Depth finder/transducer issue

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    Have a newish 34ft NT (built 2020) and on the last couple of outings the depth display has been erratic. It shows depth at dock but once out of the marina it goes to zero for extended periods and then pops up with the depth (seems accurate to chart measurements) then goes out again to zero, etc., etc.  Speed or depth doesn’t seem to be a factor, as it goes in an out of displaying depth in all conditions.  Have checked the connection to the transducer and it seems ok. The chart plotter is Garmin 8612 and the transducer is an Airmar, B60-12.  the vessel is berthed on Bainbridge island.  Few questions:

    1. Any recommendations on trouble shooting or ideas on possible cause?

    2. Any recommendations on a local professional to have take a look at it if I can’t find/resolve the problem?

    3. Rookie question – if the transponder is the point of failure, does a replacement require the boat out of the water?

    Many thanks, it just is not fun to boat with a bum depth display!


    Gary White

    A couple questions. First, does it go in and out when you are not moving? If you are out on the water and it begins to be erratic, try stopping the boat and see if it recovers.

    Is it mounted on the Stern or is it a thru hull?

    If it is not failing while you are sitting still it may be that you are  getting air around the transducer which is interrupting its signal.  (Cavitation ). This is especially common on Stern mounted transducers if they’re not mounted correctly I.e. they are  too high or too low.

    If you find that the problem is the transducer and it is a thru hull mount then you will most likely have to haul the boat to replace the transducer.

    I hope that helps a little.


    Mike Young

    Mike, I see that Gary White has already shared some suggestions. I passed your post on to Larry Schildwachter, head of Emerald Harbor Marine in Seattle. Larry & his crew have done well by us & our boats over almost 20 years (including our current Nordic Tug 42). He was kind enough to share several ideas. Please keep in mind that he hasn’t been aboard your boat to check this out and I’m just giving you his top-of-the-head thoughts without any obligation on you or on Larry:

    “We can try and help. If the transducer is actually bad, then the vessel will need to be hauled. Have them try the sounder with the engine off and see if it still fails. Could be RF stray noise. Could be a bad transducer. Could be connectivity. Ask them if all their Garmin devices have been updated with the most current revisions.”

    Larry’s “engine off” idea may sound just like Gary’s “stop the boat” idea, but it isn’t. Each of these ideas could help you troubleshoot, but they’re aimed at identifying different potential problems.

    In case you do want to get Larry’s help, this is his contact information: 206-793-7950 (cell), Again, Larry understands that you haven’t hired him – I’m just trying to help you out.

    • This reply was modified 1 year, 5 months ago by Mike Young.
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