Before you can decide which fishfinder is the best one for you, you should know how a fishfinder performs.

Fishfinders use sonar technology to locate fish-or any other solid object-under the surface of the water. Sonar sound waves move through the water. The farther the sound waves travel, the more they fan out into a cone shape and increase in diameter. Deeper water naturally causes the cone to become larger as it moves from it's origin. Whenever the sonar wave strikes against a solid object of any substance, it will bounce an echo back to the transducer. The shape of the object struck will be determined by how long it took the signal to go out and then bounce the sound wave echo back compared to the surrounding area. The echo will then appear on your fishfinder screen and you will see the aproximate size, shape and depth of the object.

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 double that. This is more realistic and helps set an actual budget to work with.

Naturally, the budget isn't the only consideration. There are six other significant factors to help you make the best choice for you. Review all of the following:

DEPTH RATING

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. However, you should know that the depth ratings given are for ideal circumstances in fresh, clean, relatively clear water; unless it states otherwise. When fishing in salt or murky water the effective depth will be less than stated. As with most other things, however, if you want a unit that will penetrate deeper water, that unit is going to cost more.

My recommendation is to purchase a fishfinder unit that has a depth of at least 10 percent more than what you think you will actually need.

IS THE TRANSDUCER INCLUDED?

One needs to check the packaging for your fishfinder carefully before makinf a purchase. Some fish finders come without a transducer so you need to check the included accessories before purchasing. So consider that in the overall 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. For instance, a 50 kHz frequency fishfinder could have a 4 degree cone that goes deep down and provides a good view of the bottom whereas a 200 kHz frequency fishfinder with a 20 degree cone would provide a good 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. Another consideration is portability; will you leave it on one boat or move it from boat to boat. 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.Most of these units are intended for use on smaller boats. They are intended for use on rivers, streams, or inland lakes.

A transom mount unit is usually easier and less expensive to install. Trasducers can be purchased in both single and dual frequency fish finder models. A fast moving boat will cause disrupted water at the transom and affect the use of a transom mount.Clarity usually is affected once your boat reaches 10 knots.

Through hull transducers, on the other hand, are ideal for performance and clarity. But this does require putting another hole in your boat hull for installation. And they are really only warranted if you need bottom reading at very high speeds.

Through the hull dual frequency transducers are recommended if you plan to fish deep water and need to read the fish at high speeds.

For anyone who has a small boat or won't be fishing at really high speeds, go with a portable unit or a transom mount. The money you save will be better served by using it to fill up your boat's gas tank!

POWER CONSIDERATION

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. For the best accuracy and clarity go for the high power as that is what determines the speed of the sonar return signals.

My recommendation is to purchase the highest power rating you can afford with all other factors being equal. 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

When you are looking at the different options for the display, consider this. Color screens are easier to view in bright sunlight. Also, the higher the resolution, the clearer the image you will see on the screen.

My recommendation is to look at several units in your price range with the features you want and then purchase the unit with the higher screen resolution, in color. 480x480 is ideal, but you don't want to go any lower than 320x240.

SIZE OF DISPLAY

Similar to power, a larger screen will be better as long as it will fit where you want 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 give you the largest display unit you can purchase. A bigger screen will equal a heftier price, of course. But display size isn't absolutely everything. Some really great fishfinders have 4" diagonal screens and work fantastic.

READ THE REVIEWS, BUT . . .

It's one thing to read the fishfinder reviews out there, but hey, take them with a huge grain-or maybe a block-of salt! 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. Instead, look for unbiased sources that present the actual facts. 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.