Fish finder jargon explained

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Welcome to my jargon busting guide to fish finders.

I'll start by saying that there are quite a few brands of fish finder available but the technology is all based on similar principles. Each manufacturer uses their own terminology so some interpretation may be needed at times.

There are two main groups of fish finder with several subgroups.

Traditional sonar
This is non imaging sonar. The frequencies usually range from 50kHz to 300kHz.
The lower frequencies work deeper but the resolution is lower and you've guessed it, the higher frequencies work better in the shallower areas and give better resolution. Some units have two or more frequency ranges.
Fish are represented as arches or a fish symbol with this sort of fish finder. 
The view is usually as though you are looking in through the side of an aquarium.

Imaging sonar
This group of fish finders comes in a few different flavours;
Down scan (DSI) this type of sonar operates at higher frequencies 400kHz to 1000kHz.
It tends to work well at shallower depths and is great for showing bottom detail such as rock outcrops, vegetation etc. The images displayed are often described as almost 'photo like'. Fish do not appear as arches but are instead dispelled as they are. This can result in a smaller target than with traditional sonar. The view orientation is again like looking into the side of a fish tank.
Side scan sonar. This sort of sonar is very similar to down scan except that the view is as if you are looking down from above. There is a little bit of interpretation needed as the water column and anything swimming in it is also shown flattened out. One you get used to it this type of sonar gives great results and is aimed at the more serious fisherman. This system is often double the cost of Downscan.
Hybrid sonar. This is a mixture of traditional sonar and down scan. This gives the best of both worlds as the fish show up as arches and the bottom detail is very accurate. The transducers tend to be much bigger as both technologies have to be incorporated.

Screen size
Screens start at around 4" diagonal and commonly go to 7" diagonal although if you pockets are deep enough 16" is about the maximum at the moment. Screen quality is far better than it used to be so small screens do work quite well. The rule of thumb, try to choose a screen that fits your boat and your budget.

Colour or grayscale
This is personal choice. The grayscale screen can be easier to read but more detail is available with colour. If you can afford colour and you find that grayscale would be handy, don't worry as most of the colour screen can be set to grayscale.

I hope this guide has been helpful. I do intend to add more detail as time allows but if you want to know anything specific please feel free to ask.
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