Transducer repair/replacement

[CLC3]

I have an Airmar B744V in my 480 Sedan Bridge. The sonar stopped responding due to the well documented failure of the temperature component of the depth/speed/temp device. If just temp fails, Garmin MFDs do not recognize any of the transducer outputs. I really only care about depth - but I care about that a lot!

The speed/temp sensor is a replaceable insert. I purchased the replacement part and wired it in according to specs. My Garmin 8612xsv recognized the transducer so the replacement works at the electronics level if I can install it. The problem is removing the old speed/temp insert from the through-hull mount so the new one can be inserted. The old one is firmly stuck in place and (blush) in the process of trying to remove it, I broke off the tab at the top so there’s little to grab to try to pull it out. Options I am considering are:

1. Tap a screw into the top of the old speed/temp sensor to see if I use that to extract it
2. Haul the boat and try to strike the insert from the bottom to loosen and remove it
3. Install a complete, new replacement in-hull transducer as a possibly lesser cost alternative to hauling the boat and related repairs/services.
4. Some brilliant idea that the combined experience of this forum might suggest

Any experience or advice will be appreciated - I’m open to all options!

 

[pyro]

I just removed mine while on the hard. I was debating doing this in the water last year, or even beaching it and doing it while the tide was out, but opted not to. And it's a good thing because it was pretty hard to get out. I had to get a mallet and piece of wood to hit it from the bottom up. It's just an o-ring around a smooth plastic housing. Once out, it actually looked like it was in decent condition and I couldn't see any remants of salt or anything holding it in. I believe the instructions say to remove every year and lightly grease the o-ring.

Can you get a diver underneath with a block of wood and hammer? I've never swung a hammer under water - not sure how well that works. If you loosen it a little from underneath you can always have someone push it back down to re-seal it until you're ready for the final swap. I would still make sure the haul out option was available in an emergency!

 

[Dabble]

Haul out and do other maintenance is my vote.

 

[CLC3]

Haul out is certainly the safest and most certain approach and there's always "other maintenance"that can be done.

I have a diver available but I doubt that sufficient, controlled impact could be delivered under water.

It also occurs to me that I could treat this "stuck" condition with the transducer as I would any other on the boat... remove the cap, squirt in some WD-40 or other specialty lubricant, let it sit for a while and try again to extract the insert probably using a big screw in the top to get leverage to pull it out. The current speed/temp insert is dead anyway so "destructive removal" is not an issue. The new insert is wired, tested, working, and ready to put in place.