I bought a humminbird helix 12 gen3 last year and I’m having an issue with the side imaging. The right only reads about 30ft or so and the rest is black. It’s like this no matter what depth I am in. Does anybody know how to fix this? I am assuming there’s a problem with the transducer. The image does not show it well but I get much more range in the left side than the right.

Is your transducer mounted level. If it isn’t, it’ll read way “off”, and not be able to see certain areas. Should be level both side to side as well as front to back. And by level, I mean level with the lake bottom, not the boat hull. This can be different with every boat, depending on how it sits in the water at the speed you’ll be mostly traveling when scanning.  

Might want to try a factory reset to see if it will fix it....

Is the transducer mounted on the left or the right side of the boat ?  Is there anything blocking the sight of the transducer: livewell screen, bottom of the motor, another transducer …?

Your’s looks similar to mine last year. My transducer was bad and ended up having to get a new one. I’m not saying yours is because your image goes out quite a bit further than mine did. Your’s could quite possibly be an alignment issue. 
 

3 hours ago, Reel said:

Is the transducer mounted on the left or the right side of the boat ?  Is there anything blocking the sight of the transducer: livewell screen, bottom of the motor, another transducer …?

It’s an all electric boat, so I got it mounted on the trolling motor. I’m definitely going to realign it and see if it makes a difference.

Mine was doing the same thing. Wasn't level - side that wasn't getting much distant was pointed down just a little.