ive always fished from canoes or rental jon boats without a fish finder and always targeted shallow visible structure/cover. i plan on buying a boat this year and want to fish deeper water. please bear with me for a dumb question.

the fishfinder shoots down a cone to read depth and structure. the screen (on most units) is two dimensional. what exactly are you looking at on the screen? how can you tell if the brush pile is directly under your boat or to the left or right of you? i hope that makes sense. will the manual that comes with the unit explain this?

i assume the left side of the screen is in front of you, the middle is below you and the right is behind you. im confused about the left to right view...

thanks

-z

you can tilt your transducer a little left or right and know everthing is that side.

Garnet

When you look at your screen it will be moving from right to left. The very far right side is your instaneous reading directly underneath your transducer. The best way to look at it is everything on the screen is in the past unless you are sitting perfectly still. So for instance if your driving and you go over a stump your unit will graph it as it goes under your boat on the right side of the screen. As soon as your past the stump the unit will start graphing the bottom again and the little stump-like lump on the screen will continue to move to the left until it goes off the left side. So if your using your trolling motor and your transducer is on the very back of your boat and you see a stump in the middle of your screen you could safely assume that the stump is several feet behind your boat opposite of the direction of your travel.

As far as the left and right side of the cone goes, it is very hard to tell what side of the boat something may be on. For a beginner its safe to say just think of it as all directly beneath you and don't worry about left to right until you get the rest down pat. Somoeone else here may be better at explaining that part.

looks like i was very wrong about how they worked. thanks guys, i'll try to find some articles online and learn more.

I found this video and hopefully it'll help you better understand how to read the graph. The right side of the screen is what is directly beneith your transducer right now. The left side of the screen doesn't change and is behind your boat that you have already passed by. So the further to the left is further behind your boat. I hope this helps.

Also this is a basic picture to help understand the picture on the screen.

Okay, theres more to the equation. The sound waves coming off the transducer are moving in a conical pattern. They stretch out farther laterally the farther down they go (ie the cone gets bigger). When the sound waves hit the bottom or a solid object they bounce back up and the cone continues to expand. In 100 feet of water, the sound travels 200 feet, 100 down and 100 back up. The sound that hits the surface on the return trip is covering a huge area, and the transducer gets a small return sample, not the whole thing. So it doesn't detect objects to the side of the boat very well. Maybe this will be some food for thought.