Forums > Sailing General

Off course warning app.

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Created by garymalmgren A week ago, 29 Jan 2025
garymalmgren
1234 posts
29 Jan 2025 8:04AM
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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

JonE
VIC, 338 posts
29 Jan 2025 11:10AM
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Gary - do you need it on an Ios or Android device?

Trek
NSW, 1165 posts
29 Jan 2025 12:29PM
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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

DrogueOne
207 posts
Sunday , 2 Feb 2025 9:25PM
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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 ).

garymalmgren
1234 posts
Monday , 3 Feb 2025 8:22AM
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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

JonE
VIC, 338 posts
Monday , 3 Feb 2025 12:44PM
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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.

garymalmgren
1234 posts
Monday , 3 Feb 2025 12:04PM
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Hi JonE
i use Android
On (Super cheap Chinese) Tablet for Navionics and CMaps.
On phone for Boat Speed app. (Which I love)

Gary

JonE
VIC, 338 posts
Monday , 3 Feb 2025 3:08PM
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Thanks Gary,

I have a shiny new Galaxy tab on my desk. Watch this space :)

DrogueOne
207 posts
Monday , 3 Feb 2025 1:58PM
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I have a few days head start on you!

garymalmgren
1234 posts
Monday , 3 Feb 2025 2:29PM
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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

DrogueOne
207 posts
Monday , 3 Feb 2025 2:40PM
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Boat speed looks great, very polished.
I'm so close to being finished I will keep going anyway.






garymalmgren
1234 posts
Monday , 3 Feb 2025 3:39PM
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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

Ambler
TAS, 98 posts
Tuesday , 4 Feb 2025 8:15AM
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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.

JonE
VIC, 338 posts
Tuesday , 4 Feb 2025 8:35AM
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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.

garymalmgren
1234 posts
Tuesday , 4 Feb 2025 6:35AM
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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



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"Off course warning app." started by garymalmgren