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Fish Finder For Kayak: How to Choose ? – Complete Guide

Fishing is fun and interesting…but only if you actually catch some fish at the end of the day. This makes a fish finder an important device that should always be among your fishing gear.

A fish finder points out the best spots for fishing and massively improves your chances of going home with a haul. And it’s easy to use a fish finder as all you have to do is mount it on your yak and you are good to go. Fish finders also have other features like GPS allowing the device to serve as a navigational tool helping you stay on course and monitoring speed.

There are fish finders with basic features while others have more advanced functions. Below, you’ll find a buying guide to help you choose the best fish finder for your kayak. You’ll learn how a fish finder works, how to mount one, and the factors to put into consideration when shopping for a fish finder. Here we go.

How Does a Fish Finder Work?

For one who doesn’t know what a fish finder is or what it actually does, you probably want to know what it is, likewise, what it does before deciding whether you need one, or going to buy one. A fish finder, just as it sounds, is equipment capable of discovering the location of fish(es) in water. It uses what is known today as sonar tech.

The device can detect reflected pulses in the form of sound which is a result of the movement of fish(es) from underwater. A typical fish finder shows its readings on a screen which the user would then interpret. These readings, if properly interpreted, would enable the user to locate shoals of fish(es). Some would even enable you to see very deep into the water, you’d be able to differentiate the fish(es) from normal underwater debris.

The fish finder gives you an edge, as the knowledge of the location of where you can find shoals of fish(es), prevents you from just casting your fishing nets into locations where there are little or no fish(es). Fishing is more fun and less stressful with the fish finder.

How To Mount a Kayak Fish Finder?

When trying to install your fish finder, your kayak design goes a long way in how you’d have to fit the fish finder to your kayak. Some kayaks come with a spot ready-made for you to mount the fish finder. With this type of kayak, you’d have little or no problem installing the head unit, power source, and the transducer of your fish finder.

In cases where your kayak doesn’t have a mount for fish finders, the display unit can be mounted to your gear tracks or you use your discretion to mount the fish finder anywhere you deem suitable. This should be where you’ll be able to comfortably see the screen. In your connection to the power source, you most definitely want to keep the battery away from where it can get in contact with water to ensure it’s safe and dry at all times.

Also, you probably don’t want the wires out of your way. The hull is a good place to put the battery. Also, the wires can be run through the hull although you may have to drill a hole in your kayak.

How To Power Your Fish Finder?

You need a power source to operate your fish finder and this means you need to bring a battery along on the fishing trips. The most economical type of battery to be used for your kayak finder would be the Sealed Lead Acid Type(SLA). This is similar to a typical car battery, with both working on the exact same principle.

As the name indicates, the acid is sealed into a case made of plastic and this helps to avoid any risk of spillage when kayaking or fishing as the case may be. Another battery type suitable for your fish finder is Lithium batteries. These batteries, unlike the SLAs, appear to be lightweight and portable.

In fact, the lithium battery of similar capacity to the SLA would offer you more time of use because, in the SLAs, the battery capacity shouldn’t be used below the 50% mark to ensure its durability. Portable fish finders use AAA batteries or lithium batteries.

Side Image vs. Down Image

The direction in which a particular fish finder’s transducer emits its sonar waves determines the kind of image it produces on the screen. Some direct their sonar waves downwards, beneath your boat and such transducers are said to produce down imaging.

There are those that direct their waves towards the side of the boat and are said to produce side imaging. Both types are very effective and can help you find fish. They both have advantages over the other. Your choice of selection should depend mostly on where you do your fishing.

When fishing in shallow water (or when you intend to scan for shallow diving fish) the more useful imaging system is the side image. As opposed to this, when fishing in deep water, the down image would come in handy, since the sonar waves are sent downwards.

Side Imaging


  • Side imaging enables quick scanning of more water since it can view two directions at the same time.
  • With the side imaging, you have a better picture of your environment, since they offer you a larger perimeter than the down image finders.
  • They are better at finding fish below small inlets and bays. Their orientation provides you with a better view than the down imaging system.
  • They offer more clarity, providing you with a more distinct image compared to your down image finder.


  • They are more expensive than the down image finders
  • They do not give a clear view of what is below your kayak
  • Must be operated with your kayak moving at low speed, although the larger perimeter they cover subsidies for this.

Down Imaging


  • Very efficient when fishing in deep waters
  • They also offer clarity when used at high speed, making you able to quickly race across the lake when finding another potential fishing position


  • They provide you with much less information about your environment, especially when you compare them with the side imaging finders.

Fishing Kayak fish finder guide

How to Choose Your Kayak Fish Finder?


One important thing to note when choosing accessories and gears for your kayak should be their durability, even when exposed to unfavorable weather conditions. Water resistance should be the most paramount since your kayak and its accessories would be used on water and there is a high tendency for your accessories to come in contact with water.

The best fish finders are those made to survive constant exposure to water and sunlight. Before deciding your choice of fish finder to purchase, ensure it has a high IP rating. The IP means “ingress protection”. Fish finders with high IP ratings are water and dust-resistant.

Ensure that the fish finder you go for has an IP rating not less than IP67. That your fish finder is waterproof does not mean you should blast it with water from a high-pressure hose. Also, ensure that the plugs are shielded from water and dust.

Supported Frequencies

As reiterated several times, fish finders utilize sonar (ultrasonic) technology in detecting the movement of fish. Fish finders can utilize different ranges of ultrasonic frequencies. Ultrasound frequency ranging from 15kHz, up to 200kHz can be utilized by most fish finders.

Although some special fish finders can use up to 400kHz. The choice of frequencies to be used by the angler depends solely on the purposes which could include finding a specific fish species, carrying out a wide search of the area, detecting shoals of fish, etc. The range of the fish finder is dependent on the frequency used.

For example, a deep-water search would require a low frequency, though they are not the best for a well-detailed study of the environment whereas a search into shallow water needs a high frequency. Experts and commercial fishers utilize the characteristics of the various frequencies of the fish finder in yielding the best fishing experience.

In searching, they use a low frequency, say 15kHz, which can orientate them about the general location of the schools of fish. They then switch to the higher frequencies when they need to get an exact location and are ready to target a school.

GPS Included

The GPS is not really that important to be part of your fish finder. Some want their fish finder to be more than just a tool for finding fish. They want it to also serve as a tool for navigation. The fish finder and GPS combo are actually good as it makes you able to monitor the fish and the structure below your kayak.

Knowledge of what is below your kayak can help determine your direction through fishing and kayaking also helps you monitor your speed. The combo allows a split-screen that enables you to use both the fish finder and the GPS navigation system at the same time. The GPS-enabled fish finder may serve as an important safety tool, especially in emergency conditions.

They may be necessary for emergency conditions, especially for anglers fishing in unfamiliar locations. Or in cases where users get lost, rescuers would be able to locate them. When fishing in large water bodies, say an ocean or a sea, for example, the GPS-enhanced fish finder might be a must-have kayak fishing equipment.


One important part of your fish finder is the transducer as it is what determines what is underwater. The transducer makes you know if what you are picking underwater is a fish and not just vegetation, or even a landscape. The transducers are able to scan through the water under your kayak, and then send signals to the display unit of your fish finder.

They don’t just tell you the location of the fish but also tell you how deep the water is. Some new kayak designs now come with specially designed transducer scuppers. The scupper holes are made larger to contain the transducer which makes the installation of the transducer to kayaks very easy and quick.

Also, they ensure that your transducer would always be in water providing the best view. In older kayak models, the specially designed transducer scupper may be absent, which means you probably have to put your kayak in the hull of your kayak. All you need to do is just ensure that there are no air bubbles under your transducer as they may affect the image displayed.

Power Source

There are four main specs to look out for in deciding on a battery to choose for your fish finder. These are the battery construction, the power capacity, the size, and then we have the weight. All of these specs have to be considered carefully before making a choice.

  • Battery Construction

There are different kinds of batteries, but only two types are suitable for fish finders. The reason for this is not far-fetched, it is because of the marine environment, where the batteries are to be used. These two batteries, the Sealed Lead Acid batteries (SLA) and the Lithium Batteries (LIFEPO4) are designed in such a way that can handle the harsh conditions and the constant motion that would be experienced during use.

Sealed Lead Acid Batteries (SLA): These are the kind of batteries we found in watercraft, they can adapt well irrespective of their orientation. As the name indicates, they are sealed, with no risk of spillage. They come in very cheap, though they are somewhat heavy. The SLA can function well irrespective of the temperature condition, although they shouldn’t be used past the 50% battery capacity, using the capacity past the halfway mark, you risk the durability of the battery.

Lithium Batteries (LIFEPO4): Lithium batteries are definitely the best choice of batteries you can use to power your device. They are lightweight, no worry of your battery being an added weight as in the SLAs, you can also use up the whole power without any risk of durability. The only downside I can think of about this battery is the price. The LIFEPO4 is on the dear side.

  • Battery Size and Weight

As size and weight mostly go hand in hand, I decided to combine these two specs as one. Since these batteries are to be used in powering a fish finder on a kayak, you probably don’t want too much weight to paddle during your journey. And since there are only two options available to us, I believe it isn’t a difficult one, especially if cost isn’t an issue.

The Lithium batteries appear to be the smaller and lighter of the two options. They also have the great capacity as the SLAs One thing to note is that these batteries like other battery types come in sizes, so what size would be the most ideal for your kayak? The size you will need for your fish finder depends on the current draw of your device. All you have to do is check through the specifications of your kayak, you should see a label indicating ‘current draw’, which is always measured in milliamperes(mA).

For most fish finders out there, their current draw is 250mA, with this, identifying the size of battery most suitable for your fish finder becomes the least of your problems. The battery capacity is usually measured in Amperes Hours(Ah), so for example, a battery rated 12Ah, should serve you at a rate of 1amps for 12 hours, or 12 amps for 1 hour.

As earlier stated, most fish finders have a current draw of 250mA. This means that if we planned on fishing for say 4 hours using this type of fish finder, we would use up a battery of 1Ah for the 4hours schedule.

Final Thoughts

Fish finders can improve your fishing experience by directing you to the best fishing spots and this will massively improve your chances of catching fish. Fishing is only fun if you are able to catch fish and a fish finder might be what you need to redefine your fishing experience.

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