The Offshore Voyaging Reference Site

EchoPilot Forward Scan Sonar FLSII

We have found that having a forward scan sonar has made exploring in the high latitudes safer and more feasible. Instead of feeling our way along at 2 knots when off the charts, we can now travel confidently at 6 knots, since the forward scan reaches out up to 200 meters ahead. Also, the sounder makes it possible to feel our way into tight anchorages, even when the water is not clear enough to see the bottom.

This is first generation technology: the interface is clunky and non-intuitive; the buttons are difficult to use especially with cold hands; and it takes practice to interpret the readout. There are several other issues that are important to know: the transducer is vulnerable to damage from ice, so we carry a spare; and the sensitivity is variable between units. We went through 2 units and 2 transducers before we got a combination that reached specification. However, the British manufacturer and the Pilot Marine, the American distributor, have been very responsive to our problems and their newer models fix many of our complaints about the FLSII, albeit with a shorter range.

The EchoPilot has made a huge difference to our ability to cruise safely in the high latitudes. It isn’t necessary, however, to go to the high latitudes to get good use from a forward scan sonar: We use it all the time, even in well-charted waters, to guard against the consequences of a navigation mistake and when anchoring it allows us to survey for anchor placement with much greater accuracy and less hesitancy about getting too close to shore.

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Nick Kats

This is brilliant, looking ahead 200′.

Here is an unrelated Q on depth sounders/fish finders.

Mine is good to 600′ deep.

Seems for cruising the ideal would be 5000 ft or so.

Cruisers have more needs than the coastal sailor who sails in shoal waters only.

A mile-deep sounder would ID continental shelf edges, sea mounts etc. It is useful as an additional tool for location on the charts and, in bad weather, staying in deep waters.



We have been using Echopilot’s FLS GOLD for 10 years now. In that time we have had one transducer failure. We have been cruising in tropical waters (mostly), but even in the tropics you cannot always see the bottom in 4m (12′) of water. The echo sounder is fantastic. The distance ahead depends on the depth, and whilst finding your way around in the shallows, off charted areas, we still proceed at a cautionary speed of 3 to 4 knots. For cruising you really need to see the bottom from about 40m (120 – 150 feet). The FLS Gold will read down to 100m in perfect conditions and from 30m in poor conditions (soft mud).
We used a combination of radar, GPS/Maxsea, and the echo sounder to enter into Cocos Keeling atoll by night. We thoroughly recommend this piece of kit. A point to beware of: The beam width of the transducer is only 2 or 3 degrees; if you are making leeway a rock can come at you from outside of the beam path!


Hi John, Yes we too find that the back light control is far too coarse, with settings that are mostly too bright. It would be better if the brightness control was logarithmic rather than linear. Also the shallow/depth alarm cannot be used! We get surface clutter from the wind & sea whilst traveling, and see the anchor chain sometimes at anchor. Regarding the beam width, it sounds like the Platinum is a much wider beam than the Gold pro combination.

White Princess

Nick Kats

John & Mike
Thanks, great info.
Is this the only active sounder on your boat?


Hi Nick, Yes this is the only sounder. Our backup is a lead line!

Mike Dorsett

“Old Ones Are BEST”
On s/y White Princess, we have had an FLS GOLD for the past 11 years, with it we have sailed 55,000 miles and made late night entries into strange places. The forward looking sonar is a definite advantage particularly where the charting data is not precise.
However the LCD display has succumbed to the effects of sunlight, and is now unusable. We replaced it with an FLS 2D and were very dissapointed!!! Echopilot have now housed the unit in a cheap plastic case that is not waterproof. The buttons are particularly nasty to operate. If there was no key bleep function (which I personally hate) you would not be able to tell if when a button had been pressed. Also the colour display is fronted by a very highly reflective screen, and you need to turn the brightness up to full in order to read it in tropical sunlight. ( with the sunlight on you all you see is your own reflection in the screen. Also the menu text is too small to read without glasses. I am 53 years old, and my sight has deteriorated a little. The 6 point characters are too small to be safe. Additionally Echopilot have removed the Log facility and the NMEA in/out facility. The FLS gold, having this facility could output the Depth below keel to another instrument so it can be used even if the display fails. We also couple the nmea depth output into MaxSea, our navigational & Charting software. This enables us to record depth data in poorly charted or un-charted areas.The log processing was useful but not essential. As a result of these ‘improvements’ the new range of products from Echopilot can now be classified as ‘Flash toys’ rather than a useful instrument. We would not now recommend this product to a blue water cruiser as a primary source of depth information. This means that you will also need a primary sonar operating on a frequency other than 200kHz.
I would also note that our new FLS 2D has gone faulty in less than 1 year, requiring an expensive return to manufacturer.

WANTED: now to the main point of this post: If any one out there has an FLS GOLD or SILVER display unit as a spare or other wise working display (not burnt) Even if the rest of the unit has a fault, I would be interested in acquiring one or two units to fix my existing FLS GOLD.

Mike Dorsett
s/y White Princess

peter nicholls

Dear Mike, Glad to know the boat we supplied you and which you fitted out has traveled so far. Best wishes Peter Nicholls

William Koppe

Hi John,

Fitting an echopilot platinum and note there is no plug for when the unit is not needed.
Logs and depth sounders always have them to stop growth in the skin fitting.
Do you keep the transducer always mounted, antifoul the fitting or use some other method?

William Koppe

Thanks John,
Echopilot have advised that they don`t have plugs and they are not needed.
I think the best bet, is to obtain a broken transducer, and cut off the protruding part, which is sacrificial, and use that as a plug.