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Today I’m Garmin Grumpy

Garmin GPSMAP 721xs
Garmin GPSMAP 721xs - does yours overheat as well?

For years I’ve helped out my dad with Chart-plotters for his sail boat in Scandinavia. He has been a huge Garmin fan due to the auto routing. (Garmin Auto Guidance)

Garmin GPSMAP 541

He started out with a ? 541 GPS map series on his boat and that got him hooked. So I have helped him upgrade thoughout the years. The GPSMAP 541 worked perfectly until decommissioned.

After the GPSMAP 541 we updated him to the new “Touchscreen” Garmin GPSMAP 720. He absolutely loved it. It is not mounted “in” the boat but sitting nicely on its stand just below the spray hood. So usually shaded and protected from the environment with maximum potential airflow.

Garmin GPSMAP 720 overheated

Garmin GPSMAP Heat Issues

But after 3-4 years the 720 started to have issues. It would simply hang when it got hot. During the season it got worse and worse and less and less environmental temperature was required for it to hang. We tried everything from software updates to factory resets – but nothing helped at all.

So I hunted high and low – and found him a Garmin GPSMAP 721xs.

And now the Garmin 721xs overheats

He put that in about 4 years ago. It has performed flawlessly…. until last year where it started doing exactly what the old 720 used to do. It would hang and then a power “reset” would bring it back. We again tried everything from software updates to factory resets and nothing changes.

Back to Paper Charts

Now he is on sailing vacation – and the 721xs has become absolutely impossible to use. When it gets warm – touch screen stops working and performance becomes “intermittent” – with frequent “hangs” requiring a full power reset. So he is back with paper charts for navigation. And this is in Scandinavia – not really know for high summer temperatures.

So now you know why I’m Garmin Grumpy today.

My theoretical speculation

I think the heat transfer inside the unit fails over time. There are heatsinks on the main processors that transfer heat to the outside of casing. To connect the processors to the heat sink you use a heat transfer material like heatsink paste or pads.

Paper Charts

I think the heatsink paste or pads Garmin put between the “surfaces” dries out over time leading to fatal overheat of the devices.

Since it was a problem already on the Garmin 720 – Garmin should have been aware and done better for the Garmin 721xs – but it seems like Garmin has not learned. Garmin GPSMAP’s has ALWAYS been very hot devices no matter which devices in the modern range I’ve had my hands on.

But I’ve asked my dad to ship the Garmin GPSMAP 721xs to me and I’ll take it apart to figure why it is failing. But I do think I’m on the right track….

But let me know in the comments if you have had similar issues with Garmin GPSMAP units.


  1. Had a 720s touch screen and it was not the greatest, asked the dealer for a upgrade garmin unit Not touch screen, buttons, told him my 720s gripes, he assured me they were all sorted out in the design and development of the 721xs and that it was bulletproof. My arm was twisted as the honey was poured into my ear… I mean who doesn’t like a touch screen… 6 years later the 721xs screen is #*@%%# and I am mad as hell. 7000 nautical miles and hundreds of fishig spots gathered over that time, calculate the value of 7000miles, towing travel and accommodation to seaside towns etc etc etc.
    I have been told that the 721xs is discontinued here is South Africa that there aren’t replacement screens, as the screens alone cost more than a new unit (how people can believe this crap)
    We would be so much better off if garmin told us that when u buy their units they have an expiry date. They simply require you to pay top dollor to borrow their units for a few years and then buy another one.
    I’m going brand hopping.

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