Boat-specific setup

Fish Finder on an Inflatable Boat: Mounting Without Drilling

Know which kind of inflatable you have

"Inflatable" covers very different boats, and the right transducer mount depends almost entirely on the hull type.

Transducer mounting options that work

Transom board mount

If the boat has a solid transom board, a standard transom-mount transducer bracket can be screwed into it, the same way you would on a small aluminum boat. Many owners prefer to screw a small sacrificial mounting plate (starboard-type polymer or sealed hardwood) to the transom first, then mount the transducer bracket to the plate. That keeps the screw holes in the replaceable plate and lets you fine-tune height.

The key detail on an inflatable is height. The transducer face needs to sit slightly below the lowest part of the hull at the transom so it stays in solid water. On boats where the floor or keel sits lower than the transom board, you may need a bracket or plate that drops the transducer further than you would expect.

Clamp-on and motor-bracket mounts

Clamp-style transducer mounts grip the transom board like a small outboard does. They are popular because nothing is drilled at all and the transducer comes off in seconds for trailering, deflating or storage. Some clamp onto the outboard or electric motor's mounting bracket instead. The tradeoff is rigidity: a loosely clamped mount can rattle or kick up, so check it after the first run.

Transducer arms

Arm mounts (the kind sold for kayaks and canoes) attach to a rail, a frame or the transom board and hold the transducer down in the water beside the boat. They suit inflatables with rowing frames or no usable transom, and they can be lifted out of the water when beaching.

In-hull on a RIB

On a RIB with a solid fiberglass hull, bonding a transducer inside the hull (or using a liquid-filled in-hull tank) lets the sonar shoot through the fiberglass with no holes at all. This only works where the laminate is solid; cored sections or aluminum hulls block or badly weaken the signal. Expect a little less sensitivity and no water temperature reading.

Mounting the display

Inflatables rarely have a console, so think about where your eyes and hands will be. On a tiller-steered inflatable that usually means close to the stern, within reach while you steer.

• Transom board: a small base or ball mount screwed to the board, often on the opposite side from the motor.
• Seat or bench: a ball-and-arm mount on a rigid seat lets you swing the screen toward you.
• Rowing frame or rail: clamp-on rail mounts avoid any drilling.
• Glue-on fabric mounts: accessory pads and D-ring style bases are made for PVC and for Hypalon/CSM fabric. The two materials need different adhesives, so check what your boat is made of and use the matching kit.

A ball-and-socket arm is especially useful on an inflatable because the boat flexes and your seating position changes. Being able to tilt the screen away from glare and toward wherever you are sitting matters more here than on a boat with a fixed helm.

Power without a big battery bank

Most inflatable anglers run either a small outboard (often with no charging output) or an electric motor powered by a single battery. That shapes your electronics choice.

• Separate small battery: a compact sealed lead-acid or lithium battery dedicated to the fish finder keeps sonar clean and avoids motor noise. It is also easy to carry.
• Shared motor battery: workable, but electric motors can add electrical noise to the sonar screen, and a fish finder will keep draining a battery the motor also needs to get you home.
• Runtime: look up the unit's rated current draw, multiply by your hours on the water, and add a healthy margin. Imaging modes and a bright backlight draw more.

Keep the battery in a box or bag so terminals cannot touch the floor or the fabric, and fuse the power lead close to the battery with the fuse size the fish finder maker specifies.

Which sonar type suits an inflatable?

For most people a compact unit with 2D CHIRP, down imaging and GPS is the right fit. GPS lets you mark the spots you find, which matters when you launch from different beaches and want to return to the same rock pile or drop-off. Screen size of 4 to 7 inches is typical; larger screens are harder to mount securely and draw more power.

Settings that help on a light hull

1. Start on automatic sensitivity, then lower it slightly if surface clutter from chop fills the top of the screen.
2. Turn on or raise surface clutter filtering if bubbles from the hull and waves create noise near the surface.
3. Use a wider-beam frequency when the boat rocks; a narrow beam can lose the bottom when the hull rolls.
4. Keep speed steady when using down or side imaging. Light boats speed up and slow down with every wave, and imaging is sensitive to that.
5. Set a depth offset if your transducer sits well below the waterline, so displayed depths match the chart.

Trailering, deflating and storage

The big advantage of an inflatable is that it packs away. Build your electronics to match: quick-release display mounts, a transducer that comes off its bracket, and a cable you can coil without kinking. Avoid leaving the transducer clamped on while you drag the boat up a beach, since the face and bracket are the first things to hit sand and rocks. Rinse the transducer and connectors with fresh water after saltwater trips and let them dry before packing.

The verdict