Depth Sensor Adhesive

[davydub]

We've been slowly losing fluid level in the depth sensor housing for our RT27OB (2019). What is the best choice for the adhesive/sealant?

 

[sfladgard]

I just re-glued mine for the third time. I have tried Sikaflex 291, the original adhesive used by Ranger but had to go to 5200. Both have failed. This time I roughed up the base of the unit with a wire brush and went back to 291.

Good luck with yours

 

[Bosn Mate]

If it is an Airman P79, the installation instructions list Silicone sealant (such as GE® Silicone I or Silicone II). That is what I used and my leaking problem was solved!

Mike

 

[Cutwater28GG]

I used 4200. it has stayed put since reglueing on the cup.

you have to get the hull really clean before application. like sanding it down clean.

also note that the leak is far more likely coming from the crappy o ring install of the sensor in the cup. very common problem.

 

[Wee Venture]

+1 for 4200. That is what I used and so far it is working well. As already mentioned, check the o-ring first. Mine, however, was leaking at the bottom. As I pulled it up, all the caulking pulled right off the hull easily, while still firmly attached to the plastic cup base. I could see where it was moist underneath the caulk and had been seeping out. It looked like it had been sealed with black Sikaflex.
I sanded with 80 grit and scrubbed with acetone before reseating. Note that 3M recommends not using alcohol for cleaning as it interferes with the curing process.

John

 

[ixlr8]

On my 27OB I had the cup come loose from the hull. After sanding the hull with 80 grit I put it back down with 4200, two trips later it came loose again. Re-sanded the hull, cleaned up the cup and reglued with 5200. Several trips later... cup came loose again. Not just leaking, broke free from the hull in all cases. I then reglued it with a 2 part adhesive I 'borrowed' from Sabre Yachts where I was working at the time. No issues since. According to RT-Andrew, the cup should be sanded with 36 grit sandpaper. It should be very rough and not shiny smooth. It was obvious that the cup was not sanded rough before it was installed on my boat.

 

[jack_patricia]

Some may be having problems with 4200 because they missed the cautionary note that the hull surface should not be cleaned with alcohol. From 3M: "Alcohol will interfere with the curing process and extra care must be taken when using alcohol as a cleaning solvent to prevent any contact with the sealant." They also state that a primer may be necessary for full adhesion. It may be the main problem we have is FM's use of silicone sealant when mounting the barrel vs. the glycol mixture in its presence. FYI 4200 worked well for me but I did prep the surface thoroughly with Acetone.

 

[Cutwater28GG]

+1 to not using alcohol!