Depth Sounder Issue

Bob&Jilly

R27-OB Portland OR Lynnsanity II
Joined
Mar 13, 2025
Messages
64
Location
Fargher Lake WA
Fluid Motion Model
R-27 (Outboard)
Hull Identification Number
FMLT2757*818
Vessel Name
Lynnsanity II
The fluid on my depth sounder was replaced a couple of months ago and everything was fine until recently when I am getting negative readings and sometime it will go back to flashing normal depths. Any thoughts would be appreciated
 
It's leaking out. You need to re-glue the cup to hull to stop it from leaking fluid out.
Got it, have never done that before. Will need some instruction. I just unscrew the top and replace the antifreeze? Thanks
 
Last edited:
Got it, have never done that before. Will need some instruction. I just unscrew the top and replace the antifreeze? Thanks

Remove the 6 screws on the top of the transducer to remove the sounder… that leaves the cup which is glued to the hull. Wiggle it with your hand. It’ll probably fall off easily in your hand. This is why it's low on fluid (it's leaking out the bottom). Clean up the hull, clean up the cup. Re-glue it with like, 4200 sealant/adhesive. Let it dry. Fill it back up with RV Antifreeze, and put the sounder back in with the 6 screws. One key thing of importance… on the sounder, you will find a triangle.. that needs to point to the centerline of the boat (to starboard in this case), this is really important else the signal will shoot off the side of the boat instead of straight down, and could result in inaccurate depth readings.

Here's a photo of the transducer installed "backwards". If you zoom in, you'll see the triangle pointing to the port side, away from the keel. The triangle must point towards the keel, (to starboard in this case).

IMG_8074.jpeg
 
Yeah, I remember when I found all sorts of red liquid in the bilge. Had a mild heart attack.
 
For the 2nd time, mine quit working I opened the transducer, and there was barely any antifreeze in it. I filled it, and it is still not working. Assuming I need to buy a new transducer, has anyone relocated their transducer from under the refrigerator to a more accessible location?
 
For the 2nd time, mine quit working I opened the transducer, and there was barely any antifreeze in it. I filled it, and it is still not working. Assuming I need to buy a new transducer, has anyone relocated their transducer from under the refrigerator to a more accessible location?

You most likely don't need a new transducer. You most likely need to re-glue it to the hull as it's leaking fluid out the bottom cup that's glued to the hull. Sikaflex 291, or 4200 would be sufficient.
 
I refilled the transducer and I am still getting a flashing reading that goes to 0' after a few seconds. Checked the cup and full. But seeing this seems to be a yearly event I would like to relocate the transducer to an easier location for servicing in the future.
 
I have a 2018 C24 and I am having the same problem. I had to reattach my transducer 6 years ago and it’s been fine ever since until recently. Always full of antifreeze but seems to flash a depth more than usual weather going at idle speed, cruising speed or fast. It doesn’t go back to zero and I have always had problems going fast in certain kinds of seas because of air under the boat but hardly ever going slow. Wondering if a somewhat dirty hull could cause the problem. Anyone have any suggestions.
Ken Keir
C24
 
I can tell you my suggestion because I'm tire of the poor reading on my factory transducer. It doesn't work deeper than 40 feet or shallower than 6 feet (seems to become intermittent when I get down to about 5 feet, right when I need it to read accurately the most...and it's not the settings, I've tried everything).
I'm just going to bite the bullet and install an actual through-hull transducer so I get accurate reading and water temp too.
 
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