No Depth Reading - Airmar P79 Transducer Issue

[Happy Place]

2014 R31 CB....my transducer is mounted near the stern on the starboard side.....super fun to access :-(

From what I read here, getting no Depth Reading might mean that I needed to add glycol. When I got my hands on the transducer, the top came off easily, as did the unit itself...it just pulled away from the hull. The unit itself is sealed and based on my research, is supposed to sit in a barrel attached to the hull which is filled with glycol but....I do not have that barrel/ reservoir....it (was) just attached to the hull with what looks like the remnants of some old caulk to secure it down.

My question is this: I have been getting good readings for the 3 years I've owned her so should I just clean the area and re-install the transducer against the hull with some new caulk to hold it on place OR should I source the mounting kit and install it that way.

Finally....is there any other reason that I would not be getting a Depth Reading?

 

[Cutwater28GG]

if it was glued directly, the glue can crack and it will not work.

I had this issue

viewtopic.php?f=5&t=10919&hilit=transducer

 

[Happy Place]

Thanks for the information! My transducer has pulled away from the hull and I need to reattach it. Wondering what sort of glue/ epoxy I should use.....

It appears to me that there is no glue between the transducer and the hull, just a bead to epoxy around the outside of the unit itself.

 

[jeffhowell1]

Airmar P79 transducer should be mounted in housing and filled with antifreeze, not sure why this wasn't done... very strange

Here are installation instructions from Airmar:
https://d3fyi2ud8f6h0p.cloudfront.net/u ... 1-15-1.pdf

Many previous threads on Tugnuts about these working intermittently, recommendations in this case is to reseal housing to inside of hull and make sure housing is full of anti-freeze.

Last Fall I gave up on mine and had thru-hull transducer (Airmar B619 w/Garmin 8-pin connector) installed, port side next to diesel engine, opposite of water intake. Works fantastic, reads down to 1000', never loses bottom reading, also tells water temp.

 

[Cutwater28GG]

It’s faster And the cups are known to leak.

I used 4200. In case I ever needed to get it off again.

 

[gswearin]

Hi All,
I'm tackling filling the transducer on my Garmin GT15M. it may be in the numerous posts on this, but anyone know the O-ring size? I'd like to be prepared if it needs replacement.
Also, tips on getting all the screws out? For the back half there's only about 2" of clearance. Thanks.

 

[jack_patricia]

Gary, if you don't have enough space above the barrel to use a stubby screwdriver - it's probably a #1 (smaller sharper head) size for those small screws - you should buy a small ratcheting 90 degree screwdriver. Most jobs won't require it but for some it's indispensable....and it's very affordable. It's unlikely you will need a new o-ring. Like Cutwarer288GG, I used 4200. Remember that, if like me you are in a hot climate, you don't want the fast cure 4200. Why FM continues to use silicone sealant when mounting the fathometer barrels has mystified me. Look at all the fathometer failures on this forum that are actually sealant failures.