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Depth, Temperature & Speed

For those who love to troll for trout, salmon, steelhead and walleye, three words should be on your lips at every fishing adventure.


Finding fish is fundamental to fishing success, yet it amazes me how ill equipped many anglers are when it comes to using sonar effectively. Sonar technology has so rapidly evolved in recent years, that it’s surprisingly easy to find yourself using flip phone technology in a smart phone world!

If you are one of those “flip phone” guys, it’s time to dig in and educate yourself on the advancements of modern sonar. While traditional broad beam sonar is still the primary tool used to locate open water species, if your sonar is not equipped with something called “chirp” technology you are not seeing the full picture. Chirp sonar is a multi-signal version of broad beam that delivers much greater detail and more precise target separation than possible with traditional single channel broad beam sonar.

Modern large screen sonar units can be equipped with multiple sonar types including broad beam, chirp, down scan, side scan and 3D scanning capabilities.

With the help of chirp sonar it’s possible to mark fish feeding within dense balls of baitfish, to see fish inside weed cover and to clearly mark fish laying belly to bottom. Chirp technology also allows us to identify individual fish, regardless of how close they might be, so we can better judge how many fish are using a particular area.

With traditional broad bean sonar, these fish would blend right into the bait fish, cover or bottom signal and essentially become invisible to the angler. When chirp technology was first introduced it was only available on the high end sonar/GPS units. These days, you can get the benefits of chirp sonar even on the most affordable units.

Incorporating larger screen sonar/GPS units or multiple units also allows anglers to monitor more than one sonar technology at one time, plus put GPS navigation and even auto-pilot electric motor functions at your finger tips. Networking multiple units together means when you save a waypoint on one machine, it’s automatically saved to others in the network system.


Most trollers pay attention to the surface water temperature to give them a hint as to how active fish might be and what lures are going to deliver the most effective presentations. Open water trollers need to also be concerned with water temperature at depth.

The new Fish Hawk X2 is a portable temperature and trolling speed probe that doesn’t require investing in a downrigger. Ideal for the multi-species angler, a transducer communicates with the depth probe to provide critical water temperature and trolling speed at depth.

It’s widely known that trout, salmon and steelhead seek out waters that fall within their temperature preferences. These bands of “sweet water” are often found deep below the surface. A sub-surface water temperature probe is the only practical way to find these comfort zones.

Back in the day, sub-surface temperature probes were hard wired with a special downrigger cable that allowed data to be transferred. Today sub-surface data can be monitored much more efficiently by using transducer based technology.

The Fish Hawk X4 Plus Depth unit uses a probe deployed on a downrigger that communicates depth, speed and water temperature information via a transducer signal. The probe and transducer communicate and display the information on a LCD screen.

Recently Fish Hawk introduced a “portable” version of this same technology called the X2. The X2 uses the same probe proved bullet proof with the X4 units mounted to a weight and deployed on a short rod featuring a line counter reel. Clipped over the line, a small transducer deploys a few inches under the water surface and communicates with the probe to deliver critical information including trolling speed at depth and water temperature at depth.

A downrigger is not required to use the X2 making this tool ideal for the multi-species angler.


Every fisherman who trolls has a need for speed. More specifically, trollers need to know the exact speed the boat and trailing gear is moving. Trolling speed is one of the most important elements of open water trolling and also one of the easiest to monitor and adjust.

Trolling speed is best monitored using “speed over ground” information from a GPS unit. A combo sonar/GPS unit is the most practical way to monitor trolling speed.

Adjusting trolling speed is a different deal all together. Most open water trollers use a four stroke kicker motor for trolling chores. These small remote engines do a nice job of propelling boats at trolling speeds, but they are not without issue. The biggest problem is these small outboards use mechanical throttle controls that make it almost impossible to dial in precise trolling speeds.

After market digital throttle controls installed on a kicker motor are the answer for anglers serious about establishing and maintaining precise trolling speeds. Digital throttle controls are expensive, but they are capable of splitting hairs when it comes to trolling speeds.

A few remote outboards like the Evinrude 15HO feature a built-in throttle control that allows the engine RPM levels to be adjusted in 50 RPM increments by simply touching a throttle control switch mounted right on the handle of the kicker motor. Sweet.

Another option for controlling trolling speed are the growing list of GPS guided electric trolling motors on the market. Commonly used in combination with a kicker motor, the gasoline motor provides the primary forward thrust and the electric motor is deployed to fine tune trolling speed and provide wireless navigation chores.

Wireless GPS guided electric motors like the MotorGuide Xi5 are changing the way anglers troll in open water. Wireless motors not only provide critical speed control, they can be used to navigate to waypoints and duplicate productive trolling runs.

Wireless GPS guided electric motors like the MotorGuide Xi5 are changing the way anglers troll in open water. Wireless motors not only provide critical speed control, they can be used to navigate to waypoints and duplicate productive trolling runs.

The MotorGuide Xi5 and Xi3 wireless electric motors feature GPS technology and they can be controlled via a hand-held key fob, a wireless foot control or via a sonar page thanks to another technology called Gateway. Gateway allows the electric motor and sonar to communicate, giving the angler the benefit of adjusting the electric motor speed, direction of travel, setting a GPS course, duplicating a productive trolling route and much more with touch screen convenience.


Open water trollers need all the help in finding and staying on fish they can muster. Modern tools of the trade including high definition chirp sonar, GPS navigation, Gateway technology, NMEA 2000 networking, digital throttle controls and sub-surface speed and temperature probes are paving the way to more successful days on the water.

Mastering so many different technologies might seem like a daunting task, but all of the manufacturers who produce these products also have customer service departments designed to make the transition painless.

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