This page is about SONAR units.....also known as fish finders. For information on other marine electronics, visit
the Marine Electronics page.
Fish finders are essential equipment on fishing boats. They range from simple depth readouts to combination units that
can include mapping and navigational functions. Costs go up with features and can get into the thousands of US dollars.
In choosing a fish finder, you will need to decide on a budget. Next, consideration must be made to the
different types of display formats. Black and white is the simplest with other choices being grayscale (also known as monochrome) and color. Another choice is
the display type. Units can be any of several variations of LCD or they can use a CRT. LCD displays are are the same type commonly used on laptop computers. CRT
displays use a picture tube similar to a traditional television display. CRT displays are best suited for a sheltered environment such as an enclosed cabin.
The other choices all tend to boost the price, making a compromise inevitable if you have budget restraints.
Several factors determine the effectiveness of the fishfinder. When shopping, consider the following parameters:
-
viewable display size
-
display physical type (CRT
or LCD)
-
display format type
(monochrome or color)
-
resolution in pixels
-
single or dual transducers
-
transducer frequency
-
output power measured in RMS
-
temperature probe
The chart below may help sort out some
of the choices to be made
Fish Finder Feature
|
Advantages
|
Disadvantages
|
|
LCD Display |
typically cheaper
more waterproof
less fragile |
|
|
CRT Display |
good picture |
prone to breakage,
water damage |
|
Black and White Display |
inexpensive |
no longer produced? |
|
Monochrome or Grayscale display |
good picture
viewable in direct sunlight
less expensive |
does not
differentiate targets as easily as color displays |
|
Second Generation Grayscale "Blue Screen" display |
good picture
viewable in direct sunlight |
sometimes expensive |
|
Color Display |
excellant at
defining different targets |
difficult to see in
bright sunlight
expensive |
|
Second Generation Color
Display |
excellant at
defining different targets
viewable in direct sunlight |
expensive |
|
Temperature Probe |
important fish finding tool |
sometimes an added expense |
|
50 KHz Transducer |
good resolution
essential for deep saltwater |
narrow beam misses
fish
interference in shallow water |
|
200 KHz Transducer |
excellant wide
coverage |
poor results in
deep water |
|
50 KHz / 200 KHz Transducer |
best of both types! |
high initial cost |
Pages on Identifying Targets with Fish Finding Equipment
Shipwrecks, Reefs and Structure
Identifying Various with Fish Finding Equipment
More fish finder links
Installing a Fish Finder
See The Bottom Of The Lake in 3D
Humminbird 937
fish-finder-review.com
Transducer Directory
Related links
Shipwrecks and Artificial Reefs of Maryland and Virginia
Books about Local Shipwrecks
Wreck Fishing
Marine Electronics