Float Tube Fish Finder

I first added sonar to my float tube in the mid ‘80’s. My first unit was an old Humminbird flasher. I powered it by wiring two 6-volt lantern batteries in series. I set up the display by just balancing it on the front of my tube…hoping it did not topple into the water. The transducer was bolted to a piece of wood that I hung over the side. It was rude, crude, bulky and heavy. But, it worked and it whetted my appetite for something better. It wasn’t long before I retired the flasher and bought a low end LCD unit. Eagle was just getting into the market with basic units for a reasonable price. They were ideal for tubing because I didn’t need all the foo-foo stuff anyway.

I quickly learned to rely on sonar to determine water depth and to find fish. It didn’t take long to convince me that fishing without it was fishing blind. My earliest models provided only the most basic readings…depth, bottom contours, fish blips, etc. I did not own a unit with temperature readings for several years. But, by combining my newfound underwater vision with the basic knowledge and skills I had already developed, I greatly improved my catch rate and my personal enjoyment of floatation fishing. As with most electronics sonar technology has changed and improved over the past few years. We can get more for less today. And even “low end” are often better than some of the higher priced stuff that was available only a few years ago. There are also several excellent float tube fish finder mounts available on the market.

Installation of your sonar system will ultimately depend upon the type of unit you buy, the size and shape of your craft, where you want to locate the display, what kind of transducer you get and where and how you want to mount it. Sonar displays can be simply stuffed in a pocket, with the screen visible to the angler. Or, they can be securely mounted somewhere on your tube or toon. Many floatation fishermen like a quick-connect “ram mount” that is permanently connected to their craft. You attach the display when you are ready to fish and it swivels easily to face any direction. The standard mounting brackets on most sonar systems can be lashed onto a tube or toon
with one inch nylon strapping. These brackets can also be bolted directly to a pontoon frame or to a PVC framework secured on a float tube. Mounting brackets are usually designed so that the display part of the system can be disconnected and removed for transport and security.

Some U-boat and V-boat designs include ample pockets that allow you to make wood base mounts inside the pockets for your displays. You can also make mounts that fit down inside the drink compartments at the fronts of those pockets. Whatever method you use for setting up the location of your display, be sure to consider visibility, safety and quick setup and takedown.


Sonar units we buy for tubing and tooning are made for boats. They usually include a long length of cable between the display screen and the transducer to allow wiring on a boat. When setting up one of these systems on a tube you don’t need all that cable. It gets in the way so you have to roll it up and secure it with tape or a zip tie or it will overtake your whole craft and leave you hogtied in the coils. Once you have the excess cable under control stow it out of the way. Unless you have to repair a split transducer cable, do not try cutting and splicing it. There are several individual wires running through the black plastic outer covering. They are color coded, and you can successfully splice each one separately, but it is tedious and subject to causing malfunctions on your sensitive electronics. Not a good way to shorten the extra cable.

float tube fish finder

Fish Finder Features To Consider

Adding electronic “eyes” to a tube or toon can be intimidating to a first time sonar buyer. There is a bewildering and confusing choice of makes, models and features. These can be intimidating even to more seasoned sonar users. So, how do you decide what to buy, how much to spend and whether it is the right unit for your pride and joy? The good news is that floatation fishing does not place the same high demands on a sonar system that serious boat fishing does. So, we don’t need the high wattage and all the bells and whistles that an ocean-going yacht would find necessary for their system. The following terms are the most important to consider when shopping for sonar…for tubing and tooning.

PRICE: Unless you have more money than good sense there is no good reason to invest more than $100 to $200 to provide underwater vision for your inflated fishing platform. Cost is usually a reflection of high wattage, deeper signal penetration, speedometer, color or whatever…mostly unnecessary for fishing shallow waters in a slow craft. This is a simple “ram mount”, which allows for quick installation and takedown…and easy
adjustment of viewing angle. It begins by using long screws to secure a 2”X2” piece of wood inside the front of the pockets…running the screws in through the cover from the outside. Then you cut through a
½” PVC cross to provide two pieces like the one in the picture. Use one on the sonar display mount and one on the wood. The riser is a 4” piece of unglued PVC to allow free movement. It can be any length.

POWER: The power of the sonar signal and output is expressed in watts. The higher the wattage the more power it drains from the small batteries used on tubes and toons and the shorter the amount of time before they run out of juice. The single advantage of having a high wattage sonar system is the potential for seeing your lure below you, on the screen, in “real time”…and reel time. This can be helpful when you are vertical jigging. You can see the fish coming through, and your jig too, so you know whether to raise or lower it to put it in front of the fishies.

CONE: The cone is the area in which the signal from the transducer is sent toward the bottom. It widens as it goes downward…in a cone shape. Transducers come in several cone angle options…from 9 degrees to 60 degrees. The narrower the cone angle the smaller the area it will display. Narrow cone angles are better for deep water and wider cone angles are better for the shallower water typically fished most often by tubers and tooners. A good all around cone angle is 20 degrees. That is also most common on “standard” sonar setups. Some units offer variable cone angles which you can choose from a menu.

SIDE SCANNING: Some sonar systems allow optional or full time side scanning…being
able to see horizontally as well as straight down. This can be a great tool when targeting species
that often suspend or cruise at depths well above the bottom…like crappies, trout, etc.

DISPLAY: The display screen is your window to the underwater world beneath you. It is good to have as much information as possible and even better to know how to read the display and to translate it into more effective fishing tactics. Here are some terms and their importance: Pixels: Your screen displays the information using small dots…or pixels…in varying shades of grey…or color. The bigger the screen and the higher the pixel count the more resolution you will have in the display output…the better the detail. Small screen displays will work but larger ones are easier to read and interpret. Color is pretty but provides no real advantages.

Gray line: This is a feature that helps define the bottom composition…whether the bottom is hard or soft. Good information for targeting some species.

Alarms: Some units have optional alarms you can select from the menu. These include fish alarms…for when fish pass through the cone. They may also provide a signal for shallow water. Obviously, this is not nearly as critical to tubers and tooners as to boaters.

Fish signals: Most sonar systems have variable methods for displaying fish signals. Some show fish as “inverted V shapes”…like little boomerangs…when you go over them with any speed. But, when fishing from a tube or toon, and moving slowly or not at all, the fish show as flat lines. Another option is “Fish ID”. This displays fish as little fishy icons…of varying sizes. This option is quick and easy to read but is also less accurate and more subject to false readings.

Digital Depth Readings: It is often critical to know the exact depth at which you are fishing. A large display of that number helps you keep track of the changing depths so that you can keep your craft in the right “zone” once you determine where the best fishing is. Some sonar units even display the depth of each fish target registered on the screen. That can be helpful too, especially if your system does not have “real time” display for showing your lures.

Temperature Readings: Very important to know water temperatures, especially during times of transition when a few degrees difference in temperature can make a lot of difference in fish activity or location. A “must have” feature for most tubers and tooners.

Speedometer: Not necessary for tubing and most tooning but vital to anglers who carefully monitor trolling speeds on their boats or toons. GPS speed readings are generally more accurate.

GPS: As previously mentioned, having a global positioning system can help both with safety and with fish locating. But, to include it as part of the sonar system for your tube or toon adds to the power drain on your small battery. Better to have a handheld or separate system.

Be sure to go to the website for the manufacturer of any sonar system you are considering. Look for tutorials or online video demos. This will give you a better feel for what the unit will do and not do…and if it will work for your style of fishing. Or, if you are shopping at a well-appointed fishing store visit the sonar section and ask to see the demo mode for the units they have on display.

This topic could have been included under the heading of Shopping. But, there are variations in transducers and they are important enough to be given separate treatment. The transducer, on a sonar system, is the electronic component that transmits signals down and out into the water and then collects echoes that bounce back off the bottom or other objectswithin the cone. It relays the returned signals back to the “brains”…the display box…and these impulses are translated into readings on the screen.

As mentioned, there are different cone angles available for transducers. There are also varying options as to the type of transducer shapes and mounting hardware. Some are designed to “shoot” through the hull of a boat. Not applicable for tubing or tooning. Others are shaped like hockey pucks and attach to a flat surface under the water. Again, not the best choice for floatation fishing, although they can be made to work.

Arguably the best transducer design is the “skimmer” type. These are shaped like a foot and are usually mounted on the transom of a boat so that they ride pointing “toes outward” and shooting their signals downward. Skimmer ‘ducers typically come with brackets that are easy to mount on PVC, wood or other materials. Ideally, you want a light and compact transducer mount rod that can be easily moved up or down when launching or beaching your craft.

When you mount a transducer on a tube or toon you should use a flexible connection. In other words, the mount should be easy to raise and lower. This reduces the potential for damage to the sensitive transducer when you launch or beach from hard ramps or over rocks. Also, you do not need to mount the transducer so that it rides deep in the water. As long as it remains below the surface of the water when in use it will function okay. The deeper it rides the greater the potential for tangling…in line, weeds, nets, etc…. and for getting damaged by contact with hard objects.

fish finder for float tube


Virtually all sonar systems compatible with tubes and toons are built to operate on 12 volt DC batteries. The good news is that you don’t have to try to figure out how to carry a heavy deep cycle marine battery on your poor little float tube. Any 12 volt battery will run your sonar…but for how long? There are a lot of variables in the wattage of sonar systems and the amp/hour ratings of batteries. The higher the power of your sonar unit the more juice it will drain from your battery. The higher the amp/hour rating of your battery the longer it will supply power to your sonar. The most popular sonar setups for tubing and tooning average from 500 to 1000 watts
output. Some good ones are 1500 watts or higher. Again, the higher the wattage the shorter the time you can run your sonar on any given battery.

The battery most often purchased for use with portable sonar systems is rated at 7 amp/hours. That means it will put out 7 amps for one hour, 1 amp for 7 hours, or any other mathematical equivalent. An average tuber’s sonar sucks about a half amp per hour. Theoretically you can run it continuously for 14 hours. Output is affected by heat and cold…and other factors. In the “olden days” my sonar batteries were acid filled motorcycle batteries. They were potentially dangerous…acid spills, fumes, etc. And, they did not last for more than a year of use on my float tubes. Today most tubers and tooners use SLA (sealed lead acid) batteries for running sonar on their craft. These are completely encased in hard plastic and there is no danger of spilling acid on you or your gear. You can tuck them anywhere you have a suitable spot for them. SLA batteries last for years if you treat them right. They are not “deep cycle” batteries. You should not drain them until they fail and they should be kept at a high charge level even when not in use. Top them off before a trip and recharge them as soon as you get home.
Because SLA batteries are widely used as backup power sources, for a variety of applications, they are available in many sizes, shapes and amp ratings. While the 7 amp size is the most common for portable sonar uses you can get by very nicely with smaller batteries…especially if you have a lower wattage sonar system.

The sonar I use is rated at 800 watts and I can fish a full day without draining my 4 amp battery. I charge it up to over 13 volts output before a trip and when I check it on the volt meter after returning it is usually still over 12.5 volts. You should never run the battery much below 12 volts and some sonar systems will shut down when power drops to 10 or 11 volts.

float tube battery mount