I need your help badly.  I am a professional musician, and am really bad at this stuff.  I am trying to mount my transducer on the inside of my kayak.  I lightly sanded the spot, applied a marble sized amount of the suggested adhesive (3M 5200), and put a weight on it so it wouldn't move.  Went out to the lake today, and it didn't work.  I got home, was worried about how I was going to get this thing off the kayak.  I pulled it right off...

There was only a very thin layer of the stuff, and it peeled right off the transducer.

So, what did I do wrong?  I'm dying to get on the water and use my depth finder!!

Three possibilites, the hull of the boat has a lot of air in the contruction and/or you used a flexible adhesive that absorbs the transducer vibrations instead of the proper adhesive (slow cure epoxy).

The third possibility is your kayak, what type do you have and exactly where did you mount the transducer and did the location have direct contact with the water?

I would guess it might be absorbing...the stuff seemed really soft.

It's a predetor K111.  I had it pretty much in the middle, but off to the side a bit, as it has a small keel. (I think that's the right word.)

I'm thinking that 3M 5200 is not as good as I was told.  Marine goop is being suggested by quite a few.  I guess I'll find some of that.

I'm not familiar with marine goop so I don't have a direct opinion on it. If it is flexible, it cannot produce accurate depth readings or may not allow small details to be displayed. The hull has to vibrate at the same frequency as the transducer and not have air between the transducer and hull, have air in the hull material, or have a substance attaching it to the hull that is flexible.

Some sit-in owners may have a proper operating system to suggest.

The most successful Sonar installations I have seen or heard of are done on the sit-on-top models that have open holes thru them that are used for the transducer mounting, allowing for direct water contact.

Use a 2 part mix epoxy to attach the transducer.  Get the slow cure kind for best results.

Use a 2 part mix epoxy to attach the transducer. Get the slow cure kind for best results.

X2, and if you stir it to mix it do it slowly to keep from adding air bubbles to it.

Before you epoxy it in place, make sure you find a place that it will work.  To do this, make a bowl in the bottom a couple of inches high with some clay, add some water and sit the Xducer in it so it's sitting flat on the bottom and try it.  If it works, and is in the spot you want, epoxy it down.  I use Marine-Tex but you can probably use JB Weld, that's a lot cheaper and easier to find locally than Marine-Tex

Slow cure epoxy is not going to work on a flexible hull. Go to Kayakbassfishing.com and do a serch...many, many guys have transducers permanently attached using Goop or Lexel, they will stay stuck to the "tupperware" boats.