Arduino based anchor watch

[goboatingnow]

I’m working on the software for my anchor watch system. The hardware is an Arduino mega plus lcd and a gps input. ( I may add a nmea2k interface later )

Id like some feedback on my methodology


The basic premise is this

There will be a push button at the wheel , at the designated anchor drop ( or shortly thereafter ) the button is pushed and the anchor watch system records the gps location

A subsequent push then records ( assuming you’ve dug in your anchor the max swing radius.

The system then monitors both the swing radius and the amount of swing angle ( these are adjustable ) ie if you fall out the max swing radius you get an alarm. If you swing through too much angle you also get an alarm.

I may add the ability to communicate this to my iPhone but again this is secondary.

Anything I’ve missed here. The gps uses SBAS to improve the accuracy

[TooCoys]

I have no idea, but take my money!!

[goboatingnow]

Originally Posted by TooCoys

I have no idea, but take my money!!

The code will be freely available !!

[goboatingnow]

The lcd will show a representation of the arrangement , with an anchor symbol at the centre a circle representing the max radius and a boat icon moving inside the maximum swing radius

The whole system is self contained so only it needs to be powered up.

[Bill O]

Software sounds very similar to the anchor watch feature in the opencpn Watch Dog plugin.

[goboatingnow]

Originally Posted by Bill O

Software sounds very similar to the anchor watch feature in the opencpn Watch Dog plugin.

Yes not dissimilar except all you need is a button at the helm. The instrument is positioned belowdecks.

The power is low around 100 mA average @ 12V

[Bill O]

Sounds fine. We wait for the anchor to settle in before setting our alarm/watch zone and we set ours down below. Not sure you need the button at the helm function, but could work for some.

[BillKny]

Sounds exactly like any one of dozens of apps available for Android or iPhone.

What’s the advantage of new hardware and connections at 10x the price?

[TooCoys]

Originally Posted by BillKny

Sounds exactly like any one of dozens of apps available for Android or iPhone.

What’s the advantage of new hardware and connections at 10x the price?

Two reasons.

1. Phones die. Batteries are drained depending on what apps you have running "in the background", and if your phone dies at 2am while you're on anchor, whats going to alert you at 4am when your dragging toward the rocks?

2. Service drops. If I have GPS issues with programs like Waze or Google Maps losing GPS connectivity, whats to say that it wont drop with any one of the dozen apps?

[BillKny]

Originally Posted by TooCoys

Two reasons.

1. Phones die. Batteries are drained depending on what apps you have running "in the background", and if your phone dies at 2am while you're on anchor, whats going to alert you at 4am when your dragging toward the rocks?

2. Service drops. If I have GPS issues with programs like Waze or Google Maps losing GPS connectivity, whats to say that it wont drop with any one of the dozen apps?

Two things wrong with your comments.

First, phones do not die if you have them plugged in to a charger. Kind of obvious, but you seem to have missed it. Just like your hardware needs to be plugged in to work.

For an anchor watch app NO data connection at all is required, just a gps signal.

So my question stands…

[Zanshin]

I've been programming Arduinos for years and wrote an anchor watch program a long time ago as a small project. I didn't have a piezo-alarm, but apart from that it wasn't difficult to write at all; although choosing an appropriate radius for valid swings at anchor wasn't as trivial as I thought. The Arduino actually uses less power than the GPS device (I used one from Sparkfun) and trying to optimize for power draw took up most of my time.

[Kelkara]

Mine works pretty well. When dropping the anchor, I'm on the bow with hands full of steel, not at the helm with a GPS, so I mark the anchor position while backing down setting the anchor, the position is set by specifying the bearing (look at the compass) and distance to the anchor (approximately the rode length). I can also adjust the anchor position by locating a point on the screen if it seems to be in the wrong place after swinging for a while. Then I set the alarm circle to a little over the rode length. It then maps the swinging pattern on the screen keeping track of the distance and bearing from the anchor point.

[goboatingnow]

Thanks folks

In my case there’s always somebody on the helm so the button there is sufficient

I currently use a phone based anchor alarm. But a built in one is simpler to use in the “ heat “ of anchoring with just a button press at the helm.

The hardware cost is a fraction of my iPhone cost ? , about €60 the vast majority being the GPS receiver. The Nmea2k option would let me use my 2K gps , which would reduce the hardware to about €10 !! ( and a 3D printed case ) but I’m not doing the nmea2k option first

Again the primary benefit is the easy setup , two button presses on the helm as you set the anchor

[goboatingnow]

Originally Posted by Kelkara

Mine works pretty well. When dropping the anchor, I'm on the bow with hands full of steel, not at the helm with a GPS, so I mark the anchor position while backing down setting the anchor, the position is set by specifying the bearing (look at the compass) and distance to the anchor (approximately the rode length). I can also adjust the anchor position by locating a point on the screen if it seems to be in the wrong place after swinging for a while. Then I set the alarm circle to a little over the rode length. It then maps the swinging pattern on the screen keeping track of the distance and bearing from the anchor point.

What’s the hardware ?

[Kelkara]

Originally Posted by goboatingnow

What’s the hardware ?

Arduino Mega with one of the common 3.5" touchscreen displays, a gps, a buzzer, and a plastic box.


The only real problem is that the screen doesn't have a pin to dim the backlight for night time, and I haven't added an option for a night-mode colour scheme. At the moment it sheds a bit too much light into the cabin at night.