Sorry was out of town for a few days. Fist I have never done this for a fish finder. I have done it for inspeciton on steel. I would recommend the slow cure if your not going to use the clear silicone. The slow cure will hopefully allow any bubbles to rise to the surface. I would make a small wood or plastic frame (box) to hold in the epoxy. Make sure your surface of the boat is clean as you can get it with no old paint, blisters or anything like that. You need a clean and sound surface. Then put the frame where you want to install the TD then fill it slowly. When mixing the epoxy be careful as you can to not mix bubbles in to the mix. Some are almost unavoidable. Once you have it filled almost to the top slowly place your transducer in the mix. Remember also that you only need to have the bottom of your transducer bonded to the boat your not encasing the thing so don't need to fill the form all the way up, only enough to make sure you have a good surface coverage with the bottom of your TD and the bottom of your boat. Don't over think it ha ha I am sure you will be fine. PS you can leave the frame as it will not hurt anything.

