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Using a Hydraulic GHP Autopilot with a Hynautic Steering System
If the boat that is being equipped with the Hydraulic GHP Autopilot has a Hynautic hydraulic system already installed, there are a few considerations to follow in order to allow the autopilot to perform optimally.
The Hynautic system uses air to pressurize the hydraulic fluid in the steering lines. Hynautic recommends the system be at 25 psi. Unfortunately this amount of pressure will cause issues with the autopilot's components and may blow gaskets and seals. Garmin recommends using around 10 psi for all of our components. We recommend setting the psi to 7 or 8 and at that point, turn the helm. If the helm moves normally, maintain that psi. If the helm does not move normally, the psi can be changed to correct the issue. However, please do not increase the psi too much.
Also, the Hynautic system uses a reservoir which connects to the helm's return line. Since the autopilot's pump needs to connect to the return line, install a T-fitting into the line that returns the fluid back to the helm and connect that to the return line on the autopilot's pump.