Searanger sr260 tranducer? Which up or down.

Boat is a 20 ski boat. The transducer doesn't have an up or down arrow and instructions dont explain. One side is hard plastic and other side like a gel/glue side and concave. I assume the hard side but it has a line down that center that allows it to rock but ever so slightly. Will the adhesive i use allow for the small line on it? The wire comes out the side and says radarsonic on it. Pics are from ebay. the transducer is similar other than wire comes out the side not top or bottom.

Also this is a 4.3 inboard merc. the old transducer was glued on just below front of engine. I plan on putting in same cleaned up location. Boat is not in the water and holding it there i get no reading. Display says 0.0. If i put in a bucket of water and just let it dangle i can get a reading.

Any help or suggestions will be greatly appreciated! I've thought of just taking it out and gluing it down out in the water.

not the best picture to post....based on your description, I'd say you have a "trolling motor mount" transducer....the concave bevel is shaped to match to motor housing on a trolling motor, so it goes up....many have slots at the 'top of the ears' for a hose clamp to secure to a motor....

If you take your "setup" to a pool (instead of the bucket of water), it should be pretty easy to verify this...

This is not the one but similar. the wire comes out the side. No way to attach to a trolling motor. Mine doesnt have the lip like this on the top butthat is where i say it is concave.