Setting Up a Fishing Kayak (Part III)
  |  First Published: July 2009

At first glance, installing a fish finder on a kayak might seem a little extravagant but let’s face it: for all the advantages kayaks have as fishing craft, the one thing they don’t do well is get you from one spot to the next quickly if things are slow.

Successful yak fishers live and die by choosing the right fish and location to target on the day. A fish finder tells you all about local bottom structure, can see schooling fish around your kayak in different depths and ultimately saves you valuable fishing time.

Choosing the right fish finder for a kayak is no different from choosing one for a boat. The makes, models and price ranges are endless but the good news is that we have never seen one that won’t work on a kayak with the standard transducer that comes out of the box. I also like a lot of the combo GPS units so I can mark my best spots on the sounder and it’s all contained in one unit.

To finish the install, you will also need a battery, power connections and preferably a RAM mount.

Transducer Placement

There are two transducer mounting methods to choose from: internal or external mounting.

My favourite is an internal mount where the transducer is glued to the inside of the hull. It sends and receives signals through the kayak skin; it loses some sensitivity but is completely protected from snagging weed or potential damage by snags or rocks.

To mount internally we cut out a piece of foam rubber (gym mat is good) about 20mm thick to a size of 150mm x 100mm. Then with a pen, trace out the shape of the transducer in the middle and cut it out. The result is a foam cradle for the transducer to nestle into. The foam is then glued down first with silicone. Position it inside the hull along the keel line in a reasonably central location and facing forwards. For those with Hobie pedal kayaks, the Mirage Drive doesn’t seem to affect performance so don’t be concerned.

Roughing up the area first with sandpaper will help it bond to the hull. Now fill the cut-out with a liberal amount of silicone and nestle the transducer into it, being careful to avoid bubbles which will affect the quality of signal.

Polyethylene kayak hulls are non-stick, like Teflon, so your transducer might need to be reglued each year. Common, cheap, invasive silicone like All Clear works best and holds longest to the hulls; expensive sealants are usually designed to be easier to remove and so won’t stick down as long in your yak.

An externally-mounted transducer will give a slightly improved signal but is not as neat. In the case of a few sounders, like the Humminbird 797 Side Imager, this is the only way to do it. Most transom-mount fittings that come with sounders will not be suitable for a tapered kayak stern so I usually opt for mounting on the rudder. The supplied brackets will still need some modifying but with some stainless ones it could be as simple as just doing some careful bending.

A transducer mounted on the trailing edge of a rudder blade performs surprisingly well as long as the kayak doesn’t need excessive rudder movement to hold course. It is also protected from damage by the front of the rudder blade if it comes into contact with an immovable object.

I have also seen transducers successfully mounted to the side of hulls on the end of PVC tubing that bends up and over to plug into a rear rod holder socket, thus making it removable.


Your fish finder mounting base will be unlikely to fit the kayak in any useful position so use a RAM mount to prop the sounder unit up. They give the unit some elevation away from splash, plenty of position adjustment due to the universal ball mounts and make the sounder easy to remove between uses.

Where to mount the actual unit on the kayak comes down to personal preference but there are three standard positions that work.

The front of the cockpit on the deck is obvious – it’s easy to see and out of the way. Don’t worry about having to lean forward out of the seat to get to the buttons, once the sounder functions are adjusted to your settings it only ever needs to be turned on or off.

For the Hobies, RAM make a fantastic 1” ball mount that wedges into the mast base so no holes need to be drilled for fittings.

The side of the cockpit on a pedal kayak is great for combo units as it is easier reach and use the menu functions. I prefer to mount it right next to my one rod holder so that the other side of my cockpit is completely free of obstacles.

It makes it much easier to swing your legs over on one side and get in and out of the kayak. This position is of course no good for paddlers, as it interferes with your stroke.

Lots of paddle kayaks have been made with available space in the cockpit between your legs. This is also a great spot as it won’t interfere with paddling but allows you easy access to play with the sounder functions.

To get power to the fish finder I use a small 12v 7-amp sealed battery, the type found on motorbikes or in mowers. They are also sold as flounder lights in boat shops and often come in convenient soft packs with a female cigarette lighter plug mounted on the outside for connection.

I then put a male plug on the sounder power cord and we are ready to plug in. With the included extension cord it can be charged in the car or placed on a standard car battery charger.

On most sounders the charge will last a couple of days of fishing. When it is used in the kayak I simply seal it up in a dry bag with the cord sticking out and place it in the hull of the kayak.

When it comes to running cables in and out of kayaks, I prefer to avoid drilling holes. Where possible, I file out notches in the inside of the outer ring of hatches. Use a round file to do it and then your cables can poke through the rim of a closed hatch.

It won’t work on some screw tops but if you can get away with it, later on the sounder can be removed from the kayak, the hatch changed and no evidence is left behind. Another way to do it is just drill a big enough hole, use a rubber grommet and some silicone to seal it.

For more info I have posted a video example of a sounder install on Youtube at www.youtube.com/watch?v=O8Y3pFg0Gu8.

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