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Electric essentials – choosing and using the right electric motor
  |  First Published: December 2004



For dedicated lure anglers fishing estuaries, rivers and impoundments, electric motors have become almost as necessary as boats, lures, rods and reels.

From lightweight transom-mount models for canoes or punts all the way up to the 24-volt beasts that dominate the bows of tournament boats, electrics have taken this form of fishing by storm. Their near-silent thrust gives anglers new stealth when hunting wary fish. Their instant power at the touch of a switch means more time fishing and less time fiddling with outboards or paddles to control the vessel’s orientation to the lures’ targets.

Trollers and drifters can now factor in a crosswind or headwind so their electric motor can keep the boat on course. In the birthplace of electrics, the US, auto-steer motors interfaced with sonar units can even work along selected depth contours, while GPS-interfaced steering is also incorporated.

There is now an electric motor for almost any application, for any boat under 6m and for any water you’d like to fish.

HOW THEY WORK

Power output is measured in pounds of thrust, thanks to the US origins, and the kilogram conversion just hasn’t made it here. Output ranges from around 24lb to more than 100lb, depending on models and makes.

Whatever the power, all electric fishing motors are fundamentally just a polymer or steel shaft with a sealed electric motor and a propeller on the bottom.

Unlike an outboard, which uses an engine above the water linked by a drive shaft to a gearbox and a prop, the ‘engine room’ of an electric is below water level. The little cowl on top houses only a few wires, switches or rheostats and, in the case of foot-controlled models, some steering gear.

Speed control is obtained by switching varying numbers of resistor coils in or out of the motor supply circuit. At full speed, no coils are switched into the motor circuit and full battery power is available. For slower speeds, more coils are switched in, dividing the battery power between the coils and the motor. The same amount of battery power is being used regardless of the speed setting. At slower speeds, the energy is diverted to the coils which convert it to heat is dissipated by the surrounding water.

In more sophisticated models a pulse-width modulation circuit ‘slices’ the battery’s direct current into short pulses varied by the speed control. As the speed is reduced, the battery is effectively switched off for longer periods.

Electrics range from simple tiller-steers, which are basically electric outboards, to cable-steered or servo-steered bow-mounts. Each has its merits.

TILLER MODELS

Tiller-steered motors are the most simple and inexpensive, although high-power saltwater models can still be over $1000. They just clamp onto a clear space on the transom of a dinghy or stub-tailed canoe and go about their business in the same manner as an outboard, with the usual tilt feature and the shaft retracting inboard. You can even rig up a side bracket for a larger canoe and clamp one there if lateral stability isn’t a problem.

Almost all tiller-steered electrics can also be mounted at the bow of punts and dinghies to give added manoeuvrability. For most tiller models, it’s just a matter of loosening a couple of screws or bolts and rotating the head of the motor 180° so the tiller faces inboard again.

Essentially, the turning fulcrum for a boat – the point around which a hull pivots laterally – is not far from where the bow enters the water, so it makes sense to have your steering propulsion close to this fulcrum and ‘pulling’, rather than at the longer end and ‘pushing’. It makes sense to mount an electric at the bow to exploit this efficiency.

Another efficiency issue is reverse gear. While almost all tiller-steered electrics incorporate one or more reverse speeds, most marine propellers operating in reverse are only about one-third as efficient as when they produce forward thrust. For maximum thrust when operating astern, pivot the motor 180° to gain full efficiency, although it might take a bit of a contortion to operate the tiller hanging out over the boat!

If most of your lurefishing is trolling, a tiller-steered electric on the transom is probably about as far as you need to go. The motor is right by the skipper and the controls fall close to hand – ‘hand’ being the operative word. You need one hand for the boat and the other for fishing.

FOOT CONTROLS

Electrics have been around in this country for more than 30 years but only in the past five years have foot-controlled motors experienced massive sales growth. Anyone who has extensively used a foot-controlled motor – especially if they spend most of their time casting – will never go back to a tiller. Period.

Foot-controlled motors, which adjust direction and speed with a pedal, simply maximise fishing time for the skipper. Regardless of pedal type, any competent boater should be able to master manoeuvring a foot-controlled electric within an hour or two.

With the rare exception of some very unorthodox mounting, foot-controlled electrics are bow-mounted, providing responsive steering and prime manoeuvring position from the forward casting platform. Foot-controlled motors don’t use reverse gearing, relying instead on pivoting the shaft and prop in the direction required – much more efficient.

Here’s where pedal-steered motors break into two families, cable-steer and servo-control.

SERVO-STEER

Servo-controlled steering relies on an electric motor, separate to the one that drives the prop, to rotate the shaft and direct the propeller. A rocker switch on the foot pedal activates shaft rotation left or right. The servo motor is incorporated into the deck mount of the motor and does its job from there.

Both major brands of US electrics available in Australia, Minn Kota (distributed by BLA) and MotorGuide, (from Mercury Marine), have servo-steered models.

There are many advantages to servo-steering, with no bulky foot pedal or inflexible cables, graduated steering and ease of use high on the list. Long power cords enable servo-steered electrics to be operated from virtually anywhere in the boat and you can even get radio-control units which will cordlessly operate all functions apart from stowing and deploying.

Propeller speed is usually determined by a slider or dial control on the pedal. Another switch controls power application, usually ‘momentary’ (available as long as the switch is depressed), ‘on constantly’, or ‘off’.

A servo steering motor also enables the addition of an autopilot feature that can steer the boat in a set direction. Autopilot electrics are fantastic for keeping a boat on a course into a headwind, or along a bank or weedbed. Simply set the motor on course and activate the autopilot and the servo goes to work with a series of small course adjustments whenever necessary. That’s great for trolling or search-casting – once the speed and course are set, you hardly have to think about the electric at all.

There are a few drawbacks. The servo motor does drain some extra power which the prop motor could otherwise use. The pedal servo switch is just another thing which can go wrong and poor maintenance or prolonged exposure to extreme conditions can lead to switch failure.

The ‘keying’ from the shaft to the servo motor also means that a servo-steer is usually raised and lowered around the keyway on the servo housing, which may be cumbersome for some people.

While the latest generations of servo-steer motors have increased steering responsiveness, the lag between touching the direction switch and the prop finally rotating around to the right direction can be a bit slow when instant steering is required in tight situations.

If the majority of your fishing is weaving in and out of snags, moorings, boulders and oyster leases, cable-steer might be more to your liking.

CABLE-STEER

Cable-steer electrics have been around a lot longer than servo models, with some primitive versions available in the US before 1960. They rely on a ‘cable within a cable’ to provide the mechanical steering effort in a similar fashion to an outboard motor’s remote steering cable or a clutch or accelerator cable.

By rocking the foot pedal forward or backward, the operator rotates the electric’s shaft left or right in an instant. The central pivot transfers the fore-aft motion on the inner cable through the outer cable sleeve (bundled up in a sturdy rubber sheath with the electrical cables) to the head of the motor, where a toothed rack rotates a cogged pinion at the top of the steering shaft. Around it goes, usually in about a 400° rotation from full heel depression to full toe.

Switching and speed control are similar to a servo motor’s.

The instant manoeuvrability of cable-steers, also available from both major manufacturers, makes them the tool of choice for those working in and out of heavy cover, such as racks, rocks and trees. Steering response is immediate and precision is entirely under the operator’s control. An illuminated arrow at the top of the shaft indicates which direction the prop is thrusting at all times.

It’s reasonable to expect a skilled operator in calm weather to be able to manoeuvre a boat with cable-steering in and out of a maze of obstacles with only centimetres to spare either side of the boat.

Because there’s no servo drive for the shaft to key in, more convenient methods of raising and lowering the motor are also used. Sophisticated cantilever mounts enable these motors to be deployed and stowed with minimal effort by just pulling on a cord. Spring-loaded, tensionable mounts also provide considerable ‘give’ before damage is done when the motor strikes an obstruction.

There are, however, also disadvantages. Cable-steer pedals are higher than servo counterparts to allow for the mechanical leverage, which may lead to some operator discomfort.

To counteract propeller torque transferred up the shaft (quite significant in the higher-thrust motors), the operator must keep their foot on the pedal whenever the prop is going around. That can get awfully tiring over long periods.

To reduce ‘mono-leg fatigue’ some enlightened boat builders have built a recess in the casting deck to flush-mount the pedal at a less tiring level. The alternative is to sit on a pedestal chair or use a ‘bum seat’ on a pedestal to spread the load and reduce fatigue.

Those used to servo controls will often find cable-steer somewhat irritating at first but often warm to the system when called on to make tight, precise manoeuvres around heavy structure.

HOW MUCH POWER?

More is better!

While even a 24lb or 30lb thrust electric will successfully propel a 4.5m boat when there’s no current or wind, anglers live in a world dominated by wind and moving water. The worse the conditions are, the more you’ll be grateful for that extra grunt.

As a general guide, motors to 30lb thrust are fine for canoes, punts and dinghies to around 3.5m. Just don’t expect too much in way of precise control when the wind is blowing over about 15kt or a spring tide is running hard. Not that you should be out in conditions much worse than that.

Boats of 3.5-4.5m go well with electrics from 40-55lb, but from there up you’re looking at 24-volt systems and as much thrust as you can apply.

SHAFT LENGTH

Whether it’s a bow-mount or transom design, the length of the shaft should enable the propeller to be under the water at all times, even during a heavy chop or with an inordinate load at the other end of the boat.

Shaft lengths seem to vary from about 30”-60” (sorry, they’re all US measurements) so there’s a fair chance the right shaft is around for your needs. As a rough guide, measure from the deck where the mount will be straight down to a point roughly 15” under the deepest point of the hull.

MOUNTING

It can be a fairly daunting experience to start drilling holes on a boat’s foredeck. Optimum mounting position should be somewhere from the exact point of the bow to about 50cm back on either side – which side doesn’t really matter.

The major thing to remember is to mount so the motor can be freely deployed and stowed from the preferred position. When deployed the propeller should have unobstructed swivelling freedom on the shaft. When stowed, the full length of the motor should intrude as little as possible into the cockpit. There’s usually some way of mounting the thing so that it runs roughly parallel with the boat’s gunwale yet is protected from damaging spray.

Retractable mounts, available as accessories from both manufacturers, allow the removal of the motor for storage and can be fitted with padlocks for added security. You can remove the electric for a day’s skiing with the family and just slide it back on for a fishing trip.

FRESH OR SALT?

While most electrics have been designed for freshwater use for the huge US bass market, both manufacturers offer models which are designated ‘saltwater’. These are more expensive and are available in tiller-steer, servo-steer and cable models from both makers.

All saltwater models offer extra protection in the form of better paint treatment and component/electrical coatings designed to resist the more corrosive marine environment. Zinc anodes also provide additional protection against galvanic corrosion and are available as accessories.

Can freshwater motors be used safely in the salt? Most definitely, but any manufacturer’s warranty they carry will be voided by saltwater use. So you have a decision to make: buy a cheaper freshwater motor and take the risk, or fork out for a saltwater motor with a warranty.

Facts

BATTERIES

Electrics of any size need to be powered by a separate battery to the engine’s cranking battery – a marine deep-cycle battery which can withstand constant flattening and recharging without developing a ‘memory’ which prevents it from being fully recharged.

A deep-cycle 12-volt battery of at least 100 amp hours is the minimum. It should be recharged as soon as possible after use. If the discharged battery is left for any length of time before recharge, irreversible damage can be done when that ‘memory’ sets in.

Electrics draw appreciable current, so additional wiring needs to be substantial, at least 6-gauge (about 16 square millimetres) and heavily insulated. Anderson clips ($30-$50 a pair from auto electricians), or some other equally effective foolproof join, should be used if the wiring needs to be detached. To prevent nasty overloads you should also consider adding a 40-amp circuit-breaker into the system.

Many owners, especially tournament anglers using twin-battery systems of 12 or 24 volts, have invested in onboard charger systems so at the end of a day’s fishing they can simply plug an extension cord into the boat and charging of all batteries takes care of itself. Expensive, but handy.

1. Electric motors open up whole new fishing vistas, including ‘electric-only’ waterways. These anglers are trolling with the transom-mount motor, while the bow-mount is ready to go to work when they begin casting.

2. Phil and Jesse Lomas work a weedbed under autopilot electric power, leaving the motor to do the steering while they cast.

3. There’s always some way you can fit a bow-mount. The author’s MotorGuide stowed on the foredeck of his Quintrex 3.9m dinghy.

4. This freshwater-rated 54lb cable-steer MotorGuide has been operating 2.5 mostly in saltwater, without major dramas. However, all bets are off when it comes to warranty claims, so it’s your call.

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