I posted a question about this 4 years ago.
The post is "Too Old to Repost"
Just wondering if there has been any development in off course alarms . This is especially when a solo sailor takes a nap under windvane pilotage and the vessel veers off course slowly with a wind direction change.
Here is the original post.
gary
www.seabreeze.com.au/forums/Sailing/General/Is-there-an-app-?page=1
How about one of these, assuming you have a device like Chart Plotter etc that outputs NMEA 0183 data. It works with Trek Transponders NMEA 0183 if you have one.
www.amisales.com.au/sku-1570510-md76-heading-mon-off-course-alarm.html
Now that's a nice bit of professional kit!
Ok Gary, This looked like an interesting little app so I speced it out and have been hacking code for the last few days. I'm close but wanted to confirm a few things while I'm tweaking the interface. Nothing that is critical, just wanted to verify and let you know I may have something for you to try soon.
1. min off course angle ( and max ) 5-60 steps of 5
2. check frequency, I'm thinking minutes here not seconds, say 5 min min in steps up to a max of 1hr
The thing is while you can check every few milisec, given that you are looking for something over 10nm or so thats a 2 hr trip at 5kts so checking every 5 min or so seems reasonable to me.
I'm coding in Html/Javascript to run in a browser window. You can either get the html file from a trusted website or launch it directly fom your phone/tablet. ( simpler than building an app that has to be side loaded as I don't contribute to the app stores ).
HI D1
That sounds way above my head.
I found an app that has a off course function, but it has so many options loaded onto it that I could not figure out how to set the course and the alarm.
Too many bells and whistle is not better,
The app is called Sail Expert.
Gary
Gary - iphone or android? This is important because I'm going to buy an android tablet today for OpenCPN.
This would be useful for people running older and less reliable autopilots too, particularly anything involving a fluxgate compass.
Hi JonE
i use Android
On (Super cheap Chinese) Tablet for Navionics and CMaps.
On phone for Boat Speed app. (Which I love)
Gary
Check BOAT SPEED JON.
I paid the $1.
The font is huge, a night light setting and an audio announcement of speed.
You can leave the tablet below and get a speed reading (audio) as often as you want.
That is until you get sick of it and switch it off for ever.
I love my tablet, but be warned they are not really Moisture proof let alone waterproof.
They will slide off the table in the blink of an eye and you can't really read them in sunlight.
Other than that. Great
Gary
Boat speed looks great, very polished.
I'm so close to being finished I will keep going anyway. 
You'll get my dollar D1
That looks great
Will the alarm be John Cleese vocal.
"Now. Just where do you think you are going?"
Gary
I think a more important alarm would be a cross track error alarm which would sound when your boat strays from the desired route by a set amount. That way any side current or leeway etc could be attended to when the alarm sounds.
My old school Garmin has that alarm feature which I set when windvane steering.
I think the use-case here is the one where there is no active waypoint, and certainly no integrated plotter and autopilot/course computer.
this probably isn't uncommon since all the modern plotters have abandoned NMEA0183 so installing a chart plotter involves replacing all your wind/depth etc.
at the same time everyone has a mobile phone or tablet and navionics so you know what direction you want to point in, you just have to set the wind vane / autopilot yourself.
Hi Ambler. RE; My old school Garmin has that alarm feature which I set when windvane steering.
That is the point Ambler.
Garmin have had this feature for 20 years or more.
Garmin bought Navionics and did almost no upgrades, so us with Navionics have to go somewhere else for a feature that should be standard.
I mean my car has alarms for everything!
Hi Jon RE; at the same time everyone has a mobile phone or tablet and navionics so you know what direction you want to point in, you just have to set the wind vane / autopilot yourself.
The point that I was making was when you are alseep under windvane, the boat can slowly change course with a windshift.
A simple alarm that sounds after you are 15 degrees off course or 5 degrees off course for 5 minutes would be great,
Nothing fancy.
Gary
Ok Gary,
Have a look at this. Been done for a while but a few little formatting things are not quite right. It uses the phone gps and I have found that the initial fixes are often quite inaccurate, not sure how to get around this.
rawcdn.githack.com/dna0xff/recipes/master/testOffcourse.html
Happy for feedback and comments and please treat it as a work in progress. I have tested the algorithms in all hemispheres and course quadrants but not on any boundary situations like sailing across the antimeridian or the equator.
It's a single file browser application so all there to look at how it works if you are interested.
Hi D1
I had been listening to Supertramp so I had headphones on.
When the alarm went off I thought that I was in the engine room of a nuclear submarine.
"What the hell, a radiation leak."
Sure got my attention.
Then the scramble to find the CANCEL button.
RESET did the job.
10/10 for an alarm that is impossible to ignore.
Will keep playing.
Thanks so much for the effort.
Gary
he he, and that was at quite a low volume. It's a bit of an easter egg. next update I'll let you change the audio.
I don't think this should have a mute or low volume setting.
That could lead to a deadly mistake down the line.
On and LOUD is the best.
gary
Actually, the alarm on my Smartphone clock starts at a medium volume and gets louder.
That could be an option.
If a concern is waking a sleeping crew member, the phone would be in the watchkeeper's pocket wouldn't it.
gary
