Yes, that’s at the core of SeaNav! Tap the Route icon in the middle bottom of the screen to add new routes or edit existing ones.
How old is the Chart data? How do I update the charts?
Yes, we get the latest updates from the NOAA and the UKHO and roll these out 4 times a year.
You will get any updates automatically when you view a chart.
The US chart updates are free for life. For the UK and Ireland the UKHO license restricts updates to 12 months at a time. If you want to extend this there is an in app purchase option to extend this for further 12 month periods.
What other areas do you cover?
We currently have charts for the US and UK. We will be rolling out Spain, Netherlands and Australia as soon as we can obtain the chart licenses. If you want us to cover your area please let us know, the more votes the more chance we will prioritise it.
How do I use zoom?
Use your fingers to pinch in and out. Tap the compass icon to toggle pan mode which lets you pan around. On the mac use pinch on the track pad or the + and – buttons.
“I see no ships”?
SeaNav shows all the ships and Boats Boat Beacon can see. Boat Beacon uses ship data provided by a network of
shore based AIS receiving stations. You can check the coverage for your area in SeaNav or via this web site Total coverage
We have coverage for most of the popular coastal areas and coverage is constantly increasing. If your area isn’t covered, please let us know by emailing
email@example.com, especially if you would like to share your AIS data with us to improve coverage.
How much data does it use?
The app only uses data if you have the Ships layer or the NOAA Weather buouys layer on. The data rate is low – it depends to a certain extent on how many boats are in view and how much you change the map position/scale. On average it receives about 3 kbytes and sends about 1/2 kbyte every minute. Although it’s a pretty low data rate (500bps) it can mount up if left on continuously. e.g. if left on continuously for a 6 hour trip that would be just over 1 Mbyte of data.
If you are worried about the cost of mobile data when travelling abroad you can normally get deals at around $3 for 30Mb per day or $5 for 70MB per week using a local PAYG sim.
I want the compass to show True North readings rather than Magnetic?
Go to Advanced Settings and set the “True North” switch as you require. The label shows the current magnetic variation for your locale in brackets (e.g. (2W)). All bearings as well as the compass display are automatically adjusted to the new setting. When True North is set on the compass and bearing readings will show a N after the number. N.B. Using True North requires the iPhone GPS system to be powered up and will consume more battery power.
Will SeaNav work on an iPad?
Yes. You can plan routes and view maps and live ships etc. With a GPS enabled iPad (either built in gps or via Bluetooth) you can also navigate in real time.
If it is a WiFi only iPad you can use a Bluetooth GPS dongle – we recommend and have tested the Garmin GLO with SeaNav.
Can I take a picture? How do I share my position?
Use the share button at the bottom right of the toolbar (iPad only). You can share via email, twitter, facebook and also print and save a photo to the camera roll.
When using the compass you may see the message, “Move away from any interference, or re-calibrate by waving in a figure 8 motion.”
The built-in digital compass works just like a magnetic-needle compass. 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, rotate the device in a figure 8 motion until the calibration screen disappears.
See iPhone Compass Calibration for additional information.
Will SeaNav run on an iPhone 3GS?
Sorry, no – SeaNav requires iPhone OS 6 or later.
This application should only be used for basic navigation assistance. Never rely solely on the digital compass for determining direction,
proximity or distance. The user is responsible for the prudent use of information provided by this application and must not use it for direct
navigation. 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 ear-buds. Location-based applications depend on data services. These data services are subject to change and may not be available in all geographic areas, resulting in digital compass headings, directions or location-based information that may be unavailable, inaccurate, or incomplete.
You assume all responsibility and risk for the use of this software. The author assumes no liability for damages arising from use of this program.
DO NOT RELY ON THIS APPLICATION FOR DECISIONS THAT CAN RESULT IN HARM TO ANYONE OR ANYTHING.
Can I send you feedback and ideas?
Yes, definitely – we’d love to know what you like (and don’t like) about SeaNav – the best way is to send an email directly to
firstname.lastname@example.org. We’ll do our best to get back to you quickly!