The best lessons are those gleaned from on-the-job training. When it comes to fishing, those lessons can be the most fun, though often the most frustrating.
The Scotty Seeker™ represents a new advancement in trolling technology, allowing anglers to monitor water conditions in real time.
One of those early lessons learned on my boat dealt with trolling speed. Some days I noticed most of the fish we caught and most of the bites we got came when I was trolling one direction. Were the fish all facing one way? Could they only see the lures approach when I was going north and not see them when I headed south? Very doubtful. Was I going faster when heading north and slower when heading south? “Possibly’” I thought at the time - but now I’m positive that was the case.
If it had been a day with brisk winds, blaming the one-way-success on the wind and trolling speed would have been an easy call, but what about nearly calm days? The waves were only about one foot and really, nothing indicated the wind was speeding me up or slowing me down enough to make a difference. I even bumped the throttle a bit on one pass to see if that helped. It didn’t. Maybe the fish were all facing one way. Maybe the angle of the sun on the lures made a difference. I don’t know, but the next time a similar thing happened, the conditions weren’t similar.
Instead of being nearly calm, I was fishing in one to three-foot waves. Our first half dozen strikes came on our downwind troll, nada when going upwind.
Again, the only thing that made sense was speed, but how to measure it? GPS wouldn’t be available for a decade or so. The only “affordable” device capable of measuring trolling speed was the Luhr Jensen Trolling Speed Indicator which operated on a simple pendulum system. A three or four-ounce weight was suspended from a bracket over the side of a boat. It would hang straight down when the boat was in neutral, but when the boat was moving, water pressure on weight caused the weight to trail back a bit and move an indicator showing an approximate trolling speed. A little more speed moved the indicator a bit more. It registered the speed from zero to five knots or zero to 5.8 MPH. I have no idea how accurate it was but in practice it really didn’t matter (at least for fishing.)
What did matter is if I was catching fish while the needle was registering two knots, chances are if the wind comes up and speeds up or slows the troll, adjusting the trolling speed to two knots would usually keep me in the game.
The big picture lesson was that in my relatively small, aluminum boat, the wind affected my trolling speed significantly more than I expected and I had to adjust the throttle much more to keep my boat going at fish-catching speed than I’d ever imagined. An extra 300 or 400 RPMs might work in on gentle days while an increase or decrease of 800 or a thousand RPMs might be needed on windy days. The important thing was, never again did I have the problem of only being able to catch fish while trolling one particular direction – at least on lures trolled near the surface.
Despite wind and whitecaps on the surface, a speed and temperature at depth probe was key to putting the lure that tempted this salmon in the right place at the right speed.
New Boat, New Toy
I retired my Luhr Jensen speed indicator when I got a new boat and installed a Moor Electronics “Osprey” trolling speedometer on it. Instead of a pendulum, the Osprey had a paddle wheel that mounted on the stern. The paddle wheel spun faster or slower as the trolling speed changed and the dash-mounted readout showed the speed.
Actually, it showed the “average” speed, which was better. As a boat trolls, even in moderate waves, it’s constantly speeding up and slowing down. The smaller the boat, the more this varies. The Osprey, however, averaged the high/low/medium spins of the paddle wheel and showed that average on the dial. I didn’t appreciate that until electronics’ manufacturers started putting paddlewheel speedometers on the transducers of their sonars or GPS speed reading on their screens. In three-foot waves on my boats surface speeds often surged from the one-point somethings to way over three MPH.
The Osprey nearly eliminated my one-way catching issues for lures fished near the surface or high in the water column. However, the problem persisted some days in deep water when sending my lures 50 feet, 70 feet or deeper in late spring and in the summer.
I suspected it had to do with currents affecting my lures’ trolling speeds, but gauging those speeds with only a surface speedometer is tough. I needed a subsurface speedometer.
Currents High and Low
Depending on where you are fishing, the frequency of having lure-speed altering currents may vary from “ usually or some of the time” to “hardly ever.” The Indiana portion of Lake Michigan, where I fish most often, is a “some of the time” area. I soon learned that when I’m fishing “the rest of the time” I needed to know what was happening deep below the surface to keep my lures in the right place and the right speed.
Speed and temp probes help ensure memories are made on every trip.
There are clues a captain can key in on at the surface, but they are crude estimates, at best. Watching the angle of the downrigger cables between the arm of the ‘rigger and the water surface can be a clue. If the GPS or other speedometer measuring speed at the surface shows the same speed going both north and south (or east/west) but the angle of the downrigger cables go from almost straight down to 20 degrees, 30 or even 45 degrees when going the opposite direction, there’s some current flowing that will be messing with the lure speed way below as the boat trolls with or against the current flow. Another indication of current is if your downrigger cables are deflecting to the port or starboard. This time it’s a cross current.
The location of the current can vary, as well. A strong or prolonged wind can produce surface currents where the upper part of the water column is moving near the surface while the deeper water is not moving, perhaps moving slower or it could be moving in a different direction than the surface layer. At other times, the surface water isn’t moving very fast, but there’s a subsurface current. The downrigger cables and other clues can make you suspect that there’s a current, but it won’t tell you how it’s affecting your lure speed.
Temperatures High and Low
The water in most lakes (Great Lakes or otherwise) isn’t ever the same temperature top to bottom, side to side. Since warm water floats on cold water (most of the time), the temperature at the surface is the warmest, the temperature in the depths is colder and all a fish needs to do to find comfortable temperatures is to move deeper or shallower. Most of the time.
In the Great Lakes, wind can and does move the water around. Often the wind driven surface waters pile up on the downwind side of the lake and when it does, often the cool, subsurface waters are pulled closer to the surface on the upwind side.
The important thing is knowing salmon, trout, walleyes and other fish all have a preferred temperature range and most of the time they instinctively move higher or lower in the water column to find their comfort zone, though sometimes they can move inshore or offshore to find their happy place.
All a fisherman has to do is drop a thermometer into the depths and take the water’s temperature at a variety of depths to figure out what’s happening. I used to have a thermometer made by Fish Hawk Electronics that did just that. It came with 100 feet of cable on a spool and on the side of the spool was a dial that showed the temperature at the end of the cable. With the boat in neutral, I’d hook the sensor to a downrigger weight and send it down.
Fish Hawk’s X4 is unique in that it displays both surface and depth temperature on the same screen.
In the summer I’d watch the temperature drop from the from 70s at the top into the 60s twenty feet under the waves and continue to decrease with depth. At some level, however, the temperature would drop from the mid-50s to the mid to upper 40s in about 10 feet. This is the thermocline level that separates the cold bottom waters from the sun-warmed surface waters.
The thermocline is important because walleyes often seek out the waters just above the thermocline, lake trout almost always hover somewhere under the thermocline while salmon and steelhead hang out just above, below or in the transition layer. My thermometer on a cable showed those zones perfectly – but only at the spot I ran the test.
Because of the thick cable I had to remove the thermometer from the downrigger weight before I started trolling. Most of the time that wasn’t much of a problem since the level of thermocline is usually fairly stable -usually, not always. Move a hundred yards the initial readings are probably good enough. Move a couple miles and the thermocline might be higher or lower.
Probing The Depths
Moor Electronics was the first company I heard of that sold a thermometer that could be hooked to a downrigger weight and send a signal up to the boat that showed the water temperature at the level the weight had been lowered. Called a SubTroll, the thermometer was incased in a cylindrical tube, called a probe, about the size of a flashlight with three D-size batteries inside. I don’t know what size batteries were actually required; most of the interior was filled with the circuitry that measured the temperature and more.
The more was a speed-measuring paddlewheel on the outside of the probe that rotated as the unit was pulled through the water and measured the trolling speed of the probe, the downrigger weight and the lure trailing behind. SubTroll users discovered (as I suspected) the speed measured at the surface was often different than the speed at the ball. At times the surface speed and the down-under speed difference could be well over 2 mph different.
If a boat is going 2.4 at the surface, but the lure below is in a current going 2.2 mph the same direction as the boat, the lure’s is only trolling at .2 mph and probably not going to have an appealing action to the fish. Turn the boat 180 degrees, keep the top speed at 2.4 and the lure is now trolling at 4.6 mph. Most lures spin out of control at those speeds or at least lose their fish appeal.
The SubTroll was a game changer, but the issue was with the size of the probe and because the speed and temperature readings were transmitted to the top through a special, nylon coated downrigger cable. Not only was the probe fairly large, the special downrigger cable was larger in diameter than regular cable and the extra drag of the probe and cable almost doubled the amount of deflection (blowback) on the cable and downrigger weight travelling through the depths. The meter on the downrigger could show 100 feet of cable deployed, but due to blowback, the actual depth could only be 70 or 80 feet, depending on trolling speed.
Using the Scotty HP downrigger in conjunction with the Scotty Seeker system is the precise way to place your gear at the exact depth salmon are traveling at.
A heavier downrigger weight helped, but going from a 10 pound to a 12 pound, even to a 15 pound weight didn’t solve the blowback problem. Still, the increased success experienced by anglers equipped with a SubTroll made coping with the blowback worthwhile for many. A few guys are still using their old SubTroll units but Moor electronics is now out of business and new units are no longer available.
It wasn’t long before other manufacturers developed their own version of the speed and temperature probe. One of the most popular, these days, is the Fish Hawk X4, made by the same company that made my temperature probe which they no longer make.
Unlike the SubTroll, the probe on the X4 is about half as bulky. That helped with the blow-back problem to a degree. However, the speed and temperature data is sent up to the boat wirelessly from the probe to a receiver mounted like a sonar transducer to the stern of the boat.
That further negated the blowback caused by the larger diameter downrigger cable required on the SubTroll.
The transom mounted signal receiver allowed a new feature to be included with the X4. A paddlewheel speed measuring devise is integrated into the receiver on the transom so both the speed and temperature at the surface and the speed and temp at depth is registered on the display. Many anglers find this a better and easier-to-read indicator of boat speed than watching their GPS reading.
Fish Hawks’ speed and temp probes are still available, but the rechargeable lithium-powered probe reduces blowback significantly.
Last year, Fish Hawk created a new, rechargeable probe, about half the size of their battery powered probes. The size further reduced the amount of blowback and solved the problem of constantly having to swap out the disposable batteries. Pop the probe on a charging dock plugged into a USB port at the end of the day and it’s ready for tomorrow – and probably the next.
There is a strong contingent of anglers who use Fish Hawk’s main competitor’s unit, called the Depth Raider - produced by Kell Outdoors (www. kelloutdoors.com). Though the temp and speed signals are transmitted up the downrigger cable, (plastic coated – thus slightly larger in diameter), the probe is quite compact. I’ve never noticed any more blowback using the Depth Raider than the Fish Hawk’s original battery powered probe. The Depth Raider only registers the speed and temperature at the depth of the downrigger weight, not at the surface.
There’s a newcomer just entering the speed and temp at depth market called Seeker. It’s being sold by Scotty Fishing, maker of Scotty downriggers, rod holders and many other quality products www.scotty.com. The Seeker, like the Fish Hawk units transmit the signals wirelessly to a hydrophone receiver mounted on the boat’s transom.
The Seeker System will display speed, water temperature and lure speed on most multi-function chart plotters. And can also display on a cell phone screen via bluetooth.
The probe itself is sleeker and more hydrodynamic than other probes. It is powered by a lithium battery and recharges when placed on a charging dock connected to a USB port.
Unlike all the other probes, it does not come with a stand-alone display module to show the information being beamed up from the depths. Instead, either hook it up to a Lowrance, Garmin, Raymarine or other multi-function display sonar or chartplotter and the info will show on these screens along with the usual data. Another option is to use a cell phone (Apple or Android) as the display. The phone will pair to the Seeker’s hub via Bluetooth.
Like the Depth Raider, the Seeker doesn’t show the speed at the surface, but there’s an amazing fix available. The Seeker can be used with up to four probes simultaneously. Simply attach a second (or third or fourth) probes to additional downriggers and the hydrophone will identify them and display each one’s info on the MFD screen or phone. Buy a spare probe and run one lure high in the water column to gauge the trolling speed up top.
The Seeker’s probe sits on a charging dock to recharge when not in use.
Another feature I like is that the Seeker measures the actual depth it’s running. Few downrigger counters are spot-on and when considering the blowback all downriggers experience, the reading on the downrigger counter isn’t precise. A water-pressure sensor in the Seeker probe shows the exact depth it’s deployed. This can be a great assist when setting diving planers, lead core, copper or other weighted lines. A review of the Seeker unit I used on a recent trip to Lake Erie is in this issue’s Tackle and Toys Column.
A post on a popular Great Lakes fishing site nailed it. “With bite time limited, having the right information about temperature and speed the moment your presentation hits the water saves all that trial and error time. We are looking for that 48 - 53 degree water in the summer and as we troll several miles that band of water can shift, currents change to affect your speed at the lure. With a speed and temperature probe I can make changes right away.”
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