SeaStar HC5312-3 Inboard Hydraulic Steering Cylinder — 7" Stroke, 7.2 cu. in.
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SeaStar HC5312-3 Inboard Hydraulic Steering Cylinder
The SeaStar HC5312-3 is a heavy-duty hydraulic steering cylinder designed for inboard-powered vessels with single or dual rudder configurations. With a 7-inch stroke and 7.2 cubic inch displacement, it delivers smooth, precise steering response suited to a wide range of inboard applications.
The HC5312-3 features two-axis articulation, allowing the cylinder to flex with the rudder's natural movement — reducing stress on the steering system and extending service life. Bleeder fittings are included, simplifying air purging during installation and routine maintenance.
An integrated autopilot interface port allows straightforward connection to compatible autopilot systems without additional adapters on most installations.
Key Specifications
- Model: HC5312-3
- Application: Inboard
- Stroke: 7 inches
- Displacement: 7.2 cubic inches
- Compatible Reference: BA125-7ATM
- Seal Kit: HP6023 (sold separately)
- Rudder Compatibility: Single and dual rudder
- Articulation: Two-axis
- Bleeder Fittings: Included
- Autopilot Interface: Yes
- Weight: 2.42 kg (5.34 lbs)
Best Use Cases
- Inboard vessels with single or dual rudder steering requiring a full hydraulic cylinder replacement or upgrade
- Boats where two-axis articulation is needed to accommodate rudder geometry or reduce system stress
- Installations where autopilot integration is planned or already in place
- Full hydraulic steering system builds on inboard-powered cruisers, sportfishers, and workboats
In the Box
- HC5312-3 Hydraulic Steering Cylinder with bleeder fittings installed
Note: The HP6023 seal kit is recommended as a service item and is available separately. Always follow the manufacturer's installation guide and consult a qualified marine technician for installation.
Parts Desk Insights
This cylinder is the go-to choice for inboard rudder applications where two-axis articulation is required — particularly on twin-rudder vessels or installations where the cylinder mount angle doesn't align perfectly with the rudder arm. The included bleeder fittings are a practical advantage during commissioning. Stock the HP6023 seal kit alongside this unit for customers doing a full service or rebuild. Before ordering, confirm the customer's helm pump displacement matches the 7.2 cu. in. cylinder rating, and verify rudder arm geometry to ensure correct stroke utilization. For dual-rudder setups, confirm whether a second cylinder or a tie-bar arrangement is being used.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.