You should know how a fish finder operates before making a choice.
Fishfinders use sonar technology to find fish-or any other solid object-under the surface of the water. Sonar sound waves travel through the water. As they travel further, the sound wave will increase in diameter, going from the point of initiation and fanning out into a cone-like shape. The cone naturally becomes larger in deeper water because it continues to fan out from the point of origin. As the sound wave hits a solid mass it will echo back to the transducer. The time difference between when the sound bounces back from an object and it’s surrounding area determine the shape and size. That shape will then appear on your fishfinder screen and you will be able to see a proximation of what the object looks like.
Your budget will likely be the next determining factor in your choice. Figure out how much you would really like to spend on a fish finder. Then multiply that times two. That will give you a more realistic budget to work with.
Naturally, the budget isn’t the only consideration. There are six other significant factors to help you to make the best choice for you. Consider each of the following:
Each fishfinder is rated for a particular depth. The rating will indicate how far down the signal will return effective soundings based on the intensity of the signal. You should first realize that the ratings are for ideal conditions in clear fresh water unless stated otherwise. When fishing in salt or murky water the effective depth will be less than stated. Like everything else; the more power the higher the cost; so know that if you plan to fish really deep water you need to spend more.
A good rule of thumb and my recommendation is to purchase a fishfinder with a rating of 10% more than you plan to need.
You should check included accessories for your fishfinder diligently before you make your purchase. Some do not come with a transducer and you will need to purchase one separately. That will make a difference in the overal price. The two types of transducers are single frequency and dual frequency. You may require one, the other or both depending on for what and where you are fishing. Single frequency transducers work best in shallow coastal waters or inland lakes. A duel frequency transducer is recommended for deep sea and offshore fishing. A transducer with dual frequency gives you a higher frequency transducer for a smaller cone in deep water. As an example; a 50kHz frequency transducer could have a 4 degree cone to provide a good view of the bottom in deep water and 200kHz transducer with a 20 degree cone would provide a better view of the bottom in shallower water. You need to purchase the correct transducer, because both will generate information on your screen, but you want the information to be accurate.
Installation of the unit must also be factored in here. You need to know if you plan to mount the fishfinder on a single boat and leave it there or if you prefer the flexibility of being able to take it with you and use it on a friend’s boat, as well. Also, you need to decide if you will mount it on the transom or go through the hull for optimum clarity.
Several companies make single frequency ducers. Each of these units is best suited for use on a small boat. They are intended for use on rivers, streams, or inland lakes.
A transom mount unit is usually easier and less expensive to install. You can purchase transom mounts in both single frequency and dual frequency fishfinder models. Transom mounts are best for use in water that will not be very disrupted by a boat moving fast.Clarity usually is affected once your boat reaches 10 knots.
Through hull transducers, on the other hand, are ideal for performance and clarity. However, this requires another hole in the bottom of the boat. But they are needed if you want clarity at high speeds.
My recommendation is to purchase a through-the-hull mounted transducer with dual frequency only if you are planning to fish in very deep waters-either fresh water or salt water.
Smaller boats fishing relatilely shallow water at slow speed can use a portable or transom mount. The money you save will be better served by using it to fill up your boat’s gas tank!
As a rule, more power is always a good thing. When comparing units that are equal in all other features, the cheaper unit will almost always have less power. However, power is the key to accuracy and clarity because that is what determines the speed of the sonar echoes (bounced back sound waves) reaching your unit.
After finding all other factors equal I recommend buying the unit with the highest power rating. In other words, consider units that have everything you want and then compare the power rating of all of those units to see which one has the highest power rating.
DISPLAY – SCREEN AND RESOLUTION
Consider this when looking at different options for the display. Color screens are easier to view in bright sunlight. A clearer image will be produced with higher resolution.
We recommend you research several units in your price range then choose the one with the highest resolution and a color screen. 480×480 is ideal, but you don’t want to go any lower than 320×240.
DISPLAY – SIZE
Like more power being better, when it comes to display size, bigger is always better-if it fits where you want to put it! So before you can really determine the ideal display size for you, you need to measure the area where you will install the display unit. That will dictate the largest display screen you can purchase. Just like more power, a bigger screen will fetch a heftier price. But display size isn’t absolutely everything. A few really good fish finders have a 4″ screen.
READ THE REVIEWS, BUT . . .
When reading the fish finders reviews be somewhat skeptical of exagerated claims of performance! There isn’t likely anyone who has actually owned and used all of the different model they write about. More than likely the writer works for a manufacturer or distributor. It’s best to look for technical differences rather than praise of performance. For instance, eFishBox.com has a fishfinder review page that shows the specifications of all of the fishfinders produced by the industry brand name leaders so you can make real comparisons based on the actual features. Make your decision based on your requirements and a solid understanding of the features you need, not someone who is getting paid to endorse a particular product.