Accu-Steer HRP11-12 Hydraulic Reversing Pump Unit 12 VDC

The Accu-Steer HRP11-12 is a 12 VDC hydraulic reversing pump - the component that physically moves your boat's existing manual hydraulic steering when an autopilot tells the pump to. If your boat has manual hydraulic steering (a helm pump turning a steering cylinder on the outboard or rudder) and you want to add an electronic autopilot, you need a reversing pump like the HRP11-12 to translate the autopilot's electronic 'steer left / steer right' command into the hydraulic pressure that physically moves the rudder. The Accu-Steer HRP Series is the long-standing standard for this job - the same product most major autopilot brands recommend or rebrand for their own kit installs on boats already equipped with hydraulic steering.

Which HRP model fits your boat. Accu-Steer makes three pumps in the HRP Series sized to different cylinder volumes. The HRP05-12 outputs 0.5 cu in/sec and fits cylinders up to about 8 cu in - smaller outboard rams on sub-22 ft boats. The HRP11-12 (this product) outputs 1.0 cu in/sec and fits cylinders 10-16 cu in - the typical zone for 22-32 ft outboard-powered center consoles and bay boats running standard Seastar / Baystar-class hydraulic rams. The HRP17-12 outputs 1.7 cu in/sec and fits cylinders up to 18 cu in and beyond - larger inboard sportfishers, sub-50 ft yachts, and any twin-engine outboard rig running matched dual cylinders. Picking the wrong size kills autopilot performance: too small and the rudder responds sluggishly (autopilot loses sea state authority), too large and the rudder slams hard-over on every correction (overshoots heading, fatigues steering hardware). The 1.0 cu in/sec HRP11 is the most commonly-specified pump because the 10-16 cu in cylinder band is by far the most common steering setup on the boats people add autopilots to.

Why Gerotor pumping technology matters. Inside the pump housing is a Gerotor gear assembly - an inner and outer gear with the inner mounted eccentrically inside the outer. As the gears rotate, the space between them changes, pumping fluid through with each rotation. The Gerotor design gives three real-world advantages over the older cheaper vane-pump designs that competing pumps use: (1) Whisper-quiet operation, because the gear meshing creates no impulsive noise - you don't hear the pump clicking on and off as the autopilot makes small corrections. (2) Consistent volumetric output at varying back-pressure - the rudder moves at a predictable speed whether the boat is in flat water or fighting beam seas. (3) Long service life - Gerotor gears wear evenly and slowly, with typical service life measured in thousands of operating hours.

Reversing design. The 'Reversing' in HRP stands for the fact that the pump runs in both directions to move hydraulic fluid both ways through the steering system. The autopilot commands the pump to spin one direction (port rudder), the other direction (starboard rudder), or stop (hold heading). The motor is a brushed DC motor wired through the autopilot's pump-drive output. Older systems used solenoid-valve switching with a one-direction pump - more parts to fail, more lag. The reversing pump is the modern standard.

Pressure relief valve. Built into the pump housing is a 1000 PSI maximum-pressure relief valve. If the autopilot commands hard-over rudder and the cylinder reaches its mechanical end-stop, the pressure relief opens to dump excess pressure back to the reservoir rather than blowing seals or damaging the rudder linkage. Critical safety feature - autopilots occasionally command full hard-over (sea trial calibration, emergency commands, or just wave-driven over-correction in heavy following seas) and the relief valve is what keeps that command from breaking something expensive.

Electrical specs and wiring. 12 VDC nominal, draws 6 amps idle and up to 30 amps under peak load (full hard-over against a stiff cylinder). The wide current range matters for wire sizing - run a #6 AWG minimum from the battery to the pump-drive output, with a 40 amp blade fuse at the battery. The autopilot computer handles the actual pump drive (it's not a simple on/off switch from the autopilot - the computer pulse-modulates the pump to control rudder speed and avoid overshoot). Always wire through the autopilot's specified pump-drive output, never direct from a switch.

What it interfaces with on the autopilot side. The HRP11-12 is electrically driven by the autopilot computer's pump-drive output. That output is standardized across the major autopilot brands (all the major-brand autopilot computers), so the HRP11 works with autopilots from all the major brands. The autopilot installation instructions will call for an Accu-Steer HRP-class pump (or rebadged equivalent from the autopilot vendor - same internal pump in many cases) and will specify the wiring and pump-size selection. Read the autopilot install manual carefully and verify HRP11 is the recommended size for your boat's cylinder capacity before ordering.

What it interfaces with on the hydraulic side. The HRP11 ties into the existing hydraulic steering circuit via four 1/4 NPT pipe ports: two to the cylinder (port and starboard), one to the reservoir, and a return port. Plumbing requires hydraulic-grade fittings (typically 1/4 NPT male to JIC 37-degree flare, mating to whatever the existing hydraulic lines use). Pump-to-steering plumbing kits aren't included - they're typically supplied with the autopilot installation kit or sourced separately based on the existing steering hardware. Confirm port sizes and thread compatibility before plumbing.

Mounting. The HRP11 mounts on its flat baseplate in any reasonably-level location below the steering helm, typically in the bilge or a dedicated electronics compartment. Floor mount only - the pump should not be wall-mounted on a vertical surface (the pump body needs to stay below the reservoir fluid line for proper priming and self-bleeding). Allow 6-8 inches of clearance above the pump for the cooling fan and serviceability. The pump runs warm under heavy duty cycle (long offshore passages) - install in a location with reasonable air circulation, not buried in a sealed bilge compartment.

Quality and serial-number traceability. Accu-Steer test-runs every pump after assembly and assigns a unique serial number with the test results kept on file at the factory. If you need warranty service or a replacement pump in 5-10 years, Accu-Steer can pull the original test record by serial number. That's the kind of quality discipline you don't get from generic hydraulic pump suppliers - and it's why the HRP Series has become the OEM-spec'd autopilot pump for most major brands.

What ships in the box. One Accu-Steer HRP11-12 hydraulic reversing pump unit. Mounting hardware, hydraulic fittings, plumbing lines, wire, fuses, autopilot computer, control head, and rudder feedback sensor are all sold separately and selected to match the specific autopilot system being installed.