Features May 15, 2005 Issue

Trolling Motor Test

Minn Kota's 3X steering and ergonomic features push the RT80/S-3X past the competition in the 80-lb. thrust class. In the 50-lb. class, we like the no-frills MotorGuide SW46 HT.

The Minn Kota RT 50 goes through its paces during our speed testing.

After we published a short article last year (PS Nov. 15, '05 "Alternative Auxiliary Power") detailing our experiments with an electrical trolling motor, we were surprised by the number of readers who responded via letters and e-mails. It seems a significant number of boat owners appreciate that these quiet, efficient devices are almost ideal for propelling small to mid-size dinghies. What was really surprising was the number of people who wrote to tell us that they use an electrical trolling motor as the main source of auxiliary propulsion aboard sailboats, inluding one 30 feet LOA.

In the aforementioned article, we wrote that we'd report on the service and longevity of the 55-lb. thrust Minn-Kota we purchased. That report will come later. In the meantime, we decided that there was sufficient reader interest to justify a test of trolling motors. Whether you plan to use one on a dinghy, a canoe, or to push the mothership along, you'll want to know if it can perform as advertised. So we gathered up four representative models to determine the facts on each.

What We Tested
Models from two manufacturers dominant in the marine electric trolling motor marketplace—Minn Kota and MotorGuide—comprised our test specimens. From MotorGuide we obtained two motors from its Great White Saltwater Series: a 24-volt SW82 HT and a 12-volt SW46 HT. To compete against this pair, we also obtained two Minn Kota Riptide Saltwater trolling motors, a 24-volt RT80/S-3X and a 12-volt RT50/SC/S. These four motors fit nicely into two groups for testing. The pair of 24-volt, 80-lb.-thrust motors in the $550 to $600 price range formed one group, while the two 12-volt, near-50-lb.-thrust motors, both priced at $300, formed the other.

How We Tested
All four trolling motors were tested on a 16-foot skiff. To mount each product, we installed a removable bracket that screws to an aluminum plate permanently secured to the bow of the skiff. Typically, sailors mount these engines on the transom (or perhaps on the crossbeams aboard a multihull), but our test platform was chosen because its length and weight (including the permanently mounted gas-powered outboard) approximate the average size vessel represented in the responses we had from readers.

This setup meant that we had to swap things around a bit. To keep each unit in the optimal position, facing astern, we needed to turn the control heads on all the motors 180 degrees so the controls would be facing the operator. A more detailed description of how easy this was to accomplish is contained in each motor's review.

Out of a cadre of four high-quality, 12-V group 27 marine batteries, we selected a single battery for use during each 12-volt motor test and a pair wired in series for each 24-volt motor. Prior to each test, batteries were recharged and checked to assure they were in a fully charged state.

We began each series of tests by mounting the motor and then running the boat down a section of a saltwater canal at maximum thrust. A single tester was aboard for the initial speed and amp-draw testing. The canal had no current flow, but there was a light breeze blowing parallel to it. To negate the effect of the wind, we averaged the speeds obtained on an upwind and downwind run. Amp draw was recorded on the downwind leg and each motor was connected to the power supply without a circuit breaker.

The following day after recharging our battery bank, and with the assistance of a second tester, we conducted static thrust testing. Each motor was remounted and hooked up to the appropriate battery power. One tester operated the motor and the other took measurements.

For the smaller motors, we used a single 0 to 50-lb. hand scale held fast to a dock with a stout, pre-stretched line. The larger motors required the use of a pair of hand scales. Both scales were identical. Readings were added to obtain a total thrust rating. To garner accurate readings on the hand scales, each motor was slowly brought up to maximum thrust and positioned to minimize any side-to-side boat movement. Each motor was set in the water as deeply as possible for this test; we were very careful not to record readings if any propeller ventilation was evident.

Following the completion of measured testing, each motor was run at various speeds in our canal to further review handling and operational qualities. We also assigned ratings for the quality and security of each trolling motor's transom mounting bracket.

Minn Kota RT80/S-3X
The Minn Kota RT80 is a 24-volt electric trolling motor rated at 80 lbs. of the thrust. The RT80 can be adjusted vertically, as needed with the depth collar, and tilted and locked, between vertical and horizontal, in 9 positions using the tilt-release button. It's tiller handle extends out 27" minimum from the motor shaft and can extend to 32", which is a plus for those sailors who would use this in a dinghy where the seat is set well forward of the transom. Also, the control head pivots upward in three steps to a maximum of 20 degrees. A sacrificial zinc is an integral part of the propeller nut.

Twisting the tiller handle turns the motor on/off and regulates the propeller speed much like the volume control knob on a stereo; there are no preset speed levels. A large arrow on top of the control head indicates the direction the motor is pointing much like a rudder indicator on a large vessel. We found the long tilting tiller handle made this trolling motor a dream to operate, though when the motor is tilted for on-deck storage the long handle takes up a lot of space. If space is really tight, the handle can be removed fairly easily by pressing a push button and pulling the handle off.

One major operational enhancement on the RT80/S-3X—not found on any of the other trolling motors we tested—is the 3X steering. By its very nature this feature makes this motor unique compared to the others tested. Essentially what happens with the 3X steering is that when the operator moves the tiller handle to redirect the thrust of the motor, the handle need only be moved one-third of the desired amount. For example, if you wish to change the direction of the thrust from straight astern to directly to port, a 90-degree direction change, the tiller handle need only be moved 30 degrees. In actual operation this makes the job of steering very easy as only small movements are needed even for large course changes. It also negates the need for reverse since moving the handle about 60 degrees to the side actually turns the motor/propeller unit 180 degrees. An integral part of the 3X steering system is the tube-within-a-tube construction method. The inner composite tube actually used to steer the motor unit is contained inside an aluminum outer tube. This combination adds significant strength to the complete assembly. The 3X steering does take a little getting used to, but it’s very convenient after that.

To operate this motor on a bow mount, as we did for testing, does not require turning the control head around like on all the other trolling motors. Instead the RT80 has a backtroll feature, actually a mechanical adjustment that allows the control head to be spun around simply with the flip of a lever. This was a feature we appreciated. The process of reversing the control head, which took several minutes on the other motors, took about a second on this one.

The RT80 did well in our performance testing, too, even though it lacks the brute horsepower of MotorGuide's 80-lb. thrust motor. At maximum thrust, the RT80 managed to push our test boat along at a respectable 3.6 mph while drawing about 45.5 amps. In our static thrust test, it produced 59 pounds of thrust. Overall we found the RT80 had more than enough power to move our test boat around easily and we really liked the way it handled with the 3X steering.

The transom-mount version of the RT80 is equipped with a beefy metal bracket with clamp screws similar to what one would find on a small gasoline outboard. This mounting system performed exceptionally well during testing and received an Excellent rating. We noted very little vibration or mount movement even during turns at high power settings.

The Minn Kota RT80/S-3X weighs in at 34.5 pounds, is available in the both a 42" or 52" shaft length, and carries a three-year warranty.

Bottom Line: Though this is the most expensive unit tested, the Minn Kota RT80/S-3X has a long list of features we like. They include its long, removable tiller handle, upward tilting control head, battery monitor, direction indicator, and the real standout—3X steering. All these features make this trolling motor our top pick.

MotorGuide SW82 HTV
MotorGuide of Tulsa, OK, rates the 24-volt SW82 HTV at 82 pounds of thrust. A plastic collar that rides on the stainless steel main shaft is used to set motor depth; the collar is locked in place with a setscrew. The motor can be locked down, tilted completely out of the water, or set in one of five additional intermediate positions with the tilt-position pin. A steering tension adjustment screw is located at the base of the mounting bracket. When tilting the motor out of the water for quick storage, a lever located on the rear of the mount can be used to lock the shaft in position; it’s called the "quick stow lever."

The tiller handle extends 15" from the main shaft and can be easily extended to 21". The control head does not tilt upward. A sacrificial zinc is clamped to the main shaft near the motor-prop assembly.

Located on the bottom side of the control head is an off-on switch that cuts off all power to save your batteries should you inadvertently leave the tiller in an on position. Setting the tiller to a center position turns the motor off. Turning it clockwise, you can select various forward speeds, and counterclockwise for the reverse speeds. Motor speed in either forward or reverse is infinitely variable; there are no preset speed levels.

We had to spin the control head on this motor to properly operate it on the bow of our test boat. This requires removing six screws that secure the control head top, the removal of an internal tiller shaft bracket held in place with two screws, the removal of a support plate again held in place with two screws, and finally the removal of the bolt securing the control head to the main shaft. Once all this is accomplished the head can be spun 180 degrees and everything put back together.

MotorGuide even has an instruction sheet on how to do this procedure and will send it to owners. We did not wait to receive the instructions before attempting the change and found it fairly easy to accomplish in about fifteen minutes with the proper tools.

The SW82 outperformed all comers in speed and static thrust testing. It pushed our test boat along at 4 mph and managed to produce 66 pounds of static thrust. Amp draw at maximum thrust was 55.5 amps. The motor had more than enough power to maneuver our skiff and provides plenty of spare horsepower to battle strong winds or currents.

Its transom mount is hefty, though not as stout as the Minn Kota bracket, and uses large diameter rubber grips on the clamp screws to facilitate tightening. We found the mount on the SW82 to be a bit lightweight for this powerful motor. At high power settings we noticed some mount movement and strain. We gave the motor mount a Fair rating.

MotorGuide's SW82 HTV weighs 28.5 pounds and is only available with the 45" shaft length. It carries a three-year warranty.

Bottom Line: A very powerful trolling motor. Though it's lighter than the Minn Kota RT80/S-3X, it lacks most of that unit's ergonomic advantages.

Minn-Kota RT50/SC/S
As the model designation implies, the 12-volt RT50 carries a thrust rating of 50 lbs.A plastic collar riding on the composite main shaft, locked in place with a setscrew, sets the propeller depth. Like its big brother, the RT50 can be locked in any of 9 positions between vertical and horizontal. Steering tension is adjusted with a setscrew on the mounting bracket. The pivoting tiller handle length is fixed at 14" from the main shaft. It pivots up in three positions to 45 degrees and when unlocked can pivot down 45 degrees as well. A sacrificial zinc anode is part of the prop nut.

Twisting the tiller handle clockwise out of the center position turns the motor on and allows setting one of five forward speeds. Going counterclockwise sets one of three reverse speeds.

To operate properly on our test boat, we needed to spin the control head on this motor in the opposite direction. Removing one bolt, spinning the head, and replacing the bolt is all it takes. The job was very simple and took only a minute to accomplish.

The RT50 demonstrated more than adequate power on our test boat in moderate wind. In speed testing, it pushed our skiff 2.9 mph at maximum thrust while drawing 51 amps. During static thrust testing, it managed a respectable 34 lbs. of thrust.

The plastic mounting bracket used to secure the unit to a transom was adequate at lower power settings, but when we shifted to full power it showed signs of being under stress, especially when making turns. Movement was noticeable, and this forced us to give the mount just a Fair rating.

The Minn Kota RT50/SC/S weighs 21 pounds, is only available in the 42" shaft length that we tested, and carries a three-year warranty.

Bottom Line: By a hair, the RT 50 is the top performer in its class. We like the tilting tiller handle but not the plastic transom mount.

MotorGuide SW46 HT
The MotorGuide SW46 HT is a 12-volt motor rated at 46 pounds of thrust. It has many of the exact same features as its big brother, including a locking depth collar, seven lockable tilt positions, a steering tension screw, no control head tilt, a zinc clamped on the main shaft, and a "quick stow lever." The tiller handle measures 14" from the main shaft and does not tilt or extend.

Like the other units, speed control is accomplished by twisting the tiller handle. The SW46 has five forward speeds and two reverse settings. The center position switches the motor off.

For proper operation on our test boat, the SW46 required spinning the control head 180 degrees; the procedure required to accomplish this is identical to that of the SW82.

We found the performance on the SW46 more than adequate to maneuver our test boat and would expect no problems in moderate wind or current. The numbers it posted were nearly identical to the Minn Kota RT 50. In speed testing, it went 2.8 mph while drawing 49 amps, and managed 32 pounds of static thrust.

The transom mount bracket on the SW46 is exactly the same mount as is used on the much larger and more powerful SW82. It has all the features of the SW82 mount, but at this lower power rating proved more than sturdy enough and received a Good rating. We noticed little vibration or movement even while making turns at full power.

MotorGuide's SW46 HT weighs 22 pounds, is only available in the 36" shaft length that we tested, and carries a three-year warranty.

Bottom Line: A no-frills trolling motor with good performance and a robust mount; just make sure that the 36" shaft length is right for your boat.

Conclusions
When selecting a trolling motor for your boat, no matter the style of mount you choose, it's important to get the correct shaft length. Follow the manufacturer's recommendations and make sure that when properly installed on your boat, the trolling motor propeller can be set well below the water's surface. Minn Kota recommends that the top of the motor housing be at least 12" under water to alleviate any problems with propeller ventilation.

Even though the Minn Kota RT80/S-3X was slightly outperformed by the MotorGuide SW82 HT and is about $40 more expensive, we think it handily beats the competition with a long list of exclusive features, which figured prominently in our ratings and choices. We liked the long, adjustable tiller handle, tilting control head, built-in battery monitor, backtroll feature, and 3X steering. These features make the product easier to use and more versatile, which is important given the wide variety of dinghies and sailboats aboard which it might be used.

In the 50-lb. thrust class, we picked the MotorGuide SW46 HT over the Minn Kota RT50/SC/S. Priced the same, these smaller units fared almost identically in our tests, but the transom mount on the SW46 was stout and secure while the RT50's was plastic and pliable.

 

Also With This Article
"Value Guide: Trolling Motors"

Contacts
• Minn Kota, 800/227-6433, www.minnkotamotors.com
• MotorGuide, 920-929-5040, www.motorguide.com

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