Cabin display of a commercial or oceanographic fathometer sonar

Discover the great deals on top brand fishing equipment available only on eBay!

Fishfinders

A fishfinder is a type of Fathometer, both being specialized types of echo sounding systems, a type of Active SONAR. ('Sounding' is the measurement of water depth, a historical nautical term of very long usage. more...

HomeHome
Apparel & FootwearApparel & Footwear
DecalsDecals
Downrigger, Outrigger GearDownrigger, Outrigger Gear
FishfindersFishfinders
Fly FishingFly Fishing
FreshwaterFreshwater
Ice FishingIce Fishing
Other New & Used ItemsOther New & Used Items
Rod Building & RepairRod Building & Repair
SaltwaterSaltwater
Tackle BoxesTackle Boxes
Terminal TackleTerminal Tackle
VintageVintage

) The fishfinder uses active sonar to detect fish and 'the bottom' and displays them on a graphical display device, generally a LCD or CRT screen. In contrast, The modern fathometer (from fathom plus meter, as in 'to measure') is designed specifically to show depth, so may use only a digital display (useless for fish finding) instead of a graphical display, and frequently will have some means of making a permanent recording of soundings (which are merely shown and subsequently electronically discarded in common sporting fishfinder technology) and are always principally instruments of navigation and safety. The distinction is in their main purpose and hence in the features given the system. Both work the same way, and use similar frequencies, and, display type permitting, both can show fish and the bottom. Thus today, both have merged, especially with the advent of computer interfaced multipurpose fishfinders combining GPS technology, digital chart-plotting, perhaps Radar and electronic compass displays in the same affordable sporting unit.

Operating theory

In a generalized sense, an electrical impulse from a transmitter is converted into a sound wave by the transducer, called a hydrophone, and sent into the water. When the wave strikes something such as a fish, it is reflected back and displays size, composition, and shape of the object. The exact extent of what can be discerned depends on the frequency and power of the pulse transmitted. The signal is quickly amplified and sent to the display. Knowing that the average speed of the wave in the water is 4800 ft/s (1500 m/s) in seawater, 4708 ft/s (1435 m/s) in freshwater, both at normalized temperatures, the distance to the object that reflected the wave can be determined. The process can be repeated up to 40 times per second and eventually results in the bottom of the ocean being displayed versus time (the fathometer function that eventually spawned the sporting use of fishfinding.) Note: This discussion of the propagation of sound in water is simplified, speed of sound in water depends on the temperature, salinity and ambient pressure (depth). This follows approximately this formula (del Grosso, 1974):
c = 1448.6 + 4.618T − 0.0523T2 + 1.25 * (S − 35) + 0.017D
where
c = sound speed (m/s)
T = temperature (degrees Celsius)
S = salinity (pro mille)
D = depth
This will give variations in speed through the water column

General interpretation

The image above, at right, clearly shows the bottom structure -- plants, sediments and hard bottom are descernible on sonar plots of sufficiently high power and appropriate frequency. Slightly more than halfway up from the bottom to the left of the screen center and about a third away from the left side, this image is also displaying a fish -- a light spot just to the right of a 'glare' splash from the camera's flashbulb. The X-axis of the image represents time, oldest (and behind the soundhead) to the left, most recent bottom (and current location) on the right; thus the fish is now well behind the transducer, and the vessel is now passing over a dip in the ocean floor or has just left it behind. This obviously depends on both the speed of the vessel and how often the image is updated by the echo sounder.

Read more at Wikipedia.org


[List your site here Free!]

Propeller Tool/BoatsPropeller Tool/Boats $13.98 Lowrance 000-12635-001 Hook-3X Sonar, W/ 83/200 XdcrLowrance 000-12635-001 Hook-3X Sonar, W/ 83/200 Xdcr $128.95
Seaw-Hum4103901-Solix 12, 12.1" Plotter/Chirp SounderSeaw-Hum4103901-Solix 12, 12.1" Plotter/Chirp Sounder $2,459.23 Fish Finder Gps Combo Depth Finder Sonar Marine Navigation Tools Garmin NewFish Finder Gps Combo Depth Finder Sonar Marine Navigation Tools Garmin New $173.80
New Fish Finder Underwater Fishing 4.3" Tft Lcd Monitor + 20m Cable Night VisionNew Fish Finder Underwater Fishing 4.3" Tft Lcd Monitor + 20m Cable Night Vision $78.84 List price:  Previous Price $149.99 Seaw-Hum4102901-Combo, Helix 7 Chirp Gps G2Seaw-Hum4102901-Combo, Helix 7 Chirp Gps G2 $477.17
Garmin Striker 5 Ice Fishing Bundle 010-01552-10Garmin Striker 5 Ice Fishing Bundle 010-01552-10 $399.98 List price:  Previous Price $399.99 Cwre-25027-Lowrance Dual Frequency Tm TransducerCwre-25027-Lowrance Dual Frequency Tm Transducer $100.21
Fishing Video Camera Waterproof 12Pcs Led Fish Finder Fish Alarm 15m/30m R2I3Fishing Video Camera Waterproof 12Pcs Led Fish Finder Fish Alarm 15m/30m R2I3 $54.18 to $64.63 Was:  Previous Price $57.03 Eyoyo 50m Infrared Light 7" Lcd Fish Finder Underwater Camera w/Lights ControlEyoyo 50m Infrared Light 7" Lcd Fish Finder Underwater Camera w/Lights Control $145.68
New! WiFi P2P wireless underwater fish finder App visual fishing camera systemNew! WiFi P2P wireless underwater fish finder App visual fishing camera system $99.33 Was:  Previous Price $129.00 Humminbird 409830-1 Helix 7 Di Gps/Fishfinder With Down Imaging SonarHumminbird 409830-1 Helix 7 Di Gps/Fishfinder With Down Imaging Sonar $1,108.28
HawkEye DepthTrax 1BHawkEye DepthTrax 1B $93.37 Humminbird Transom Mount Transducer Depth/Temp Xnt 9 20 T 200/83 710198-1Humminbird Transom Mount Transducer Depth/Temp Xnt 9 20 T 200/83 710198-1 See details... $79.99
Lowrance Hook 3X Sonar Fish Finder Depth Finder Marine Navigation Tool XdcrLowrance Hook 3X Sonar Fish Finder Depth Finder Marine Navigation Tool Xdcr $133.18 Nova-Cwr25033-Lowrance Transom Mount 20 Degree Skimmer WithNova-Cwr25033-Lowrance Transom Mount 20 Degree Skimmer With $98.58
Raymarine Rv-300 RealVision 3D Plastic Through Hull Transducer 8m Cable A80470 #Raymarine Rv-300 RealVision 3D Plastic Through Hull Transducer 8m Cable A80470 # $823.87 Underwater 1000Tvl Fishing Video Camera Led Fish Finder Detector 15m/30m L4L4Underwater 1000Tvl Fishing Video Camera Led Fish Finder Detector 15m/30m L4L4 $54.14 to $64.59 List price:  Previous Price $79.99
7" Lcd Monitor 30M Underwater Fish Finder Hd 1200Tvl Camera for Fishing Us G3S97" Lcd Monitor 30M Underwater Fish Finder Hd 1200Tvl Camera for Fishing Us G3S9 $103.39 Humminbird 409600-1 Helix 5 Di Fish Finder With Down ImagingHumminbird 409600-1 Helix 5 Di Fish Finder With Down Imaging $648.38
Raymarine Rmx8Bb Black Box and Pmxcan Transceiver Topfil #64520248Raymarine Rmx8Bb Black Box and Pmxcan Transceiver Topfil #64520248 $513.52 Portable Dot Matrix Lcd Fish Finder Rechargeable Wireless Sonar Sensor Vs U1N2Portable Dot Matrix Lcd Fish Finder Rechargeable Wireless Sonar Sensor Vs U1N2 $72.95
Eyoyo 3.5" Monitor Hd 1000Tvl Camera 15M Fish Finder Ice/Sea/River FishingEyoyo 3.5" Monitor Hd 1000Tvl Camera 15M Fish Finder Ice/Sea/River Fishing $91.08 Raymarine Axiom 7Dv 7" Multifunction Display with Fishfinder DownVision TransducRaymarine Axiom 7Dv 7" Multifunction Display with Fishfinder DownVision Transduc $1,293.54
Seaw-Low00012570001-Xdcr, Hdi Tm, Mid/Hi/455/800, 9 PinSeaw-Low00012570001-Xdcr, Hdi Tm, Mid/Hi/455/800, 9 Pin $126.72 7" Color Monitor 1000Tvl Underwater Fishing Video Camera Kit 6 Pcs Led Lights7" Color Monitor 1000Tvl Underwater Fishing Video Camera Kit 6 Pcs Led Lights $104.39 to $113.67 Was:  Previous Price $179.99
Humminbird Plastic Thru Hull Transducer Xpth 9 Hdsi 710210-1Humminbird Plastic Thru Hull Transducer Xpth 9 Hdsi 710210-1 $189.47 List price:  Previous Price $279.99 Hd Fishing Video Camera 1000Tvl 12 Led Fish Finder Fishing Alarm 15m/30m Q2Q7Hd Fishing Video Camera 1000Tvl 12 Led Fish Finder Fishing Alarm 15m/30m Q2Q7 $58.99 to $73.95 List price:  Previous Price $69.99
New! Humminbird Speed and Temp Temperature Sensor Ts-W Hummingbird 730000-1New! Humminbird Speed and Temp Temperature Sensor Ts-W Hummingbird 730000-1 $39.95 Vexilar Sp200 T-Box Smartphone Fish Finder, BlackVexilar Sp200 T-Box Smartphone Fish Finder, Black $185.41
Seaw-Ga0101107801-Nmea 2000 Multiport T-Connector, 4 PortSeaw-Ga0101107801-Nmea 2000 Multiport T-Connector, 4 Port $64.12 Camelion Battery Cannon Deck Plate Mb 2200693Camelion Battery Cannon Deck Plate Mb 2200693 $42.33
Humminbird Idmk 1100 Dash Mount for 1100 Series FishfindersHumminbird Idmk 1100 Dash Mount for 1100 Series Fishfinders $39.57 *Untested* Eagle by Lowrance Mach 1 Computer Graph Fish Finder *Read**Untested* Eagle by Lowrance Mach 1 Computer Graph Fish Finder *Read* $35.08
Raymarine Axiom 9Rv 9" MultifunctionDisplay with Fishfinder & RealVision 3D E70Raymarine Axiom 9Rv 9" MultifunctionDisplay with Fishfinder & RealVision 3D E70 $1,943.56 Bottom Line Flasher Depth FinderBottom Line Flasher Depth Finder $13.50
Wireless Bluetooth Sonar Fishfinder Fishing Detector For Android Ios iPhone Luw0Wireless Bluetooth Sonar Fishfinder Fishing Detector For Android Ios iPhone Luw0 $1.05 to $63.89 Deeper Smart Portable Fish Finder (Depth Finder) For Smartphone Or Tablet, ForDeeper Smart Portable Fish Finder (Depth Finder) For Smartphone Or Tablet, For $222.95
Lowrance & Eagle Sx-12Bk Speed/Temp Extension CableLowrance & Eagle Sx-12Bk Speed/Temp Extension Cable $19.95 Hd 600 Tvl 7" Tft Color Lcd Underwater Fishing Camera Fish Finder 50M Cable DvrHd 600 Tvl 7" Tft Color Lcd Underwater Fishing Camera Fish Finder 50M Cable Dvr $387.99
Raymarine Axiom 9 9" Colored Multifunction Wifi Touch Display E70366 #64520676Raymarine Axiom 9 9" Colored Multifunction Wifi Touch Display E70366 #64520676 $1,618.55 Raymarine Axiom 9Rv 9" Multifunction Display + Fishfinder + RealVision 3D + TranRaymarine Axiom 9Rv 9" Multifunction Display + Fishfinder + RealVision 3D + Tran $2,008.57
Eyoyo 50M Cable Underwater Fishing Camera Ice/Boat Fish Finder 9" Hd 1000Tvl LcdEyoyo 50M Cable Underwater Fishing Camera Ice/Boat Fish Finder 9" Hd 1000Tvl Lcd $176.99 Raymarine Rmx5 2.7" Colour Display for Digital Multimedia Receiver + Pmx-Can StRaymarine Rmx5 2.7" Colour Display for Digital Multimedia Receiver + Pmx-Can St $643.52
Raymarine Axiom 7 7" Multifunction Display E70363 #64520660Raymarine Axiom 7 7" Multifunction Display E70363 #64520660 $968.53 30M 1200Tvl Fish Finder Underwater Ice Fishing Camera 7" Color Hd Monitor U1L830M 1200Tvl Fish Finder Underwater Ice Fishing Camera 7" Color Hd Monitor U1L8 $103.20
New arrival! WiFi wireless underwater fishing camera system Smartphone App viewNew arrival! WiFi wireless underwater fishing camera system Smartphone App view $99.33 Was:  Previous Price $129.00 Seaw-Low00011517001-Fuel Flow Sensor PackSeaw-Low00011517001-Fuel Flow Sensor Pack $199.00
Raymarine Axiom 7Dv 7" Multifunction Display with Fishfinder + Downvision + CartRaymarine Axiom 7Dv 7" Multifunction Display with Fishfinder + Downvision + Cart $1,228.54 Dot Matrix Lcd Display Fish Finder with Sonar Sensor 90 degree Sonar Beam Qyx2Dot Matrix Lcd Display Fish Finder with Sonar Sensor 90 degree Sonar Beam Qyx2 $1.05 to $63.85
Outlife Smart Fish Finder with Wireless Sonar Sensor Lcd DisplayOutlife Smart Fish Finder with Wireless Sonar Sensor Lcd Display $53.33 Lowrance-Eagle Xd-2 (40-91) Transducer-Transom Mount-20 Degree-192Khz.Lowrance-Eagle Xd-2 (40-91) Transducer-Transom Mount-20 Degree-192Khz. $29.50
Raymarine Pole Mount f/Rs150 Gps AntennaRaymarine Pole Mount f/Rs150 Gps Antenna $27.25 iBobber Wireless Bluetooth Smart Fish Finder For iOs & Android DevicesiBobber Wireless Bluetooth Smart Fish Finder For iOs & Android Devices $116.04
Raymarine Rv-100 RealVision 3D Transom Mount Transducer A80464 #64520750Raymarine Rv-100 RealVision 3D Transom Mount Transducer A80464 #64520750 $513.52 Seaw-Hum7800331-Suncover, PiranhaMax 4Seaw-Hum7800331-Suncover, PiranhaMax 4 $34.16
Kkmoon 7" Monitor 1200Tvl Camera Underwater Fish Finder System 30m Cable Us D5C3Kkmoon 7" Monitor 1200Tvl Camera Underwater Fish Finder System 30m Cable Us D5C3 $103.25 Raymarine Axiom 12 12" Multifunction Display with Cartography E70368-00-Nsd #645Raymarine Axiom 12 12" Multifunction Display with Cartography E70368-00-Nsd #645 $3,503.62
Wint-Hum7102111-Humminbir d Xi-9-20 Transducer Ice MountWint-Hum7102111-Humminbir d Xi-9-20 Transducer Ice Mount $88.26 Humminbird Xpth 14 74 T Dual Beam Through Hull TransducerHumminbird Xpth 14 74 T Dual Beam Through Hull Transducer $181.78
Raymarine Universal Usb and Aux input Jack #64520243Raymarine Universal Usb and Aux input Jack #64520243 $58.50 Humminbird Ice 45 Ice Fishing Flasher 1800 WattsHumminbird Ice 45 Ice Fishing Flasher 1800 Watts $419.97
Raymarine Dragonfly 7 Pro with Navionics+ North America ChartsRaymarine Dragonfly 7 Pro with Navionics+ North America Charts $525.00 4.3" Hd Tft Lcd Monitor Screen Fish Finder Dvr Video Led Fishing Camera X0E94.3" Hd Tft Lcd Monitor Screen Fish Finder Dvr Video Led Fishing Camera X0E9 $94.99
Humminbird Transom Mount Transducer Nt 9 20 THumminbird Transom Mount Transducer Nt 9 20 T $68.77 Wint-Low00010976001-Lowra nce 000-10976-001 Skimmer Hdi 83/200 And 455/800KhzWint-Low00010976001-Lowra nce 000-10976-001 Skimmer Hdi 83/200 And 455/800Khz $121.64
Raymarine Rmx5 2.7" Color Display for Digital Multimedia Receiver #64520246Raymarine Rmx5 2.7" Color Display for Digital Multimedia Receiver #64520246 $513.52 Hd Fishing Video Camera 1000Tvl 12 Led Fish Finder Fish Sensor 15m/30m L3N6Hd Fishing Video Camera 1000Tvl 12 Led Fish Finder Fish Sensor 15m/30m L3N6 $55.95 to $69.37 Was:  Previous Price $58.89
Humminbird 7400721 Ms Ppm Portable Case Lock Down MountHumminbird 7400721 Ms Ppm Portable Case Lock Down Mount $25.98 Humminbird 409620-1 Helix 5 Di Fish Finder With Down-Imaging And GpsHumminbird 409620-1 Helix 5 Di Fish Finder With Down-Imaging And Gps $827.22
Humminbird Idmk700 Dash Mount for 500 and most 700 series FishfindersHumminbird Idmk700 Dash Mount for 500 and most 700 series Fishfinders $39.57 Seaw-Low00012240001-Elite -9 SuncoverSeaw-Low00012240001-Elite -9 Suncover $36.86
Raymarine Cpt-S Plastic Conical High Chirp Transom Mount Transducer E70342 #6452Raymarine Cpt-S Plastic Conical High Chirp Transom Mount Transducer E70342 #6452 $76.70 Venterior Portable Fish Finder, Fishfinder with Wired Sonar Sensor TransducerVenterior Portable Fish Finder, Fishfinder with Wired Sonar Sensor Transducer $51.03
Hd Fishing Video Camera 1000Tvl Lights Fish Finder Fish Inspection 15m/30m T7E3Hd Fishing Video Camera 1000Tvl Lights Fish Finder Fish Inspection 15m/30m T7E3 $55.07 to $69.32 Was:  Previous Price $57.97 Humminbird Ice-35 Dual Beam FlasherHumminbird Ice-35 Dual Beam Flasher $329.99
Stern Pad - Transducer Mounting Kit (Adhesive/No Screwing into Boat) - WhiteStern Pad - Transducer Mounting Kit (Adhesive/No Screwing into Boat) - White $29.99 Th Marine Em-1204 Aluminum Gps Phone Mount 3204Th Marine Em-1204 Aluminum Gps Phone Mount 3204 $29.79
Waterproof 30M Underwater Hd 1200Tvl Fish Finder Camera+7" Lcd Monitor Ip68 R4X4Waterproof 30M Underwater Hd 1200Tvl Fish Finder Camera+7" Lcd Monitor Ip68 R4X4 $103.50 Vexilar AlumaDucer Transducer w/summer kit for Fl12 & Fl20 Fish FindersVexilar AlumaDucer Transducer w/summer kit for Fl12 & Fl20 Fish Finders $199.00
Wifi Wireless 20M Underwater Fishing Camera Video Recorder (Syf001-2Om)Wifi Wireless 20M Underwater Fishing Camera Video Recorder (Syf001-2Om) $121.59 Was:  Previous Price $127.99 New Lowrance Navionics Msd/Hmpt-W6 HotMaps Platinum Sd/Msd WestNew Lowrance Navionics Msd/Hmpt-W6 HotMaps Platinum Sd/Msd West $189.99
Raymarine Prime M1 6.5” Coaxial/Component Speaker White #64520267Raymarine Prime M1 6.5” Coaxial/Component Speaker White #64520267 $188.51 Lowrance Castable Surface Portable Sonar FishHunter ProLowrance Castable Surface Portable Sonar FishHunter Pro $229.99
Raymarine Rmx1R Wired Remote 2.7" Color Display #64520244Raymarine Rmx1R Wired Remote 2.7" Color Display #64520244 $253.51 Humminbird Xpth 9 Di T Plasitc Thru Hull Transducer w/tempHumminbird Xpth 9 Di T Plasitc Thru Hull Transducer w/temp $199.99
Eyoyo 4.3" 20M 10pcs Ir Underwater Fishing Camera Fishfinder Black Color Lcd/LcdEyoyo 4.3" 20M 10pcs Ir Underwater Fishing Camera Fishfinder Black Color Lcd/Lcd $89.95 Raymarine Axiom 7Dv 7" Multifunction Display with Fishfinder DownVision & TransdRaymarine Axiom 7Dv 7" Multifunction Display with Fishfinder DownVision & Transd $1,202.54
Raymarine Axiom 7 7" Multifunction Display with Cartography E70363-00-Nsd #64520Raymarine Axiom 7 7" Multifunction Display with Cartography E70363-00-Nsd #64520 $1,033.53 Seaw-Ga0101109500-Nmea 2000 Field Connector, FemaleSeaw-Ga0101109500-Nmea 2000 Field Connector, Female $46.28
Lowrance 000-11030-001 Screen Cover for Hds-7 Touchscreen ModelsLowrance 000-11030-001 Screen Cover for Hds-7 Touchscreen Models $26.48 Humminbird Xb Ssi Side Imaging Tranducer (1 Pair) for Onix & IonHumminbird Xb Ssi Side Imaging Tranducer (1 Pair) for Onix & Ion $595.56
Humminbird Speed SensorHumminbird Speed Sensor $56.99 Outlife 0.7 - 100M Fish Finder 200Khz Sonar Sounder Alarm TransducerOutlife 0.7 - 100M Fish Finder 200Khz Sonar Sounder Alarm Transducer $33.87
Wint-Gar0100180900-Garmin Striker 7Sv 7" Color Fishfinder Gps Track PlotterWint-Gar0100180900-Garmin Striker 7Sv 7" Color Fishfinder Gps Track Plotter $434.43 iBobber Wireless Bluetooth Smart Fish Finder for iOs and Android Devices NewiBobber Wireless Bluetooth Smart Fish Finder for iOs and Android Devices New $118.70 Was:  Previous Price $124.95
Garmin 010-01808-00 Striker 7Cv with transducerGarmin 010-01808-00 Striker 7Cv with transducer $571.07 Raymarine Dragonfly 7Pro Display 7” with Navionics Gold Small 2 Cartography #645Raymarine Dragonfly 7Pro Display 7” with Navionics Gold Small 2 Cartography #645 $946.80
Hook-3X Dsi Sonar, w/ 455/800 XdcrHook-3X Dsi Sonar, w/ 455/800 Xdcr $112.83 Trending at $116.33 Eagle SupraPro Id Fish Finder Depth Finder and Case Freshwater Saltwater SupraEagle SupraPro Id Fish Finder Depth Finder and Case Freshwater Saltwater Supra $38.95
Click to see more Fishfinders items at www.ebay.com
Prices current as of last update, 01/19/18 7:47pm.

See also...

Home Contact Resources Exchange Links ebay