Portable and Castable Fish Finders

Electronics for small boats and for all anglers looking to prospect new locations
Portable and Castable Fish Finders
Because of the app interface, castable products can offer all kinds of functions in addition to sonar, such as fishing-log pages. Courtesy Manufacturers

Combine a small-boat market now flooded by tiny skiffs, kayaks, and paddleboards with the wildly dynamic field of smartphone- and tablet-app development, and you get some pretty amazing portable marine electronics. In fact, during the past 18 months, I’ve seen a proliferation of castable sonar products that transmit key data to devices such as iPhones and Androids.

Before that time, Humminbird made the best-known castable unit on the market — the SmartCast, which paired with a wrist-/rod-mount display. Now anglers can choose from products like Deeper, FishHunter, iBobber and SonarPhone’s T-Pod, which range in price from $100 to $230.

Because of the app interface, castable products can offer all kinds of functions in addition to sonar, such as fishing-log pages, fish databases, solunar information and weather reports. They also offer social-sharing and location-saving capabilities.


But because of their size, castables also come with limitations, particularly for saltwater use. Anglers who want greater signal strength, more functions, and improved rough-water capability can step up to slightly larger portable sounders and sounder/GPS combos. Here’s a quick look at some of the current products.

Castable Fish-Finder Units

These units function just as they sound: You tie them to the end of a fishing line, and then cast or toss them to your chosen location. You can also tow one slowly behind a vessel. They’re waterproof, they float, and they activate as soon as they touch a liquid surface.

Deeper Smart Fishfinder

Deeper Smart Fishfinder
The 2.6-inch diameter Deeper Smart Fishfinder sphere can be cast or pulled slowly behind a vessel. It reads depths to 130 feet and uses a Bluetooth connection. Courtesy Manufacturer

This round, bobber-shaped sonar unit measures 2.6 inches in diameter and weighs 3.5 ounces. It features several different attachment points, so you can cast it from varying heights.


The unit incorporates a dual-frequency transducer (90/290 kHz). It reads depths to 130 feet and operates within 160 feet of its paired device. Deeper uses a Bluetooth connection, and is compatible with a wide variety of iPhones and iPads, as well as smartphones and tablets running Android 2.3 and above.

Deeper holds a 3.7-volt rechargeable battery that provides up to six hours of running time. Its free app comes with a fishing log, weather reports, water-temperature readout, fish icons, fishing activity calendar, and a base map (not a marine chart) with satellite overlay, which can be used to save hot spots. The hardware costs $229.99.


Appetite Lab describes its FishHunter sonar as baseball size; it weighs 4 ounces and features one attachment point.


The FishHunter’s 381 kHz transducer can read depths to 120 feet. The unit also provides user-adjustable depth ranges (for 10, 20 and 30 meters) that automatically change the sonar pulse length for optimal presentation. The transducer-beam angle widens from 16 degrees at 3 decibels to 22 degrees at 6 decibels.

FishHunter uses Bluetooth to pair with iOS and Android devices; its stated casting distance is 80 feet. The unit lasts six to nine hours on a charge from its 3.6-volt internal battery. The free app offers a fish database, water temp, log book, moon forecasting, mapping (though not with marine charts), and a raw-data view that displays like a traditional sounder rather than showing just fish icons. The hardware costs $229.


iBobber Bluetooth Smart Castable Fishfinder
iBobber’s Bluetooth Smart pairing draws less power than traditional Bluetooth and Wi-Fi do. Courtesy Manufacturer

At press time, iBobber was available only for Apple phones and tablets using Bluetooth Smart (Bluetooth low energy), but the company expected it to pair with Android 4.3 by now. Bluetooth Smart allows for more continuous connectivity, iBobber says, and it draws less power from your device’s battery than traditional Bluetooth and Wi-Fi do.


The iBobber measures 2.3 inches in diameter, weighs 1.7 ounces and, not surprisingly, looks like an oversize freshwater bobber. It uses a 118 kHz transducer. The company says it measures depths to 135 feet and operates 100 feet away from its paired mobile device.

The iBobber marks fish based on their size — whether under 15 inches or longer than 15 inches — the company says. Its free app comes with loads of functions. The hardware costs $99.99.

SonarPhone T-Pod

The 4-ounce T-Pod is the castable unit within Vexilar’s SonarPhone line. It uses a 125 kHz transducer with a 30-degree cone. The 3.7-volt rechargeable battery lasts four hours on a charge.

SonarPhones employ Wi-Fi rather than Bluetooth to establish a connection with your iOS or Android device. As a result, the T-Pod has a transmit range of up to 100 yards, and it can pair with multiple devices at the same time. The 400-watt T-Pod transmits data at 100 mbps.

The free app displays a traditional sonar view, and can show a zoomed-in range as well as other conventional sounder features. It reads depths to 120 feet. T-Pod costs $129.95.

Portable Units

Garmin, Humminbird, and Lowrance all build portable kits that work with a variety of their smaller sounders and sounder/GPS combos. Most include a sealed lead battery and a suction-cup transducer. Vexilar makes a portable SonarPhone T-Box unit that pairs with an iOS or Android device (as the castable units do), and works with Navionics’ new Boating app to provide chart plotting in a split-screen view with sonar readings.


Garmin Portable Fish Finder Kit
Garmin sells a portable kit that includes a carrying bag, dual-beam suction-cup transducer, rechargeable battery and charger. With the kit, any echo unit can be made mobile. Courtesy Manufacturer

Garmin offers three solutions for portable fish finders. The echo 151 ($179.99) and echo 301c ($299.99, color) portable bundles include a carrying bag, dual-beam suction-cup transducer, rechargeable battery and charger. A portable kit ($129.99) is also sold separately, so anglers can make any echo unit mobile.


Humminbird Helix and Portable Conversion Kit
Humminbird’s Helix and its PiranhaMax (not pictured) sonar units are compatible with the company’s portable conversion kit, which includes a suction-cup transducer. Courtesy Manufacturer

The PiranhaMax and brand-new, small-format widescreen Helix units easily fit the company’s portable conversion kit in a price range from about $170 to $400. Both series are available as sonar only or sonar/GPS combos.

Humminbird Fishin' Buddy
Humminbird’s Fishin’ Buddy is an all-in-one-device that clamps onto a vessel. Its top is a sonar head unit mounted to a tube. At the bottom of the tube lies the transducer. Courtesy Manufacturer

The company’s Fishin’ Buddy is an all-in-one device that clamps onto a vessel. It features a sonar head unit atop a 24-inch tube, capped by a transducer. It costs $129 to $270.


Lowrance All-Season Portable Pack
Lowrance’s portable pack accommodates Elite fish-finder units and even includes tackle boxes. Courtesy Manufacturer

Lowrance’s Elite 3-, 4-, and 5-inch units (including the new 3x) can be sold with an all-season portable pack that includes a transducer, bag, battery, charger, and tackle holders. The Elite-3x All Season costs $249.

SonarPhone T-Box

SonarPhone T-Box
The SP300 T-Box portable system pairs with a mobile device to display sonar readings. With a Navionics app, it can also show marine chart. Courtesy Manufacturer

Vexilar’s SP300 T-Box portable system costs $199.95, and pairs with a mobile device to display sonar readings. Install a Navionics Boating app ($10 to $50), and your phone or tablet provides both a marine chart and a sounder (with the new SonarCharts Live) in a split-screen view. The unit comes with a dual-beam 83/200 kHz transducer and reads depths to 240 feet. Curious? Watch video of Navionics SonarCharts Live on SonarPhone.