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Furuno LS6100

The Furuno LS6100 has been proving itself a viable performer as a member of the Furuno fishfinder lineup for nearly a decade. As an entry level 300-watt dual frequency monochrome fishfinder this unit has been a reliable fishfinder even as it faced newer competition. I reviewed this Furuno fishfinder several years ago and thought is was time to revisit.

Buy this Furuno fishfinder here.

The LS6100 display unit has a nearly square panel front that measures 7.7 inches high and 7.2 inches wide, depth is 3.3-inches. The unit ships with the display unit, power cable, owner’s manual, beefy tilt-only mounting bracket, protective front cover, and hardware to flush mount the display.

furuno ls6100 fishfinder sounder

Furuno LS6100

All essential electronics are internal to the display. The only remaining component needed get full use out of this bottom machine is a transducer.

Several transducer options are available ranging from plastic transom-mount units with water temperature sensing to a bronze thru-hull with both water temperature and speed sensors.

For our on the water testing we mounted the display using the accompanying bracket and found that it held the display unit securely.

Ports on the case back connect to a power and transducer cable using twist-lock connectors. A single ground wire connection is on the back too. This fishfinder can interface with a Furuno GPS sensor as well as some other NMEA0183 capable devices.

Screen Size and Viewability

The Furuno LS6100 has a monochrome LCD screen measuring 4.7-inches high and 3.5-inches wide. On the diagonal the portrait layout screen is 6-inches across. Screen resolution is 320 pixels vertically and 240 pixels on the horizontal plane.

We viewed the screen in open sunlight and found it to be fairly bright and adequately sharp with good contrast when viewed from straight-on. I gave it a good rating for daytime viewability. When viewed at night I rated the screen excellent.

Obviously, because it is a monochrome screen it only has two color selections to choose from, white background is for daylight viewing while a black background is used for night viewing. Screen backlighting on the Furuno illuminates the entire screen evenly. It has ten levels of back light adjustment.

Controls and Operation

Pushbutton controls are on the right side of the front panel. The LS6100 has three menus, main, system, and installation. Each is reached with a press of the Menu/Esc key, then a selection is made with the cursor pad arrows, and finally the selection is accepted and executed with a press of the Enter key.

Gain control allows the user to switch between two automatic gain settings, fishing or cruising, and manual gain using front panel pushbuttons. The user can set the gain offset to adjust the automatic settings or switch to manual gain.

Functions and Features

Some notable features on the Furuno LS6100 are A-scope, bottom lock, shift, variable zoom, adjustable picture advance speed, and whiteline. Bottom lock, shift, and zoom effectively increase the screen resolution by showing only a portion of the water column on the screen.

Furuno LS6100 Specifications

Power (Watts RMS)300
Frequency (kHz)50 / 200
Transducer Used for TestAirmar P66
Auto Depth RangingYes
Manual Depth RangingYes – 8 steps
GainAuto(2) / Manual
Bottom LockYes
Warranty Period (Years)(2)Parts / (1)Labor

A-scope shows in real time what is directly under the transducer. As the transducer receives information and sends it to the display to write a new vertical line of pixels to the right side of the screen this information is also shown on the right side of the screen expanded horizontally. This horizontal expansion is what allows your eye to easily view this information.

Whiteline helps differentiate bottom types. With Whiteline activated the bottom will show as a thin black line under which varying depths of white will show indicating strong or weak echoes, this makes it easier to determine bottom hardness and differentiate between bottom and objects like fish sitting close to the bottom.

Zoom mode selection is accessed through the sounder menu and can be set to bottom lock, bottom zoom, or maker zoom. Bottom lock range can be set to between 10 and 30 feet while bottom zoom can be set to anywhere between 7 and 150 feet.

Picture advance can be set to one of eight speeds ranging from stopped to 4 times the ping rate. For our testing we used the 1/1 speed setting which writes one column of pixels for each ping of the sounder.

The display screen color palette can be set to white, blue, black, monochrome, or night. We used the default white for our daytime testing due to bright sunny test conditions.

The LS6100 will connect to an optional Furuno GPS sensor and can display up to 12 waypoints with a rudimentary navigation mode.


Performance testing was done in salt water using the transom mount transducer selected and supplied by the manufacturer. Testing was accomplished by making multiple passes over known bottom structures in various depths. Some of the evaluation was conducted over a large steel wreck in 120 feet of water. An additional deep-water review was carried out while drifting over a steel structure in 290 feet of water. The Furuno LS6100 performed well at all depths and earn good or excellent ratings overall.

Buy this Furuno fishfinder here.

Final Thoughts

The Furuno LS6100 has functions and features normally only found on much more expensive fish finders. Combine this with overall excellent performance and you’ve got a winner. Make sure when you order this unit you add a transducer appropriate for your boat and usage.