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T: +86-156-0511-1716
E: hp018@hpcbkj.com
E: hp018@hpcbkj.com
In Fangong Industrial Park, Dongtai Town, Dongtai City
The Sternpost is a structural backbone of a vessel’s stern, located on the hull’s centerline to connect the keel, bottom structure, and side outer plates. It supports the rudder and propeller while enhancing hull strength.
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Multi-functional structural integration (connection, support, protection).
Adaptability to 3 rudder types (unbalanced, balanced, semi-balanced).
High-strength materials (cast steel, forged steel) for heavy-load bearing.
Customizable designs for vessels of all sizes (10–500,000 DWT).
Parameter | Multi-Support Sternpost (With Propeller Hole) | Double-Support Sternpost (No Rudder Post) | Semi-Suspended Sternpost (No Rudder Post/Bottom Bone) |
Material | Cast steel (ASTM A131) or forged steel | Cast steel/steel plate welding | Forged steel/steel plate welding |
Applicable Rudder Type | Unbalanced rudders (e.g., flat rudders) | Balanced rudders (double-support) | Semi-balanced rudders (semi-suspended) |
Max Bearing Torque | 50–150 kN·m | 100–300 kN·m | 80–250 kN·m |
Applicable Vessel Tonnage | <5,000 DWT (inland/coastal ships) | 5,000–500,000 DWT (ocean-going vessels) | 1,000–50,000 DWT (coastal/passenger ships) |
Overall Length Range | 3–8m | 5–15m | 4–12m |
Key Component Size | Propeller hole diameter: 0.8–2m | Sternpost bottom bone diameter: 0.5–1.2m | Upper support diameter: 0.4–1.0m |
Weight Range | 500kg–5 tons | 2–20 tons | 1–10 tons |
Note: Multi-support sternposts are rarely used in modern seagoing ships due to the decline of unbalanced rudders.
Structural Integrity: Connects the hull’s stern components into a single rigid unit, resisting wave impact and propeller vibration.
Load-Bearing Capacity: Supports the propeller’s weight (up to 50 tons) and the torque from rudder turning (up to 300 kN·m).
Corrosion Resistance: Surface-treated with anti-rust paint (epoxy or zinc-rich coating) and sacrificial anodes for long-term seawater resistance.
Rudder Compatibility: Tailored designs for each rudder type – e.g., double-support sternposts have a reinforced bottom bone to replace the rudder post.
Large Ocean-Going Tankers (100,000+ DWT): Double-support sternposts with forged steel construction bear the weight of large propellers (3–5m diameter) and high rudder torque during port maneuvering.
Coastal Passenger Ferries: Semi-suspended sternposts reduce hull weight (by 15% vs. double-support models) and improve fuel efficiency, while supporting semi-balanced rudders for smooth steering.
Inland Cargo Ships (<5,000 DWT): Cost-effective multi-support sternposts (cast steel) fit unbalanced rudders, adapting to shallow-water navigation and frequent docking impacts.
Multi-Support Sternpost:
Includes a rudder post and sternpost bottom bone, with a propeller hole for unbalanced rudders.
Rarely used today but suitable for retrofitting old inland ships.
Double-Support Sternpost:
No rudder post; relies on a thickened bottom bone to bear loads.
Ideal for balanced rudders (with supports at both rudder blade ends), common in modern large vessels.
Semi-Suspended Sternpost:
Lacks both rudder post and bottom bone; upper end is reinforced to support semi-balanced rudders (no lower support).
Lightweight design for medium-sized ships, reducing hull draft.
Manufacturing Methods:
Large ships: Cast steel (segmented casting) + on-site welding assembly (to handle complex shapes).
Small/medium ships: Steel plate welding (lightweight, low cost) + cast steel hubs/rudder bearings for critical parts.
Installation Process:
Set up a horizontal tire frame on the assembly platform, marking the sternpost contour, axis, and rudder stock centerline.
Hoist sternpost components, align with marks, and open docking grooves for welding.
Weld segments (using submerged arc welding for high strength) and inspect for defects via non-destructive testing (NDT).
Install sacrificial anodes and anti-rust coatings before hull integration.
Engineering Design: Provides 3D structural models (using AutoCAD/SolidWorks) tailored to vessel tonnage and rudder type.
Quality Assurance: Conducts NDT (ultrasonic/magnetic particle testing) for welds and supplies material certificates (ABS/DNV approved).
On-Site Installation: Dispatches engineers to supervise sternpost assembly and alignment with the rudder/propeller system.
Maintenance & Repair: Offers 5-year anti-corrosion maintenance plans, including anode replacement and coating touch-ups.
