Mega quadrant from EdsonAug 22, 2013
Many boats use a quadrant to attach steering cables to the rudder post. And chances are you've slithered into that space in the stern of your boat and inspected, tightened up or had to repair your vessel's quadrant. It's unlikely you've ever gotten anywhere near a quadrant of this size, however. The quadrant shown in the picture was manufactured by Edson International in New Bedford, Mass., for Dutch superyacht builders Royal Huisman. It has a radius of more than 51 inches with a bore to fit a 17-inch diameter sleeve on a carbon fiber rudder post.
Edson further describes the systems like this: "Edson's multi-speed mechanical steering system for this yacht directs the helmsman's touch of the wheel through a gearbox with an integral wheel clutch, and then to the quadrant through a chain and wire arrangement. The gearbox allows the helmsman to adjust the steering wheel sensitivity and power to the conditions at hand, and clutch out the wheels when the autopilot is in use. Edson's advanced system places super sensitive bearings throughout the arrangement, giving the helmsman 'feel' in the wheel."
When it comes to maintenance, most of us are lucky to be dealing with a quadrant several times smaller than this brawny fitting.