Difference Between Dual Steering and Single Steering on an Outboard Motor

The difference between dual steering and single steering on an outboard motor is greater than realizing you have more than one motor to steer. There are differences in how the motors are installed on the boat. There are also differences in how the motors are connected and how each reacts to the water.

  1. Steering Coupler

    • There is a steering coupler between the outboards on a dual steering system. The motors are first aligned so they are straight ahead. The best way to ensure the motors are both straight ahead and aligned requires a technician to take a measurement. The distance between the centers of the holes on the steering arm brackets is measured and must equal the distance between the centerlines of the propeller shafts. The single steering system does not require a steering coupler.

    Trim Tab Adjustment

    • Single-engine, single-steering boats pull in the direction in which the motor's propeller turns, as the torque from the propeller is transferred to the boat. Even twin-engine boats with counter rotating props pull to one side or the other -- minor differences in throttle adjustments make one engine dominant. To compensate for this effect on the steering, the trim tab on the single motor is turned in the direction the boat pulls to compensate for this. On a dual steering setup, the rear edge of the trim tab on both motors is turned the same amount in the same direction -- the direction to which the boat pulls, rather than in opposite directions.

    Installation

    • Two motors, mounted too close together, will restrict each others' ability to turn from side to side, making steering difficult. This means that, depending on the motor, each must be mounted the same distance from the centerline of the boat's stern; that is the center of the back of the boat. Once the motors are mounted, the steering cable from the helm can run down either side of the boat. If the cable runs down the port, or left side of the boat, the cable connects to the port engine. If it runs down the starboard -- the right side -- it connects to the starboard engine.

    Operating

    • Aside from the higher speeds and enhanced operating costs, twin-engine installations require multiple throttles or throttle-shift controls. These may, at first, complicate things for the operator unfamiliar with multi-engine setups. With practice, the operator will gain greater control over the boat's movement, using subtle combinations of throttle and steering settings to assist in both docking and station-keeping -- the ability to hold the boat in a specific place when needed.