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Seastar HC5805 Power Steering Cylinder Kit 2.5" x 9" Stroke

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HC5805
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  • Seastar HC5805 Power Steering Cylinder Kit 2.5" x 9" Stroke
  • Seastar HC5805 Power Steering Cylinder Kit 2.5" x 9" Stroke
$5,746.00
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Description

Seastar HC5805 Power Steering Cylinder Kit 2.5" x 9" Stroke 

Effortless Hydraulic Steering for High-Horsepower Yachts and Commercial Vessels

The Seastar HC5805 Power Steering Cylinder is engineered for high-performance yachts and commercial boats that are typically difficult to steer with conventional systems. Built for use in advanced Seastar Power Steering configurations, the HC5805 delivers responsive, smooth, and virtually effortless steering from dockside maneuvers to high-speed cruising.

Recently reintroduced and now manufactured in the USA, the HC5805 reflects SeaStar Power Steerings commitment to quality, innovation, and marine-grade reliability. With its robust design, integrated safety features, and support for autopilot systems, the HC5805 is a preferred solution for vessels up to 100 feet. The new cylinder will differ in visual aspects.

Key Features & Benefits

✔ High-Horsepower Steering Made Easy – Precision hydraulic response for yachts and workboats that demand control under pressure.

✔ Manual Backup Built In – In the event of power failure, fluid automatically routes to helm for manual override.

✔ Autopilot-Ready – Easily integrates with most autopilot systems via the built-in secondary pump with adjustable flow.

✔ Made in the USA – Now back in production and proudly manufactured domestically.

✔ Semi-Auto Purge Feature – Reduces air during installation or service, cutting down install time and improving reliability.

✔ Streamlined Installation – Fewer components to install—no need for separate filters, engine pumps, or flow control valves.

✔ Energy Efficient Design – On-demand DC power system draws minimal energy and reduces wear on components.

✔ 2-Year Limited Warranty – Confidence backed by Seastar Power Steerings industry-standard support.

Technical Specifications

Specification Details
Model HC5805
Cylinder Type Hydraulic Power Steering Cylinder
Bore Size 2.5 inches
Stroke Length 9 inches
Application Inboard, commercial, luxury yachts
Vessel Size Range Up to 100 ft (planing hulls)
Manual Backup Yes – automatic fluid bypass
Autopilot Integration Built-in secondary pump
Power Supply DC, typically 24V
Country of Manufacture USA
Warranty 2-Year Limited

Vessel Compatibility Guide

Hull Type Max Vessel Length
Displacement Hull (standard) Up to 85 ft (26 m)
Displacement Hull (heavy duty) Up to 60 ft (18 m)
Planing Hulls Up to 100 ft (31 m)

System Advantages

  • Few Components to Spec and Install – Simplifies power steering upgrades or new builds.
  • Integrated Autopilot Pump – Seamlessly connects to most modern helm-based autopilot controllers.
  • 100% Performance, 100% of the Time – Delivers precise oil flow regardless of engine RPM.
  • Minimal Power Draw – Uses power only during steering input (5–10% duty cycle typical).
  • Suitable for Multi-Station Installations – Flexible enough for complex helm setups.
  • Works with SeaStar Tilt Helms and Standard Helms – Broad compatibility for new and existing systems.

We Can Rebuild Your Cylinder

Downloads & Resources

Cylinder Selection Guide by Vessel Type

Cylinder Type Displacement Hulls (Standard) Displacement Hulls (Heavy Duty) Planing Hulls
Single – 9” x 2” Cylinder (HC5801-2) Up to 50’ (15m) Up to 40’ (12m) Up to 65’ (20m)
Twin – 9” x 2” Cylinder (HC5802 & HC5801-2) Up to 75’ (22m) Up to 55’ (17m) Up to 85’ (26m)
Single – 11” x 2” Cylinder (HC5803-2) Up to 60’ (18m) Up to 50’ (15m) Up to 75’ (23m)
Twin – 11” x 2” Cylinder (HC5804 & HC5803-2) Up to 100’ (31m) Up to 70’ (22m) Up to 110’ (34m)
Single – 9” x 2.5” Cylinder (HC5805) Up to 85’ (26m) Up to 60’ (18m) Up to 100’ (31m)

 

Cylinder Technical Specifications

Cylinder Type Displacement Bore Stroke Output Force Max Torque (35° from Center)
Single – 9” x 2” Cylinder (HC5801-2) 21.25 in³ (348cc) 2.0” (51mm) 9” (229mm) 2946 lbsf (13,090 N) 18,900 in-lbs (217 kg/m)
Twin – 9” x 2” Cylinder (HC5802 & HC5801-2) 42.50 in³ (697cc) 2.0” (51mm) 9” (229mm) 5892 lbsf (26,190 N) 37,800 in-lbs (435 kg/m)
Single – 11” x 2” Cylinder (HC5803-2) 26.00 in³ (426cc) 2.0” (51mm) 11” (280mm) 2946 lbsf (13,090 N) 23,140 in-lbs (266 kg/m)
Twin – 11” x 2” Cylinder (HC5804 & HC5803-2) 52.00 in³ (853cc) 2.0” (51mm) 11” (280mm) 5892 lbsf (26,190 N) 46,280 in-lbs (533 kg/m)
Single – 9” x 2.5” Cylinder (HC5805) 37.11 in³ (608cc) 2.5” (64mm) 9” (229mm) 5154 lbsf (22,926 N) 33,065 in-lbs (380 kg/m)

 

hc5801.jpg

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Why Choose the Seastar HC5805?

For captains, installers, and boatyards looking for elite-level steering performance on larger vessels, the HC5805 is a proven, purpose-built cylinder that delivers superior handling with fewer headaches. Backed by Seastar’s engineering excellence and USA-based manufacturing, it’s the go-to solution for effortless hydraulic control—even on the biggest builds.

Choose HC5805 when only the best power steering performance will do.

Questions?

  • No Sales Tax on Purchases Outside of California
  • Buy Now Pay Later with Affirm or PayPal Pay Later
  • FREE Ground Shipping to the Contiguous 48 States
  • Seatech Marine Products, Inc. is an authorized dealer, and service center for Seastar Power Steering

International Customers: We Ship Worldwide, Shipping Cost May Quote Too High on Our Web Site, contact us for a quote.

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Warranty Information

Seatech Marine Products, Inc. is an authorized dealer and service center for Seastar Power Steering. They offer a 2 Year Limited Warranty.
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