Fishing blind: I hate it. There is a bit of mystery in the depths of lakes. The flat, wide expanse of water gives few clues as to what lies beneath or to where the trout might be, but a fish-finder helps.

Subtle changes on the lake bottom are often key to success in stillwater, yet such structure is often invisible from a pontoon boat or floattube. A long time ago I realized that a fish-finder isn’t just for boats, and that they greatly add to my ability to figure out lakes and make effective presentations to fish.

One thing that has always been problematic, however, is finding a fish-finder and mounting solution that works well on my preferred craft: a float tube or pontoon boat.

Sonar Solutions

Types of Solutions
There are three flavors of fish-finder devices that can be used on a float tube: a traditional wired fish-finder, which includes a display with cords that go to a transducer and a power source; the wireless fish-finders that run on batteries and connect to the transducer via a wireless signal such as Bluetooth, and finally, wireless transducers that use a phone or tablet as the display. An application provides the interface between phone or tablet and transducer.

I have tried all three of these types. All of these are viable solutions.

The first fish-finder I mounted to a float tube was an Eagle Cuda 168. It was a traditional, wired fish finder.  I wanted a fish-finder that would show depth, water temperature and fish at a minimum and still be somewhat compact as I sometimes hike into places to fish. I rigged a transducer mount using a bungee cord and a piece of PVC tubing about 18 inches long, bolting the display to an electronics junction box and stuffing the cords inside the box. I then attached the power leads to a 3AH 12 volt battery. This system worked well, once I was on the water. However, it was a bit unwieldy to set up, kind of sloppy, and was a pain to put away at the end of the trip. Though it was functional, it was just a little too much work to set up and take down. I used this system for a couple years, and then my friend Bob Andres showed me his Humminbird RF-15 Smartcast wireless fish-finder.

The wireless transducer for the RF-15 reminds me of a green rubber ducky from a distance. It’s designed to be cast, but for float-tube use, we simply tied it to a two-foot length of backing and attached it to our tubes. This system was really easy to use: Launch float tube, open float-tube pocket, toss rubber ducky in the water, push power button on display, done. It showed depth, temperature and bottom, but the detail was nothing like the Cuda. I resigned myself to being content with depth and temperature. Most of the time, that’s all you need. This system had another problem, though—one which was extremely frustrating and which Humminbird seemed unwilling to address. The transducers were built so you couldn’t change the battery when it died. You had to buy another transducer for $39 or so. The transducers could be hard to find. What’s more, when you opened a new transducer is was impossible to predict if it would work for one month or six months. If Humminbird would have made transducers that allowed battery changes, I’d probably still be using their unit. I have since found that it is possible to cut open the transducer, but minor electrical surgery and soldering is required to access and change the battery. I don’t have time for that.

The third type of fish-finder solution is those with a wireless transducer that uses your smartphone or tablet as a display. The only one of this type that I’ve used is the Deeper fish-finder. It is extremely compact in that all you have is your phone and a transducer. The transducer is a sphere about two and a half inches in diameter. It is designed to be cast, but I just tied it to my tube with a short piece of Dacron. The Deeper uses an application to serve as the interface between the Bluetooth transducer and your smartphone. Quality of the sonar picture is much better than I expected—better than the Humminbird mentioned above. It also shows temperature and has a variety of viewing modes. The only things I don’t like about the Deeper is I can’t use my phone and the sonar at the same time, and the battery life of the transducer is usually less than four hours the way I use it. The app uses phone battery up pretty fast as well. That said, the transducer is rechargeable, so a battery pack could be used to charge it relatively quickly.  Same with your smartphone.

In the end, while each provided something to the angler, all of these three solutions left something to be desired.

Full Circle
My last green rubber ducky (Humminbird RF-45 transducer) died last fall. I’ve given up on the Humminbird unit due to the transducer situation. Since my preference is to be able to keep my phone safe and available for use, I started looking for a wired fish-finder again. Much to my surprise and delight, I stumbled upon a website called I couldn’t believe what I saw—a professionally made, compact means of mounting wired fish-finders for float tubes and pontoon boats! I did some poking around on the site and found that they have portable fish-finder solutions for virtually any of the common fish-finder units on the market today (their sister site, has solutions for boats of all kinds, including inflatables).

sonarsolutions2.jpgI have the U2 Float Tube Fish Finder Mount. It includes a 2.9AH battery, the battery box, universal mounting base, mounting strap and the transducer mount. The strap holds everything in place on your pontoon or float tube. In fact, you can wear the strap around your waist or over your shoulder if you have to hike into a lake. The system is relatively compact, easy to set up, easy to re-charge and lets me use a wired fish-finder, which provides a better picture than any of the wireless fish-finders I’ve used. The transducer mount is especially ingenious. It allows for simple deployment of the transducer, and you can flip the transducer up out of the water and out of harm’s way when launching or beaching your craft.

I mounted a Lowrance Elite-4 CHIRP on my U2 mount. It’s is an extremely capable unit, providing not only depth and temperature but charting capability and DownScan imaging. The Elite-4 CHIRP has more capability than I need much of the time. The Elite-4x CHIRP, which lacks charting, or the Elite-3c would be less expensive alternatives.

If you’re serious about stillwater fly fishing, I encourage you to buy a fish-finder and a means to attach it to your craft. If you’re mounting to a float tube or pontoon boat, the mounts from Float Tube Fanatics are the best I’ve seen. Using their mounting system eliminates the guesswork of a do-it-yourself project. Get one, and don’t fish blind anymore!


George Krumm is a contributing editor for Fish Alaska magazine and can be reached at