Looking for Anchor Watch App with External NMEA GPS over Wifi / TCP

kitling89

Active Member
Joined
11 Nov 2020
Messages
45
Location
Patagonia
Visit site
I have tried many of the popular anchor watch apps for android like Sail Grib AA and Anchor Lite / Pro. Both of these have a nice interface but the issue I have is they utilize the internal device GPS which is spotty at best on my steel boat.

The good news is I have a Digital Yacht AIS transponder that broadcasts external NEMA GPS data over a wifi network via TCP.

Does anyone know of an anchor watch app for Android that can utilize this external GPS data?

I have reached out to the app designers and Digital Yacht with little success.

Alternatively, maybe it is possible to spoof the device's internal GPS data with the NEMA source?

I have the external GPS over wifi and the tablet, just need some software to get this system into a reliable, low power, bedside system.
 
I may be wrong - however I would investigate if there are any apps that simply take the GPS data from the external source to the phone. The hope here would be that the external data took precedence over the internal.
 
In the absence of a bunch of replies I'll raise some possibilities which I'm not in the least bit sure of, but perhaps it's easier for people to correct me than post from scratch :)

Option 1: Find an anchor watch app which explicitly takes external GPS data. I've never used OpenCPN on Android nor used the anchor watch functionality but it (a) is available on andoid, (b) takes external data over a network and (c) has anchor watch functionality. There are lots of OpenCPN users on here so maybe someone could comment?

Option 2: I'm pretty hazy on this because I switched to an iphone a while back and it's a long time since I tried my hand at developing on android but your other option may be to enable developer options on your phone, switch on "mock locations" and find an app which will take GPS data from a network connection and use it to provide a "mock location" to your existing anchor watch app. The feature was intended for testing but I *think* (low degree of certainty and correction welcomed) it's a standard way of using an external GPS over bluetooth. Obviously you're talking about wifi rather than bluetooth but the principle is the same (although the availability of appropriate apps may be lower).
 
Thanks for the responses. I would prefer a stand alone app just to keep things simple but I will look into something like OpenCPN + plugins.

I have asked a few app developers including Henri at Sail Grib about spoofing a mock GPS location using wifi NEMA data. So far the only things we have found are development tools which are PC based. Overall this is a less reliable solution in my mind anyways.

It is strange to me that Digital Yacht has so many products that broadcast NEMA over wifi in one form or another, yet they don't have (or even know of) an app for this. Their competitors, Vesper Marine, have a very similar product that does include this app and as far as I am concerned it is a major selling point. Particularly if your goal is to relegate the chart plotter to a backup role.
 
I have tried many of the popular anchor watch apps for android like Sail Grib AA and Anchor Lite / Pro. Both of these have a nice interface but the issue I have is they utilize the internal device GPS which is spotty at best on my steel boat.

The good news is I have a Digital Yacht AIS transponder that broadcasts external NEMA GPS data over a wifi network via TCP.

Does anyone know of an anchor watch app for Android that can utilize this external GPS data?

I have reached out to the app designers and Digital Yacht with little success.

Alternatively, maybe it is possible to spoof the device's internal GPS data with the NEMA source?

I have the external GPS over wifi and the tablet, just need some software to get this system into a reliable, low power, bedside system.
open cpn works well in this need / mode.

there are 2 versions of android cpn, a free one which is well out of date and an official one that is quite reasonable. Also have DY Ais and boat based wifi. All works well, also in my steel boat, but i imagine it does depend where the wifi router is mounted.
 
The thing is that your situation - a smartphone that can‘t fix its position by GPS - is quite an unusual one.

Pete
The OP said 'Tablet'.
Alas, there are lots of tablets with no GPS.

Easiest thing might be a Garmin GPS?
You can't have too many standalone GPS units on the boat......
That's what our boat has, and with the external antenna it's accurate and saves worrying about running down the phone battery.

IT ought to be an easy DIY project?
Google 'raspberry pi GPS anchor alarm', it suggests others have done this.
 
I would prefer a stand alone app just to keep things simple but I will look into something like OpenCPN + plugins.
Opencpn will do what you want, though not quite as sophisticated as the anchor watch type apps. 2 choices, set a waypoint then in the menu turn set anchor watch, call it '50 m' and it rings alarm if boat is further than 50m from the mark, -50m rings if the boat is closer.

The track helps to drop the mark just where the anchor dropped.

Plus in opencpn you get one of the better ais displays around.

Though also on a steel boat, my phone runs anchor pro with it's internal gps fine on a bracket next to a window.
 
Last edited:
The thing is that your situation - a smartphone that can‘t fix its position by GPS - is quite an unusual one.

Pete
The tablet does have an internal GPS, it is just not nearly as accurate as the external GPS antenna - particularly when below decks in my steel hull.

It sounds like I will give OpenCPN a try. Thanks guys.
 
The thing is that your situation - a smartphone that can‘t fix its position by GPS - is quite an unusual one.

Pete
We have an aluminium hull and exactly the same problems, it may get a fix but it is not consistent enough to run all night without sounding the alarm at least a couple of times! Our old gps allowed for an external alarm sounded to be connected but the new one dosent so only has a weedy internal spindle.
 
Top