Depth Sounder Problem

trailertrawlerkismet

Well-known member
Joined
Feb 23, 2011
Messages
2,519
Fluid Motion Model
C-24 C
Vessel Name
(2022) Kismet
About once per year I’d have a problem with my Airmar P79 hull mounted dept sounder loosing the depth display on the Garmin GPS screen......the depth would flash and then nothing. With factory guidance I adjusted settings or added fluid to the transducer cup and all was good for about a year. On the most recent episode I was reading the instruction manual to figure out the proper amount of fluid to add and saw that there is supposed to be an O Ring slid up onto the base of the transducer. When checking mine it had no O Ring and therefore the reason the cup would loose fluid over time and cause the transducer to stop reading depth. The ORing is 60mm or 2.3622 inches in size for the inside dimension (id). I only mention this in the event others have a problem in the future. My guess is that the O Ring feel off at some point during one of my inspections.

Jim F
 
I posted the same issue several years ago. The factory forgot to install the o-ring. I have an extra o-ring cable tied to the cable for the transducer just in case the o-ring fails. I use a small a mount of Vaseline to lubricate the oring. I have not had an issue since installing the oring. I do change the propylene glycol every couple years and clean the inside of the cup.
 
Do you know what type of fluid is used?
I have a 2014 31CB and depth shown is not accurate Thanks
 
Water works, but it is recommended to use antifreeze. One, it won't freeze, and two, the pink color makes it easy to see if there is a leak.

I came off a big wave the other day, and knocked the cup loose. Had to take it off, clean off the old caulk and reinstall it. I'm hoping it will hold. Just used caulk, should I have used something else?
 
NEDBETTY":18k2yzjb said:
Do you know what type of fluid is used?
I have a 2014 31CB and depth shown is not accurate Thanks

Propylene Glycol/pink antifreeze as already mentioned; also, mineral oil works perfectly well and is what we use.
 
Personal, I don't care for the type that look though the hull. I use ether a transom mount or the thru hull type. No fluid to leak out and better return image.
 
I have a transom mount and have not found any turbulence issues other than the transducer being swiveled (canted) backward (great for backing up :lol: ) after encountering a lot of wave action that bounces the boat around. Also noticed that the Garmin in the boat depth sounder does not read the same as the outside Striker-Garmin. I have adjusted the offsets, but still not in agreement, so I set one for the keel offset and the other for the bottom :ugeek: .
 
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