Bulwark Mounted Closed Chock for Mooring and Towing | ISO 13729 Type B Cast

Product Specification

Bulwark Mounted Closed Chock for Mooring and Towing | ISO 13729 Type B Cast Steel Rope Guide

Product Overview

The ISO 13729 Type B bulwark mounted closed chock is a cast steel rope guide used on the ship side to lead mooring or towing ropes from inboard to outboard while keeping the rope path controlled through a closed opening. It is selected for ship mooring and towing stations where wire rope or synthetic rope needs a smooth, protected contact radius at the bulwark opening.

Type B is the bulwark-mounted arrangement within the supplied ISO 13729 closed chock data. The chock surface radius is designed around a wire-rope bending ratio of not less than twelve times the wire rope diameter as stated in the supplied information. Final selection should be checked together with rope type, rope diameter, SWL marking, bulwark structure, welding detail, local reinforcement, surface treatment, and classification requirement.

Quick Specifications

• Product type: Bulwark mounted cast steel closed chock → closed ship-side rope passage for mooring and towing arrangements.
• Standard and type: ISO 13729 Type B → used when the vessel drawing specifies a bulwark-mounted closed chock.
• Nominal size range: 250 × 200 × 214 to 500 × 400 × 525B → covers different opening sizes, depths, and bulwark arrangements.
• SWL range from supplied table: 226 to 1413 kN / 23 to 144 t → SWL marking should be agreed between user and manufacturer according to actual loading condition.
• Recommended wire rope diameter: 18 to 44 mm → used as an initial selection reference, not a substitute for vessel mooring or towing calculation.
• Material options: cast C-Mn steel, cast stainless steel, or special steel for icebreaker projects → final grade and certificate scope should be confirmed before production.
• Installation form: bulwark mounted and welded → welding leg length, local reinforcement, and ship-side structure must be checked by the shipyard or design office.
• Surface treatment: Sa 2.5 blasting + epoxy shop primer, polished stainless steel, or customized finish → final coating follows vessel specification and service environment.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm ISO 13729 Type B bulwark mounted cast steel closed chock and the required nominal size L × H × D according to the vessel drawing.

Step 2: Confirm application: mooring, towing, replacement chock, ship-side rope lead, wire rope arrangement, or synthetic rope arrangement.

Step 3: Confirm SWL requirement, rope diameter, rope material, rope lead direction, expected contact angle, and whether the supplied SWL table is accepted for the project.

Step 4: Confirm bulwark opening, installation height, welding interface, welding leg length Z1 / Z2, local reinforcement, and available maintenance space.

Step 5: Confirm material grade: cast C-Mn steel, cast stainless steel, or special steel for ice-class / icebreaker projects when specified.

Step 6: Confirm surface treatment, coating system, polishing requirement, NDT / inspection scope, material certificate, class certificate, and witness inspection requirement.

Step 7: Provide quantity, delivery destination, required delivery time, project drawing, reference photos, and any customer-specific marking or acceptance requirement.

Structure

Cast steel closed chock body | Bulwark-mounted rope opening | Smooth rope-contact radius | Wire-rope bending-radius surface | Welded ship-side connection area | Reinforced cast wall | Surface treatment according to project requirement

Casting, Rope-Contact & Engineering Advantages

• Closed chock geometry helps control the rope path from inboard to outboard and is useful where the ship-side arrangement requires a defined rope passage instead of an open fairlead.
• The rounded chock surface is important for wire rope use because the supplied description states a bending-ratio basis of not less than twelve times the wire rope diameter.
• Cast C-Mn steel construction is suitable for integral chock geometry with continuous curved rope-contact surfaces; final material grade and mechanical properties should be confirmed by order specification.
• Rope-contact surfaces should be dressed, ground, and checked after casting to reduce burrs, sharp edges, and local contact points that may damage wire rope or synthetic rope.
• Bulwark mounting transfers rope reaction forces into the ship-side structure; the shipyard or design office should confirm local reinforcement, weld detail, and surrounding hull structure.
• For stainless steel or special steel versions, surface finishing, corrosion exposure, polishing area, and material traceability should be confirmed before quotation.
• NDT, material certificate, maker certificate, and class witness inspection can be arranged according to project requirement, but they should not be treated as default scope unless agreed in the order.
• The page keeps SWL separate from wire rope breaking load, proof load, and test load to avoid incorrect engineering interpretation.

Custom Attributes

• Standard: ISO 13729 → use when the vessel drawing or owner specification requires ISO closed chock dimensions.
• Type: Type B bulwark mounted → selected for ship-side / bulwark installation instead of deck-mounted arrangements.
• Nominal Size: 250 × 200 × 214 to 500 × 400 × 525B → select by opening size, rope path, SWL, and available bulwark structure.
• SWL: 226 to 1413 kN from supplied table → final marking should follow project agreement and actual loading condition.
• Recommended Wire Rope Diameter: 18 to 44 mm → initial reference for selection; actual rope compatibility should be confirmed by vessel arrangement.
• Material: Cast C-Mn steel / cast stainless steel / special steel → final grade, heat treatment, and certificate scope should be confirmed before production.
• Surface Treatment: Sa 2.5 blasting + epoxy shop primer / polished stainless steel / customized finish → final coating follows vessel painting specification.
• Installation: Bulwark welded → welding leg Z1 / Z2 and local reinforcement should be checked against the ship drawing.
• Certificate Requirement: Available according to order scope → maker certificate, material certificate, class certificate, or witness inspection should be confirmed before quotation.

How It Works

Mooring or towing rope approaches the ship-side bulwark chock → Rope passes through the closed cast-steel opening → Smooth radius surface guides the rope from inboard to outboard → Rope reaction force is transferred through the cast body and welded bulwark structure → Inspection, marking, and coating are completed according to project requirement

Applications

Ship-side mooring stations | Towing rope lead arrangements | Wire rope mooring systems | Bulwark rope openings | Cargo ships | Tankers | Bulk carriers | Offshore support vessels when project-approved | Newbuilding and replacement projects

Certifications & Advantages

Certificates can be arranged according to project requirement, inspection scope, material traceability, and class society approval procedure.

Certification: CCS, NK, BV, ABS, DNV, LR, KR, IRS, RS, RINA, CRS, Makers Test Certificate.

Drawing & Photos

FAQ

Q1: Why is Type B described as a bulwark mounted closed chock?

A1: In the supplied data, Type B refers to the bulwark-mounted arrangement. It is installed on the ship side to guide mooring or towing rope from inboard to outboard through a closed opening.

Q2: Is the listed SWL the same as rope breaking load or test load?

A2: No. The table lists SWL values for the chock selection and marking basis. SWL should not be rewritten as rope breaking load, proof load, or test load unless the project drawing or approval document clearly defines that relationship.

Q3: What should be confirmed before ordering this ISO 13729 Type B closed chock?

A3: Confirm nominal size, SWL, recommended rope diameter, bulwark installation drawing, weld leg, local reinforcement, material grade, surface treatment, quantity, certificate scope, delivery destination, and required delivery time.