Garmin Depth display readout question

At times my Garmin data display for depth will flash on/off. There seems to be no good reason that I can fathom for it doing this. Sometimes the 456 feet will flash for example, sometimes 5.7 feet will flash when in fact I have 100s of feet underneath.

There was one time after running into a large wave the reading went from around 100s of feet to the flashing 5.7 feet.

Do others experience this I wonder?

The depth reading will always return to normal and sensible readings after a period of time that can be as much as an hour.

I get "Shallow Water" Alerts for no reason. I may be in the middle of the bay at 150 feet and it will flash 2.7 feet for a few seconds with the alarm. I have been trying to do some research on it. It may have something to do with the way the transponder is connected to the hull. This is the first time I have had a thru-the-hull transponder. I never had this problem on my other boats that had a stern mounted transponder.

I get this indication all the time at higher cruising speeds.
The flashing indicates that the transducer has not updated the display for some reason.
If you see the depth display flashing...slow down and it should stop flashing and update the display.
When I am at trolling speed the display is alway solid and updating.
When I speed up it will start flashing somwhere above 5 knots and seems to be affected depth, speed and trim of the boat.
The depth sounder on my sail boat also has a transducer mounted inside the hull and acts the same way.

Tony M
MollyM R-25 SC

Believe it flashes when it has lost "bottom lock" for some reason.

Charlie

Mine will do it at all speeds and even when I am at anchor. I spent the night on the hook a couple of weeks ago and had the anchor alarm turned on. About 2:00 AM the alarm went off. I got up and the alarm turned off before I could get to the chart plotter. I had a full moon and could tell the boat had not moved. I went back to bed and the alarm went off again. Again I got up an the alarm turned off before I could get to the Garmin. I decided to stay up and see what was going on. It was the Shallow Water Alarm that was going off. I have the alarm set for 3 feet and I was sitting in 9 feet of glassy water, and it was still going off. I turned the Shallow Water alarm off and was able to sleep the rest of the night.

By the way, I learned that the house battery will not make it through the night with both the chart plotter and the refrigerator turned on. I have a second set of house batteries and I am going to have to move one to the other set of house batteries.

I have had that same issue with my C-Dory 22 since I first began power boating. It is very disconcerting, especially if in a location that might possibly be getting shallow. Like others it mostly happens when I am traveling fast. I no longer have the alarm set but do watch the gauges carefully.

Hopefully someone will have a fix for us; meanwhile I will continue driving with an eye on various readings!

Anne Cox

I have yet to have a depth finder on ANY boat that was consistent. I consider them to be more for "trend" than exact depth. Speed, bottom contour/consistency, "stuff" in the water, water flow across the boat bottom, all seem to have some effect. I had a Garmin sounder/chartplotter on one of our sailboats, and it liked to give up when in less than 6' of depth... when you'd really like to know!

The Raymarine we currently have seems to be more consistent than others we've had (just wait, this means it will really be screwy when we get back to the boat), but I think the inconsistencies are just the nature of these beasts. I like the bottom depth contours on the e-charts as an "aid."

The cruiseboats I'm currently driving have Raymarine units that flash "last" with whatever depth it could last identify... seems to happen more in deep water (over 300') than in shallow.

Probably not the most helpful post ever, but just relating past experience.

Best wishes,
Jim B.

I've gotten the "flashing" twice; both times at really slow speeds. I knew I was in shoal water and was running at idle.

Once, it happened as I crossed over the crest of the shoal; I could see heavy weeds-figured the sounder was reading the weeds-they were probably lapping the bottom of the hull. The second time I was running in really murkey, shallow water and suspected there were weeds I couldn't see.

In both cases, my depth "reading" was never less than four feet. 🙂

Gene

There is a way to set the maximum depth on your display. If you touch the screen on the display and go to menu you can set the maximum reading depth. I have found that if set it too deep or shallow you will get the flashing. For instance, if the depth is 50 ft and the unit is set at a maximum of 30ft it will flash. On the other hand if it is set at 1000ft and the depth is 30ft it again will flash. I hope this helps.
Bob

The depth display on our Garmin (model 541S) fails in shallow water (less than 10 feet). It either flashes, freezes at some ridiculous number (usually 1.2 feet), or simply displays dashes. The in-hull (as distinct from through-hull)transducer was factory-mounted in our R-21EC. The factory glued-in a transducer that was actually intended to be mounted in a fancy, angle-adjustable holder with liquid inside. I questioned the factory, who assured me that their mounting worked better than the intended arrangment. The factory suggested that I contact Garmin for a replacement transducer, since the boat was new. Garmin sent me a new transducer, which was a different Air-Mar unit that was intended to be glued-in.

I installed the new transducer, and it works very marginally better than the original, which is to say that I still regard it as unsatisfactory. If the bottom is muddy, and especially if the mud has been churned up making the water cloudy, the depth function is certain to fail. It does not self-recover over any period of time that I am willing to wait, even after moving to deeper water.

The only "fix" that I have found is to turn the whole unit off and then on again when I know the water is deep enough and the bottom is hard sand.

I'd be willing to bet that Proffer's experiences with the intermittent shallow water alarm resulted from a large fish swimming beneath the boat. I had the same thing happen in a slip at South Seas Plantation. My alarm went off and the guage was reading 2' in a slip with 12' depth. I looked down and saw a large Manatee hanging out beneath the boat. Had similar experiences with a barracuda when anchored in the Dry Tortugas and a large shark in the Abacos. They like the shade.

If there are that many large fish under my hull, why can't I catch them? The thought had run across my mind that my problem might come from large fish, sea weed, or grass, but I have not "seen" them. I get the alarm a lot. I don't think I get that many large fish under my hull.

I get this frequently, and improve the readout by setting the gain on the depth sounder from automatic to manual then selecting maximum gain - this improves consistency of readings in most conditions.
In the sonar mode, push the menu button, and you will be able to adjust several settings, including the gain. WJC

Yup, lost the sonar depth for at least 20 minutes yesterday... No apparent reason... we were in water ranging from 22 feet to 0... Lost it when I went back to the dock so my son could go uptown and fetch a friend who wanted a ride... Backed out of the dock, turned the display on and no depth... Has happened before.... In my case it always seems to be when I am docked in shallow water, a foot or less under the keel... Really annoying!

I tested Paradox's suggestion today. The Gain on my sonar was set to Auto and was about 50%. I changed the Gain to Manual and bumped it up to 80%. I did not have one failure in three hours. I think that may have fixed the problem. I will keep monitoring it.

I also have tried setting the sonar gain manually, but my experience has not been as good as some other folks have reported. When my sonar fails to display properly, exploring the gain range manually restores operation less than 10% of the time. Sonar failures occur in shallow water (less than 10 feet), especially when the bottom is soft or muddy. Sometimes the sonar will not acquire a reading even in deeper water (~ 15 feet) if the mud has been churned up to make the water murky. Sonar operation is fine in water deeper than 10 feet if the bottom is hard sand.

I offer two possible explanations as questions to see if anyone has explored these avenues:

1) In "difficult" conditions as above, could it be that a tranducer that shoots through the hull is inadequate? Has anyone tried replacing the tranducer with one that is installed in a hole through the hull so that no fiberglass is in the way? Any difference in performance?

2) Could Garmin's software for sonar signal acquisition and tracking be inadequate for these conditions? Does anyone know if upgrades are available? (Note that I discussed the problem with Garmin some months ago, and their only suggestion was trying a different transducer, which has not fixed the problem.)

I have exactly the same problem with my Raymarine sounder and I believe the problem is caused by the location of the transducer. I believe it should be located closer to the centre of the boat approximately near the front of the engine and about 2 ft out from the keel line. I have been told by the local Raymarine expert that a thru the hull transducer gives better results than an in hull transducer but personally I have not checked it out. The Raymarine people are sending me a test transducer that I can put over the side of the boat and see if the problem is fixed. I will do these tests next week

I have the same problem still, that is the depth reading sometimes gyrating wildly and then flashing. I am still wondering why this flashing and very inaccurate depth reading cannot be resolved.

Last week while in shallow water my chart plotter was showing 25.5 feet. Another Tugnut was seeing 5 ft on his, I learned later.
I do not believe it is connected to something like the keel offset since there is such a large difference in stated depth. I understand from Bob Ostlund's earlier post that he resets the depth reading amount to a much smaller percentage, such as showing the maximum reading to be 100 or 200 feet it reads more accurately. Do others reset their maximum depth for more accurate readings?

That seems to work for him; however if a number of us have false readings in shallow water that can take quite a bit of time to self-correct, that is not satisfactory for me. Surely this can be more reliable, right?

Does anyone have new insights? (My depth sounder is mounted inside so is not thru-hull.)

Thanks in advance...

I don't really care about depth readings that show 100s of feet below me. What I do care about is the depth displayed when in shallow waters.

FYI...
I'm not at my boat at this time so cannot say what my Garmin's depth configuration is set at... but I've not found issues when in shallow waters especially when the water is clear enough for me to see the sea bed. I always monitor the shallow water depth readings as I leave and enter my marina as I can see the sea bed clearly... and the depth reading being displayed is IMO telling me the truth.

Probably unrelated but our depth readout started flashing 4.5 ft consistently on a recent trip. We were also getting errors on the autopilot dash display while the remote would still work. We suspected garmin network problem/glitch and tried the usual unplug/reseat drills... in the end a factory reset on our 5212 cured the maladies. So far.

The Garmin network is usually pretty robust but it is not without problems. in some installs the sonar transducer does not go directly to the chart plotter, rather it goes to the network "router" box first where it travels within the matrix to the dash where it splits back out to get to the chart plotter.