By Mike Gridley
For long distance running, an autopilot should be high on your wish list. Not only are they more accurate than human control, they also cut back on the fatigue level when manning the helm for long periods of time.
Whether you are installing a new system or upgrading an old unit, with at least average skills and careful planning this project may be one to take on yourself. In the case of our project boat, I tackled an upgrade of a failed Robertson unit with a new Simrad Autopilot.
Starting at the helm, I made quick work of removing the old control unit, which left a hole in the helm that did not match the new control unit. This meant I had to create a template so a filler plate could be fabricated that would accept the new unit and cover up the existing holes in the helm.
Using the template, the mounting hole was cut for the control unit, the custom mounting plate installed and the control unit set in place. If this had been a new install, just the mounting hole would have been cut into the helm.
Next up was fishing the SimNet cable from the helm to the engine compartment. I lost a full day on this step because the headliner in the salon of the project boat had to be removed for access.
The next task was to remove the old rudder position indicator to make way for the new unit. The transmitter link (or rod) was disconnected, the old signal wire cut and the unit unscrewed.
The new Simrad unit mounted in the same position adjacent to the rudder post. With the rudders amidships, the new transmitter link was connected between the rudder arm and indicator arm using the supplied ball joint connectors. Once connected, the link was adjusted to align the marks on the indicator to set the zero position.
With the new hardware installed, the SimNet cable was fished from the stern into the engine compartment.
The next piece of hardware (or, in this case, electronic) to be installed was the fluxgate compass. The installation location of this is critical to the overall performance of the system. It has to be on the centreline of the boat, as low as possible and as far away from metal or magnetic interference as possible
With limited access to the bilge, I chose a central position under the companionway stairs leading from the galley down and forward to the staterooms. By cutting the riser away from the companionway stairs, fabricating a new one and mounting the Fluxgate Compass to the back of the riser, I was able to install it following the guidelines.
With the compass in place, I headed into the bilge to fish the SimNet cable aft to the engine compartment.
Back in the engine compartment, the SimNet Cables from the control unit at the helm and from the Fluxgate Compass were plugged into a multijoiner. Next, a special SimNet cable was run from the joiner up into a locker in the cockpit along with the rudder position indicator cable, where the original Robertson computer was located. While removing the old computer, I marked the 12-volt power supply wires and the wires leading to the servo motors that would be reused.
Before installing the new computer, I first connected the cable from the udder position indicator, then the SimNet cable from the multijoiner, the two positive and one negative power cables from the existing servo motors on the hydraulic steering pumps, and finally the 12-volt power. Mounting holes were then marked, drilled and the computer mounted.
Having finished connecting everything to the autopilot computer down below, the final task was to install the control unit at the helm. Under the helm, I rigged the 12-volt power cable for the control unit with an inline fuse and connected it to the existing autopilot switch. Finally, the SimNet cable from the engine compartment and the power cable were plugged into the control unit and it was secured in place.
When the system was powered up, all of the components self initiated and reported their status on the control unit display and the autopilot system was ready to be dialled out on the water while underway.
In performing this retrofit, the only step not covered was the installation of the servos and hydraulic pumps that manipulate the steering. Whether your power is outboard, sterndrive or inboard, Simrad offers a line of reversible hydraulic pumps for vessels with hydraulic steering systems.
While this project may seem a little daunting, the advent of the NEMA 2000 standard has made the cabling system for modern electronics more uniform and easier to work with. As well, companies like Simrad and their competitors have a wealth of information online to guide you. But, as always, when you feel a little out of your league, don’t be afraid to call a professional.