Echo Sounder
Q: What can an echo sounder do for me?
Q: What things should I consider when looking for a new echo sounder?
Q: How does an echo sounder work?
Q: How will my echo sounder differentiate between echoes of different strengths?
Q: Should I get an LCD or a CRT echo sounder?
Q: Why are some echo sounders dual frequency?
Q: Can I interface my echo sounder with other marine electronics equipment?
Q: What can an echo sounder do for me?
A: An echo sounder can help you with the following: Locating where schools of fish are hiding around a structure and their depths. Locating shipwrecks, reefs, pinnacles, sunken trees and other objects between the hull of the vessel and the bottom. Determining bottom contours and composition to recognize soft mud, gravel, sand and rock. Determining the water depth and locating hazards for navigation purposes. Determining the location of areas where the temperature of the water changes dramatically. Determining what species of fish are being shown on the echo sounder display. (An experienced operator can determine what species of fish are being displayed by their different shapes and the size of the air bladders in the fish, a trait that shows up well on high quality echo sounders. Other factors such as water temp, water depth and schooling characteristics will help determine fish species.)
Q: What things should I consider when looking for a new echo sounder?
A: Choosing which echo sounder is right for you can sometimes be confusing. Knowing some basic information about your vessel and what your needs are will help this process. First you need to determine how you plan on using your echo sounder. For example, do you plan on using it mostly for fishing, navigation or a combination of the two. It will also help if you know approximately the depth of water where you will be using the sounder. This will help you and your Furuno dealer determine the power output level needed on your new sounder. Once you determine how it will be used, you need to decide where the sounder will be installed. Where you mount the sounder plays an important role in the type of display you should get. Sunlight washing out the display may not be a concern if it is mounted in a covered area, but if it is mounted in direct sunlight you will probably want a high contrast LCD display that will not wash out. Also, if it is mounted in the open, you will want a sounder that has a waterproof case so that the internal circuitry will not get damaged from water spray. Determine what type of power input will be use when the sounder is installed. Furuno sounders are available in a variety of power inputs, including 12VDC, 24VDC, 32VDC, 110VAC and 220VAC. Finally, you should consider where you want to mount the transducer for optimum performance and minimal interference. For more information on transducers, visit our informative page on transducers.
Q: How does an echo sounder work?
A: Echo sounders determine the distance between its transducer and underwater objects such as fish or seabed and show the results on the display. An ultrasonic wave transmitted through water travels at a nearly constant speed of 4800 feet (1500 meters) per second. When a sound wave strikes an underwater object such as fish or sea bottom, part of the sound is reflected back toward the source. The depth to the object can be determined by calculating the time difference between the transmission of a sound wave and the reception of the reflected sound. The sounder will then display this return as one of up to 16 different colors (color sounder) or a different level of gray scaling (monochrome sounder) depending on the strength of the returned signal.
Q: How will my echo sounder differentiate between echoes of different strengths?
A: A color echo sounder will use a different color for any one of up to 16 different signal strengths. This will make your strong returns show up as red and your weaker colors as green or blue. Monochrome sounders will use different levels of gray to show the different levels of signal strength. Strong returns such as a hard bottom will show up as a very dark color and items such as debris in the water or concentrations of plankton will appear as a cloudy gray.
Q: What is “white line”?
A: Some color sounders have a feature called “white line,” which allows an operator to replace any color or strength level with the color white. The color white tends to stand out from the rest of the colors on a sounder display, which will aid an operator who is looking for a specific level of echo return, such as bait or individual fish.
Q: What is a transducer?
A: The major function of the transducer is to convert electrical energy from the transmitter into sound/mechanical energy. The transducer then picks up the sound after it reflects off of the object. The transducer is one of the most important parts of an echo sounder system, and it is sometimes the most neglected. The transducer can be compared to the speakers of a stereo system. A high quality speaker placed in the ideal location will deliver the best results. The same is true with transducers.
Q: Should I get an LCD or a CRT echo sounder?
A: There are two display types to choose from, CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display.) Each type has different advantages that need to be considered when choosing an echo sounder. A CRT is similar to a television screen. It has high contrast in normal to low light, allowing for bright and clear targets to be shown on the display. Bright sunlight will tend to make the CRT display fade. CRT echo sounders work best in an environment that is either covered or out of direct sunlight. With echo sounders, color units allow you to discriminate easier between small differences in signal returns.
Q: Why are some echo sounders dual frequency?
A: When acoustic energy travels through the water, the frequency of that energy determines how deep it will travel and also the level of definition you can expect to see after it has bounced off of an object below. The lower frequencies, (50 kHz) provide better ground discrimination and also detect fish better in deeper water. The higher frequencies, (200 kHz) will detect fish such as mackerel and squid with no swim bladders easier and usually provide better discrimination between schools of fish and individual large fish. Having a dual frequency echo sounder gives you the advantage of having a deep penetrating lower frequency and a high definition higher frequency.
Q: Can I interface my echo sounder with other marine electronics equipment?
A: Yes. All Furuno echo sounders will accept electronics navigation information from GPS or LORAN. In addition, your Furuno echo sounder will output depth, and in some cases, temperature to any device that will accept it. (Optional interconnect cables may be required.) This will allow you to display your depth information where your GPS/Plotter is, as well as displaying your LAT/LON at the location where your sounder is.