In hull transducer for Garmin

PMR#47

New member
Joined
Jul 6, 2023
Messages
4
Fluid Motion Model
C-26
Hull Identification Number
FMLT2535A323
Vessel Name
Blue Seas
MMSI Number
338477968
My Garmin depth finder is not functioning properly. Besides getting software updates I was told to add mineral oil to the in hull transducer. There are all types of mineral oil. Any recommendations? It also said I could use antifreeze (the pink type) Is that a good option? Please advise,
 
Before I fixed the leak in mine I used to just top it up with Volvo VCS coolant (yellow stuff), because that's what I had on board.

Any fluid should work as long as it's stable (i.e. won't allow any growth that would foul the sensor/reading)
 
Thanks for the quick response.
In my previous posts, I noted continual issue with the transducer on my originally new 2021 R-29. From delivery, there was a problem. The transducer cup was not attached to the hull by the factory and of course no fluid. The dealer installed and filled cup and transducer worked. 3.5 years later, 9 times refilling the cup at great inconvenience, the transducer does not operate more than 4 months. Garmin has been very helpful, but no permanent fix. Tried both RV antifreeze and mineral oil. Obviously, the assumption is that the fluid leaks from the cup, but no indication of escaped liquid. I have decided to replace the existing transducer cup. My research indicates that this is going to be difficult because the need to entirely remove the silicone sealant in a very limited area to gain access. BTW, Garmin recommends either 3M 5200 or Permatex Ultra Black silicone. Depends on how confident one is that the replacement will be a successful permanent fix. I am going with Permatex.
Lastly, you can test the transducer by putting it into a vinyl zip bag that is filled with water. Garmin recommendation. Good luck.
 
Also to add, to fix my leak I used an entire tube of the following. I made a donut with it, similar to how you would install a sink drain with plumbers putty, been holding fine for 4 months. Not sure if it's better or worse than 5200, but I think it's easier to work with as an almost solid putty.

 
Also to add, to fix my leak I used an entire tube of the following. I made a donut with it, similar to how you would install a sink drain with plumbers putty, been holding fine for 4 months. Not sure if it's better or worse than 5200, but I think it's easier to work with as an almost solid putty.

Interesting. I am told that in Florida, the high ambient temperature is the issue with sealants. Personally, I find that hard to believe. In any event, I would think that a Permatex product would be able to withstand intense heat. Or at least the heat in a bilge.
 
My Garmin depth finder is not functioning properly. Besides getting software updates I was told to add mineral oil to the in hull transducer. There are all types of mineral oil. Any recommendations? It also said I could use antifreeze (the pink type) Is that a good option? Please advise,
 
Did you get this resolved?

I think this belongs in the ask the factory area.
Others have used antifreeze. That is my plan on my boat.
 
Someone posted that there should be an o-ring to seal the transducer to the cup. With ours the factory seems to have relied on liberal amounts of grease. Does anyone know the size of o-ring or the model of the unit so I can enquire at Garmin?
 
If it helps, I think it is a GT15M-IH transducer. It comes with multiple tubes at different pitches to fit the slope of your hull. Each one has an o-ring. Maybe someone has a spare?

I just got mine fixed, using liberal amounts of 3m 4200 sealant. It worked for me.
 
On my 2018 C24 the factory install of my transducer came lose from the hull after about a year and I could tell it was a poor installation. I cleaned the cup well, sanded the hull, cleaned with acetone and used 4200 to attach to the hull. I have had no problems and have not needed antifreeze for 5 years now. I check it every year or so but have never need to add antifreeze. Any problems I have is probably the transducer it self. I put Vaseline on the original o ring.
 
On my 2018 C24 the factory install of my transducer came lose from the hull after about a year and I could tell it was a poor installation. I cleaned the cup well, sanded the hull, cleaned with acetone and used 4200 to attach to the hull. I have had no problems and have not needed antifreeze for 5 years now. I check it every year or so but have never need to add antifreeze. Any problems I have is probably the transducer it self. I put Vaseline on the original o ring.
Thanks for confirming that there should be am o-ring. Mine never had one, just grease.
 
If it helps, I think it is a GT15M-IH transducer. It comes with multiple tubes at different pitches to fit the slope of your hull. Each one has an o-ring. Maybe someone has a spare?

I just got mine fixed, using liberal amounts of 3m 4200 sealant. It worked for me.
Thanks! I’ll check with Garmin
 
On the 2022 R-31, the transducer is located below the refrigerator. Has anyone relocated the transducer to a more accessible location, such as below the V-berth?

I assume the existing location was picked as the optimal setup due to hull design?
 
my RT 31’s transducer is located in the stern, pull the rear seat forward for access.
 
We replaced the pink antifreeze in our R31-CB and our R21-EC. No more flashing or disappearing depth readings!
 
Sorry to bring this up again. In the posts above, there are mentions of the location of the transducer in 2 model years of rt-31. I have a 2019 rt-31. Can anybody trell me the location of the transducer in this model year? I asked the factory, but no response (frustrating).
Thanks in advance.
 
Sorry to bring this up again. In the posts above, there are mentions of the location of the transducer in 2 model years of rt-31. I have a 2019 rt-31. Can anybody trell me the location of the transducer in this model year? I asked the factory, but no response (frustrating).
Thanks in advance.
 
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