Man Fishing in Kayak

Portable Fish Finders Are Convenient and Practical

Portable FishFinders Are Very Useful

Most fishermen agree that a portable fishfinder is a great tool for any serious angler and is a good addition to a fisherman’s tool kit. Outdoors magazines and websites alike show off the newest models for mounting on your bass boat or your Boston Whaler, but what if, like me, you travel a lot — for work, with family, and for fishing? What if your fishing adventures are not limited to a particular body of water or even a particular type of fishing?

If you’ve been considering buying a portable one for yourself, then read on for information about how they work and advice about how to pick the best one for your needs.

Types of Portable Fish Finders

Reputable companies that manufacture the traditional fixed fish finders for boat use — Garmin, Lowrance, Humminbird, etc. — also make portable finders. While there are many brands of portable units from which the interested fisherman can choose, there are also different features to consider. Each type has benefits in certain situations.

Portable Fish Finders consist of a fish finder unit with a three (3) to seven (7) inch screen, a plastic mounting bracket, a portable transducer, a small rechargeable 12 volt battery, and a carrying case to make all of the other parts easily portable. This variety of units is especially useful if you are transferring back and forth between small boats or kayaks. Many of them have a transducer that you can either float or hang over the side or transom of your boat.

Some are mounted to the gunwale with a clamp and arm that extends the transducer into the water. Another option is to temporarily mount the fish finder using a suction cup that attaches the transducer arm to the hull. A third option uses a float tube from which the transducer hangs into the water.

All of these options prevent you from having to drill through the hull in order to mount the unit to your boat. This feature also makes it easier for you to quickly transfer the device from one boat to another. Fish finders with this over-the-side type of transducer are particularly useful if you are fishing in an inflatable or fold-up kayak, which cannot support a hull mount.

The second type of portable finder is the Castable Unit, a newer variation. The castable unit syncs with the technology that most of us have everywhere we go these days — our smartphones. The castable fish finder has a small transducer that links with an app on your phone via WiFi or Bluetooth.

In order to use the app, you use a second rod to cast the floatable transducer into the water that you want to survey. By opening the app, you will be able to see the data collected by the transducer and transformed by the app’s software into easily interpreted images.

Castable devices are recommended for river fishermen and those fishing from piers or the shore. They have the advantage of having no wires, so they are not only easier to carry but easier to use in various bodies of water.

If you are looking for a more in-depth explanation of types of units, check out Fish Alaska’s article called “Sonar Solutions.

Nice Catch
Nice Catch

Portable Fish Finder Technology

Fish finders work using SONAR (Sound Navigation and Ranging), a method in which a transducer sends sound waves into the water. A transducer, also known as a hydrophone, is a device that converts a signal from one form of energy into another form. When the sound waves emitted by the transducer hit an object and reflect back to the receiver, the unit measures the time between the initial release and the return.

The unit’s software then calculates the depth and relative size of the object. The object may be a fish, structure, cover, or the bottom floor. Different models display this information differently, some as numbers and others as arches or pictures. If you are interested in a more in-depth explanation of how SONAR works, The National Ocean Service website offers both a detailed video and written explanation of the processes involved in SONAR.

Some portable finders use a more advanced form of sonar known as Compressed High-Intensity Radiated Pulse (CHIRP), which emits signals at multiple frequencies, thus increasing the likelihood that it will detect more objects since different objects reflect sound at different frequencies. The more complex the technology, however, the greater the price tends to be.

Important Features To Consider

In addition to the basic SONAR and/or CHIRP technology which runs a portable fish finder, there are other “tech” issues that you need to consider as you determine which type of finder is right for you.

Screen Size and Display

Portable units tend to have smaller screens than mounted units, which makes sense since that screen makes the unit heavy and you have to carry it with you. Typical portable units will have three (3) to five (5) inch screens.

The resolution of your unit is measured in horizontal and vertical pixels. The more pixels that you have on your screen, the more detailed your picture. Since detail is important when you are trying to distinguish a fish from a plant or floating debris from a school of fish, I recommend that you go with the fish finder with the highest pixel ratio that you can afford.

For castable units your screen is your smartphone, so the screen size and pixel resolution will depend on your phone.


The software in your fishfinder will determine how the data it gathers is displayed. There are several different ways that the software can show information. Some units have software that presents the SONAR or CHIRP data as icons so that you can distinguish between the cover and the fish.

Fish ID technology analyzes the data and uses icons to show plants, rocks, and schools of fish. While this technology is not always accurate, it does help because it gives you information that you can’t get in any other way. This level of technology also helps you to see objects separately and more clearly.

Other instruments display the scanning data they receive as arches. The way that these show the information gleaned by the transducer is that objects that are not moving show up on the display as a straight line, while moving objects, like fish, show up on the screen as arches. The size of the lines and the arches indicate the size of the objects that they are representing. In other words, bigger fish make bigger arches on these displays.

Whatever display you prefer, it will probably take some practice to learn to read it accurately. Being able to tell the difference between fish, cover, and noise takes experience, time, and repetition. Wikipedia – a great first source for basic information – has an article about the Deeper Fishfinder, which explains some rudimentary information and will give you a good sense of how one of these units works.

WiFi / Bluetooth Connectivity

With WIFI enabled Finders you don’t need to worry about wires. Units that connect via WiFi give you access to high-speed internet at the same time. Devices that use Bluetooth connect to units that are within close proximity to them. The site Techopedia gives a clear explanation of the differences, but essentially the main difference between WiFi and Bluetooth is that WiFi enables the unit to connect you to the internet.

Portable Fishfinder
Portable Fishfinder

Enhanced Technology Features for Portable units:

There are a number of fancier features that you may want to have on your portable unit in order to enhance your experience.

  • Some units come GPS enabled. The GPS feature allows you to create real-time maps and to auto-chart your routes. This is handy if you are planning to temporarily mount your fish finder on a kayak or if you are planning to travel somewhere that you haven’t been before in order to fish.
  • A dual-frequency transducer is better because it sends out more signals at different frequencies, increasing your chances of getting accurate information.
  • Some portable units use down scan technology while others use side scan. Side imaging technology gives you a more accurate picture of what is under shallow waters because it covers more area than down imaging does. Down imaging gives you a better picture in deeper waters. Down imaging gives you a view of what you would see if you were the fish and were looking at the scene under your boat from the fish’s vantage point. Side-scan technology is good in shallower water. It gives you a view that is more like what you would see if you were flying over the area in an airplane and could see down into the water.
  • Power usage is another important technological feature to consider. While some portable units can be run using AAA batteries, others require a 12 volt. Some units have a much longer battery life, and the battery life for a portable unit is important. Ideally, you want something that will last on a day-long portage trip without you having to lug along a battery charger.

Price for Portable FishFinders

Price is always a consideration when buying new fishing gear, particularly high-tech gear like a fish finder. Portable units are cheaper, on average, than fixed or permanently mounted funits. Their smaller size leads to a lower price. These portable devices tend to cost between $100 and $300, which is a good deal in my estimation. After all, the information that a portable device can provide you is invaluable.

Pros and Cons of Portable Fish Finders

Like any fishing tools, there are good and bad aspects of portable units. Consider what type of fishing you do most often as you consider the positive and negative aspects of these devices.


  • You can fish without buying an expensive boat and still have all of the advantages that fishermen with fixed fish finders enjoy such as knowledge of depth, temperature, and fish location. For an example of how this can help improve your fishing success, check out this video from 1Rod1ReelFishing. With a portable unit, you can rent a boat or you can even fish in places where a larger boat is impossible to transport.
  • Portable finders tend to be more cost-effective than fixed ones.
  • Portable units don’t require you to drill through the hull of your boat in order to permanently mount the transducer; therefore, they tend to be easier to use right out of the package.
  • The portable ones offer more flexibility for the angler, allowing you to fish in diverse locations with the same unit. Portable ones are even good for ice fishing. Most portable units have batteries that hold their charge for eight (8) to twelve (12) hours. With the longer battery life, not having to carry a battery pack with you can make your experience easier and more enjoyable.
  • Many portable devices have depth ranges up to 300 feet, making them comparable to fixed mount finders when you are fishing the shallower lakes and rivers.


  • Portable finders are not cheap.
  • If you are using a castable finder, it is possible that you may lose it. Think of it as a really expensive lure. What happens when, like a lure, you get your fish finder snagged on a shoal or in a tree. It is possible that you will lose it, and that would be an extremely expensive lure to lose.
  • Castable ones can lose connectivity during the cast. The motion and jarring nature of casting and splashing into the water sometimes causes the smartphone app and the castable transducer to disconnect from one another. The only solution is to reboot the smartphone app so that it can reestablish a connection with the transducer’s signal. While this is not a horrible problem, it can get annoying if it happens multiple times.

Recommended Accessories

Depending on which type and model of portable fish finder you choose to buy, you will want to invest in certain accessories to make the most of your experience.

  • If you are pairing your castable unit with your smartphone, you should definitely invest in a waterproof case for your phone. The chances that you are going to get wet when you are fishing are pretty good. You are after all usually surrounded by water. A waterproof case will help to protect your phone from splashing or accidental submerging.
  • As anyone who has ever fished from a boat, a pier, or a bank knows, it only takes one slip or one quick motion for a pair of sunglasses or a phone to slip out of your pocket and into the water. Nothing is worse than the feeling of watching an expensive piece of equipment sink out of sight. Also, it isn’t helpful to have a waterproof case if your phone is MIA at the bottom of the lake or is 200 meters downstream in the rapids. Therefore, your waterproof case should also float, so that when you drop it, you can quickly retrieve it.
  • If you are buying a castable unit, you will need an extra rod to use to cast out the finder. You will want a stiff rod and ten to twenty-pound test line depending on the weight of the castable finder.
  • If your portable finder is not a castable model but instead is the more traditional type, then you should make sure that you have a bag so you can transport your unit easily. Make sure that your bag allows you to carry not only the display itself but also the transducer, battery, and any wires that you might need.


This summer I was able to fish in a variety of places. We went on a family trip to Beaver Island in Michigan, which provided me with a one day fly fishing excursion to the archipelago flats for carp. Another trip out west gave me a week in Montana and Idaho, camping and fly fishing in the St. Joe River for trout.

Each year, I get the opportunity to fish in rivers and lakes, both big and small, and every couple of years, I spend time deep sea fishing in Florida. Sometimes, I’m lucky enough to go fishing with friends whose boats are equipped with the newest and greatest fish finders. However, when I’m river or kayak fishing, or even when I’m shore or pier fishing I realize how important having one of these units really is.

This past Christmas, my brother gave me a portable fish finder, which I was able to use in the spring and summer, and I can tell you that the portable fish finder is worth the money. It is not a perfect tool by any means, but when I travel or when I fish rivers or the shore, I have found it to be a highly useful device.

If you are a fisherman who travels or one who likes to fish in different types of water and from different types of boats, a portable device – either the standard or the castable variety – might be a good investment for you. The best fishfinder for you will depend on where your fish and what you want to catch. Do some research and find the unit that best fits your needs.

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