Transmission steering system

Although I initially preferred the rack-and-pinion option, this system did not make it to the implementation stage. The space available in the stern is simply too small and too narrow to make optimal use of a wide-angle geometry. This smart geometry provides very direct steering around midships (where loads are low) and a more indirect, powerful steering at large rudder angles (where loads are highest).

In addition, the drag link from pedestal to rudder, with a length of almost 3 m (10 ft), requires considerable clearance for its movement and therefore a large opening in the aft beam bulkhead.

These constraints provided sufficient reason to abandon the rack-and-pinion system.

In order to retain the wide-angle steering geometry, I decided to switch to a transmission steering system and selected the Danish Jefa system. This system is based on the same principle as rack-and-pinion steering: rotation of the wheel is converted into a push–pull movement. However, instead of a drag link, the motion is transmitted via a torque tube, using gearboxes and levers.

Due to the limited space behind the transom, the proposed position of the bevel reduction gearbox was still too far aft. As a result, the torque tube did not align with the available height beneath the aft cabin bed. This space is also reserved for the water ballast tank, leaving no room for compromise.

The solution was to move the entire rudder assembly 96 mm forward. Consequently, the width of the lower step in the stern was reduced from 374 mm to 278 mm, resulting in a required 210 mm extension of the reduction gearbox shaft.

The bevel reduction gearbox is housed in its own watertight compartment and isolated from the exterior by a sealed roller bearing. The autopilot drive connects at the front of the bevel gearbox, directly below the steering pedestal. The autopilot itself will be installed at a later stage.

I have high expectations of this steering system. The only drawback I foresee is the considerable weight of the bevel reduction gearbox located far aft in the boat.