Three parts to get right: the display (on a track, in your sightline), the transducer (under the hull or in a scupper, always in contact with water), and the battery (small 12V lithium in a sealed box). Track-mounted battery boxes with a built-in transducer arm make it drill-free.
Mounting the display
Put the screen where you can glance at it without turning your head from the water — usually on an accessory track just ahead of the seat. Keep it low enough that it doesn’t catch your line or block casting. A track mount lets you angle it against glare and remove it between trips. Choose a screen size that suits your deck — 4–5" is the kayak sweet spot.
Placing the transducer
The transducer must stay in contact with water to read. Two common approaches: mount it under the hull on an arm, or shoot through a scupper hole with a scupper mount. Through-hull (glued inside) works on solid hulls but you lose some detail. Keep the transducer clear of your paddle stroke and any turbulence. This is where a track-mounted transducer arm earns its keep.
Powering it cleanly
A small 12V lithium battery (7–10Ah) runs a 4–5" unit all day and weighs a fraction of sealed lead-acid. House it in a waterproof box — track-mounted battery boxes that integrate the transducer arm and a finder platform are the tidiest, no-drill solution. Route and secure all wiring along the gunwale so nothing snags.
Castable: the no-mount alternative
If you’d rather not mount anything, a castable sonar pairs with your phone and needs no battery box or transducer install — ideal for minimalist or multi-boat anglers.
Frequently asked questions
Either under the hull on a transducer arm, or shooting through a scupper hole with a scupper mount. It must stay in contact with water and be kept clear of your paddle stroke and hull turbulence for a clean reading.
A small 12V lithium (LiFePO4) battery of about 7–10Ah runs most 4–5 inch units all day and saves significant weight over lead-acid. Keep it in a sealed, waterproof box — ideally a track-mounted battery box that also holds the transducer arm.
Yes. Track-mounted battery boxes with an integrated transducer arm and screen platform let you install a complete fish-finder system without drilling into the hull, and you can remove it between trips.