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About TMS

Autopilot Drives

The marine autopilot drive is the part that moves the rudder. Hydraulically steered boats use a reversible hydraulic pump, while mechanically steered boats use a variety of rotary and linear drive solutions.

Hydraulic pumps are generally available in three sizes, small, medium and large. This represents the flow rate of the pump, that is how fast it can move the rudders. This is a function of the volume of the steering cylinder. When choosing a hydraulic pump, knowing the volume of the cylinder is great, but usually experience lets us specify a pump that is appropriate for your vessel.

For smaller power boats, up to about 30 feet, the small hydraulic pump will work. In the Furuno line up this is the HRP10-12, for Simrad this is the RPU80 and for Raymarine this would be the Type 1. For medium sized boats, less than 40 feet, the medium pump is usually required. For Furuno, this is the HRP17-12, for Simrad this is the RPU160 and for Raymarine this is the Type 2. For larger vessels, over 40 feet it is sometimes necessary to use a large hydraulic pump. For Furuno this is the HRP75-12, for Simrad this is the RPU-300 and for Raymarine this is the Type 3.

On large boats with power steering, a small pump can be added into the slave cylinder. For solenoid steered boats, no pump is required as the pilot will simply control the solenoids in parallel. For "Go-Fast boats with continuous running hydraulic pumps, an autopilot valve is required.

For cable steered stern drive boats there is exactly one good solution, the rotary drive Simrad AP14R. This revolutionary pilot replaces the steering sytem in most Merc sterndrive boats.

For sailboats and mechanically steered inboards there are many solutions. The best set up on a sailboat is a hydraulic linear drive from Simrad, such as the HLD350 and the HLD2000. The below deck mounted devices require correct geometry to work properly and last. When all else fails, convert the boat to hydraulic steering and use a reversible hydraulic pump.

Recommended Products

Technical Marine Support recommends these products based on Reliability and Performance: