Garmin losing depth

[WalrusLike]

My Garmin 551S often looses its depth reading. At first I thought that once lost it needed a restart to get it again but now I know it does come back eventually.

The transducer is external on transom below water line and just in the water when on plane. The depth tends to be lost when in shallow water .5 to 2 meters type thing. It looses it when stationary or slow trolling or when on plane....

I don't think it's a positioning thing because it happens when stopped as well as sometimes on plane. I can't see a pattern apart from greater tendency when shallow irrespective of speed.

I suspect it's a settings thing. I've tried it on auto everything, dual or 50 or 200 hz. Bottom lock or not.... At one point it seemed more reliable on a manual range of 20 meters but I think that was coincidence.

Does anyone have any tips to try? It seems to happen when I most need it!

[Still_Dreamin]

Walruslike i have the same unit. Has happened a few times to me. The first time after i beached my boat to get some bait, just need to adjust angle of transducer. Think it must have bumped the bottom. Happened on the weekend this time half way across the bay in 13m just started flashing then about 1/2 mile later picked bottom up again .

[WalrusLike]

Yeah the first time it lost depth I found later the rear beaching had angled it upwards. But that was not the case in later incidents.

I will have another look tomorrow but I am sure it's angled level as it has been previously.

[WalrusLike]

Does anyone have any idea if the auto settings or manual ones are more likely to keep the depth reading?

[WalrusLike]

After some research it seems that the sounder looses depth mostly when transitioning from deeper to shallower water. Also sometimes on power on in shallow water.

I believe the Auto Gain is at fault. If I read it correctly the Gain helps when in really deep water or when trying to get lots of structure info. I have now just turned Gain off and early results seems promising.

[WalrusLike]

Another point I would make about this is that my reading suggests that with the 'gain' on high, the transducer pings and the sound comes back and then bounces of the hull, and then back to bottom, then back to transducer. The extra bounced signals confuse the sounder.

The thing about my boat is that it is a Baysport and they have a concave tunnel at the centerline. So a vee hull reflects sound away at an angle, a planning plank hull would reflect more than a vee, but a concave tunnel would concentrate sound like one of those parabolic microphone reflectors the spies and paparazzi use.

That's my hair brained theory anyway.

[Richo1]

Have the same problem in my tinny with that sounder. Thanks for the info will also try the gain function. Only have the problem when in shallow water or beaching.

[Lancair]

Ive had the same problem with 2 Garmin sounders now, a178C and now it happens with my 750s. In shallow water, the depth starts to flash, stays on the same reading it was regardless of the actual depth, ie: move into deeper water and nothing happens. The old 178C would sort itself out and start again after a minute or two in deeper water, the 750s needs to be turned off and on again to get it to work. Garmin have suggested I update the software in the 750s, but Im yet to do that.

[WalrusLike]

Rats.... Still got the problem. I am thinking now of updating the firmware. Will report if that fixes it.

[Fed]

Put up some pics of your transducer Wal.

[WalrusLike]

Thanks for the suggestion Fed.

The transducer is in the water even when on the plane. I really don't think it's that because apart from once when it was angled wrong, it seems fine at any speed in deeper water.

In shallow different story. Grand Marlin, who I respect enormously, thought it was a bit too high on the hull but as I say... It works fine in deeper waters.

Here is a pic:

[rosco1974]

looks a bit high to me as well,

[WalrusLike]

If it is in the water isn't that enough? Or does it need to be down a bit?

At rest it's at least 4 inches below the surface but it still can't get a depth if the water is shallow.

Not always... But sometimes.

[Darren Mc]

Hi WalrusLike,

I agree with the other guy's about the position of the transducer. I think it should be just about level with the hull so you get smooth clean water flowing over the surface of the transducer.
Apparently turbulance and air bubbles can interupt the signals. If this is a problem you can tilt the bottom trailing edge of the tranducer towards the front of the boat ever so slightly(only a small amount) to help with this problem.
But looking at the height of yours i don't know if the bottom edge of the hull would get in the way?

Buy the way i will be getting my new 2012 baysport 585 towards the end of this month. I'm looking forward to that.

[WalrusLike]

Thanks Darren for the input. I would agree with what you and the others are saying if the problem only occurred while moving.

But this happens even at the dock. At that time the td is well into the water and no bubbles or obstructions in its view.

So I think it's something other than positioning. I could be wrong. But should it work positioned there at rest at least 4 inches under the water and motor off?

Darren I bet time is going slow for you.....

Off topic: Can you find out if the sections to the outside of the centre well ( fuel tank sits in centre well) are foam filled? Just wondering.... Otherwise it's lost storage for long thin things.