Transducers are a critical part of your fishfinder install - and - an incorrectly placed transducer can result in erratic or flat-out wrong readings on the fishfinder. So. If the fish finder isn't giving you the results you might expect, double-checking the installation of the transducer is a good first troubleshooting step.
Most sounders should automatically identify and run your transducer. Before you go changing all the settings, it would pay to check the plugs, wiring and placement of the transducer. Once it's going fairly well, settings can help hone in and optimise the setup.
This article is intended to give you some best practices regarding transducer placement. If unsure, we always suggest getting a professional to install the setup.
In short, you want to have the transducer placed in line or slightly below the line of the hull and clear of any turbulent water so it can have a clear path to reading sign.
If the transducer is placed higher, wash coming from the edge of the transom and the blowback from the prop can cause 'dirty water' that will mess with the results coming from the transducer. Having the transducer installed in line with the hull largely solves this issue.
However, it's also worth remembering that lifting stakes, chines, trim tabs, and pumps - can all cause turbulent water to wash over the transducer. Anywhere there are pressure zones, dirty water is created.
Transducers should be placed on the right, not the left side of the hull - because most props go clockwise and then push water off to the left. Even though the props are further back, they still cause a vortex, hence, muddy water.
The Angle of the Dangle
Flat or angled is no doubt an internet argument for the ages.
Try both. Many Kiwi Fishermen want to 'hunt' for fish - so often moving while seeking fish - a little 'forwards' angle can help with this. Start with it flat, and then try moving it forward a little.
So - where to place it?
A shortcut to finding a good starting point for placement is to head onto the water - get your mate to steer the boat in a straight line, stick your head over the back and look for clear water. Mark that point.
Install there, then head back out onto the water. Get your buddy to get up to cruising speed and make a slow right turn. This has the same effect as dropping your transducer. If your sounder report gets better - you need to move the transducer down. If it cleans up with a left turn, you should look to lift it back up.
There is a great read about sounders and transducers over here - https://www.lowrance.com/sonar-basics/
Transducer Placement - https://www.svb24.com/en/guide/how-to-find-and-install-the-right-transducer.html
Reading your sounder - https://www.fishing.net.nz/fishing-advice/how-to/reading-your-sounder-and-identifying-fish/