28–57mm CB887 Watertight Anchor Releaser for Commercial Ship Emergency Anchor Chain Release System

Watertight Screw-Type Anchor Chain Releaser | CB 887-1977 for Legacy Submarine Systems

Product Overview

The CB 887-1977 watertight screw-type anchor chain releaser is a mechanical emergency release assembly intended by the original standard for submarine anchor arrangements. It uses a rotating shaft, trapezoidal screw, slider, release hook, locking parts, and a packed stuffing-box structure to retain the anchor chain in the normal condition and to release it through a controlled manual operating sequence when required.

The legacy CB 887-1977 size series covers anchor chain diameters from 28 to 57 mm. It should be treated as a replacement, repair, or drawing-controlled product rather than a general commercial-ship anchor releaser. CB 887-2007 superseded the 1977 edition, revised the chain-size series, added a non-watertight type, and introduced a quantitative watertightness requirement. The approved vessel drawing, installation interface, operating direction, test scope, and authority or class requirement must therefore be confirmed before quotation and production.

Quick Specifications

• Product type: Watertight helix / screw-type anchor chain releaser → mechanical retention and controlled emergency release across a watertight boundary.
• Standard basis: CB 887-1977 legacy configuration → the original standard scope is limited to submarine applications, not ordinary commercial ships.
• Legacy chain diameter range: 28 / 31 / 34 / 43 / 49 / 53 / 57 mm → select by the existing approved installation drawing and chain connection geometry.
• Current-standard note: CB 887-2007 supersedes the 1977 edition → new projects should confirm whether the current 28 / 32 / 34 mm QS or QF configuration is required.
• Watertightness reference (CB 887-2007): stuffing-box leakage test at not less than 0.4 MPa static water pressure → apply to a legacy supply only when included in the approved test specification.
• Operating mechanism: rotating shaft + trapezoidal screw + slider + release hook → manual operation should be checked for smooth movement and clear open / lock direction marking.
• Material concept: mixed steel, stainless-steel, brass, bush, and packing components → final material grades follow the approved BOM, not a single generic material description.
• Inspection focus: dimensions, materials, surface condition, weld quality where applicable, watertightness, operating flexibility, marking, and delivery documentation.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm the required standard revision and service basis: legacy CB 887-1977 replacement / repair, or current CB 887-2007 design.

Step 2: Confirm anchor chain diameter, original model marking, chain-end connection, and the existing installation or vessel drawing. Note that the current standard changed the legacy 31 mm size to 32 mm.

Step 3: Confirm watertight or non-watertight configuration, boundary pressure, test pressure, holding time, leakage acceptance, and witness requirement.

Step 4: Confirm installation interface, operating shaft direction, available operating clearance, release direction, surrounding structure, and access for inspection and maintenance.

Step 5: Confirm the approved material list, packing type, lubrication points, coating system, material traceability, maker documentation, and any class or authority inspection scope.

Step 6: Provide quantity, application vessel type, replacement photos, original drawing or dimensions, delivery destination, and required delivery time.

Structure

Main body | Release hook | Large shaft | Small shaft | Locking catch | Compression nut | Compression sleeve | Packing | Stuffing-box body | Bush | Trapezoidal screw | Slider

Watertightness, Mechanism & Quality Advantages

• The packed stuffing-box arrangement provides a defined sealing interface around the operating shaft when a watertight configuration is specified.
• The trapezoidal screw converts shaft rotation into controlled slider movement, allowing the release hook to be disengaged through a deliberate mechanical operating sequence.
• The locking catch and marked open / lock direction help reduce unintended operation; the final locking and operating arrangement must match the approved drawing.
• Functional materials should be selected by component duty: structural strength for the body and hook, corrosion and wear resistance for shafts, suitable bearing / thread materials for bushes and screw parts, and approved packing for the stuffing box.
• Inspection should cover material documentation, dimensions, surface defects, weld quality where applicable, lubrication, marking, smooth rotation, leakage testing, and packing / delivery records according to the agreed scope.
• For legacy replacement work, dimensional interchangeability and operating access are more important than generic catalogue compatibility; the original installation drawing should control production.

Custom Attributes

• Standard: CB 887-1977 → legacy watertight screw-type anchor releaser for submarine applications.
• Service Status: Legacy / replacement basis → current newbuilding projects should review CB 887-2007 or another applicable standard.
• Chain Diameter: 28-57 mm legacy series → confirm exact original size and chain-end geometry.
• Watertightness: Current-standard reference of 0.4 MPa static water pressure → legacy test scope, holding time, and acceptance to be stated in the order.
• Mechanism: Trapezoidal screw and slider → controlled manual release through shaft rotation.
• Installation Interface: To be confirmed → provide approved GA, boundary detail, operating direction, and available clearance.
• Materials: Multi-material assembly → component grades and substitutions require approved BOM confirmation.
• Surface Treatment: Lubricated friction surfaces + specified protective coating → final coating follows the approved project system.
• Certificate Requirement: According to contract → maker certificate, material documents, test report, class witness, or authority approval to be confirmed before quotation.

How It Works

Anchor chain is connected to the release hook → Locking parts and the screw mechanism retain the hook in the normal condition → Operator turns the shaft / handwheel in the marked release direction → The trapezoidal screw drives the slider and disengages the hook → Anchor chain is released according to the approved operating procedure → The assembly is inspected, serviced, and reset after operation

Applications

Legacy submarine anchor systems | Repair and replacement projects | Drawing-controlled watertight anchor chain release arrangements | Spare assemblies matching original CB 887-1977 installations

Certifications & Advantages

Certificates and third-party inspection can be arranged according to the contract, approved inspection scope, material traceability requirement, and class or authority acceptance procedure. They are not included by default.

Certification: CCS, NK, BV, ABS, DNV, LR, KR, IRS, RS, RINA, CRS, Makers Test Certificate. Available upon request and subject to project requirement and class / authority approval.

Drawing & Photos

FAQ

Q1: Is CB 887-1977 suitable for bulk carriers, tankers, or other ordinary commercial ships?

A1: Not by the stated scope of the standard. CB 887-1977 was intended only for submarine applications. A commercial-ship project should use the vessel designer’s approved arrangement and confirm a suitable standard, such as CB/T 4219-2013 for certain small- and medium-vessel simple anchor releasers or CB/T 3143-2013 for larger dog-type chain releasers, where applicable.

Q2: What changed in CB 887-2007 compared with CB 887-1977?

A2: The 2007 edition superseded the old standard, added a non-watertight type, removed the legacy 43 / 49 / 53 / 57 mm sizes, changed 31 mm to 32 mm, and added a quantitative watertightness requirement and test method. The correct revision must be agreed before quotation.

Q3: What information is essential for a replacement quotation?

A3: Provide the original model or nameplate, chain diameter, approved drawing, installation and operating-side photos, watertight boundary requirement, test pressure and witness scope, material / coating requirements, quantity, destination, and delivery schedule.