ISO 13728:2020

Ships and marine technology - Ship's mooring and towing fittings - Panama chocks

This document specifies the types, nominal sizes, dimensions and materials, as well as construction, manufacturing and marking requirements, for Panama chocks installed to lead the mooring and towing rope of a ship. It is intended for ships passing through the Panama Canal, which are normally assisted through the locks by locomotives using steel towing wires and/or by tug boats. These chocks meet normal mooring requirements and Panama Canal requirements; they are suitable for mooring vessels inside the Panama Canal locks. NOTE The Panama chocks (SWL of 90 tons) for the Panamax Plus and Neopanamax vessels can be replaced by closed chocks (see ISO 13729).

Navires et technologie maritime — Corps-morts et ferrures de remorquage de navires — Écubiers de Panama

General Information

• Status: Published
• Publication Date: 27-Aug-2020
• ICS: 47.020.50 - Deck equipment and installations
• Technical Committee: ISO/TC 8/SC 4 - Outfitting and deck machinery
• Drafting Committee: ISO/TC 8/SC 4/WG 4 - Ship's mooring and towing fittings
• Current Stage: 9060 - Close of review
• Completion Date: 04-Mar-2031

Relations

• Consolidated By: ISO 17751-1:2023 - Textiles - Quantitative analysis of cashmere, wool, other specialty animal fibres and their blends - Part 1: Light microscopy method
• Effective Date: 06-Jun-2022
• Revises: ISO 13728:2012 - Ships and marine technology - Ship's mooring and towing fittings - Panama chocks
• Effective Date: 30-Sep-2017

Overview

ISO 13728:2020 - "Ships and marine technology - Ship's mooring and towing fittings - Panama chocks" specifies design, material, manufacturing, inspection and marking requirements for Panama chocks used to lead mooring and towing ropes. Intended primarily for ships transiting the Panama Canal, the standard covers both deck‑mounted (Type A) and bulwark‑mounted (Type B) chocks in nominal opening sizes 310 mm and 360 mm, and defines safe working load (SWL) practices compatible with canal and normal mooring operations.

Key topics and requirements

• Types & sizes
  • Type A: deck‑mounted; Type B: bulwark‑mounted.
  • Nominal opening widths: 310 and 360 mm.
• Materials
  • Steel casting with yield point ≥ 235 N/mm²; carbon ≤ 0.23% for weldability.
• Load & strength assessment
  • Load cases include individual horizontal and vertical loadings (not assumed simultaneous).
  • Annex A gives the basis for strength assessment, including bearing radii, opening area minima and FEM analysis rules.
  • Stress criterion: combined stress limited to 85% of material yield under SWL.
• SWL (safe working load)
  • Example reference SWLs are provided (e.g., ~48 t, 70 t, 79 t depending on type/size), but the standard notes these are reference values; actual SWL must account for foundation and under‑deck reinforcement and be recorded in the ship’s mooring/towing plan.
• Construction & manufacture
  • Foundations and weld connections must transmit maximum loading without plastic deformation or cracking.
  • Surfaces contacting ropes must be smooth; all surfaces free from visible flaws.
  • External anti‑corrosion coating required; minimum radii for unspecified edges ≥ 25 mm.
• Marking & documentation
  • SWL must be shown on the towing and mooring plan (per IMO MSC/Circ.1175) and marked on the chock or foundation in tonnes.

Applications and users

ISO 13728:2020 is used for:

• Shipbuilders and outfitting contractors specifying and installing ship mooring fittings.
• Manufacturers of Panama chocks and deck hardware.
• Naval architects and marine engineers designing under‑deck reinforcement and foundations.
• Shipowners, ship operators, classification societies and Panama Canal authorities verifying compliance for vessels transiting locks.
• Maintenance and inspection teams ensuring safe operation and correct SWL marking.

Practical use cases include selection of chock types for lock transits, design verification using FEM per Annex A, factory inspection criteria and on‑board marking and documentation for mooring/towing plans.

Related standards and references

• ISO 13729 (closed chocks for larger vessels / Panamax Plus & Neopanamax)
• ISO 4990 (steel castings requirements)
• IMO MSC/Circ.1175 (guidance on shipboard towing and mooring equipment)
• Panama Canal Requirements - OP Notice to shipping No. N‑1‑2019
• IACS UR A2, OCIMF MEG4

Keywords: ISO 13728:2020, Panama chocks, ship mooring fittings, safe working load (SWL), Panama Canal, deck-mounted chock, bulwark-mounted chock, marine technology.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13728
Second edition
2020-08
Ships and marine technology —
Ship's mooring and towing fittings —
Panama chocks
Navires et technologie maritime — Corps-morts et ferrures de
remorquage de navires — Écubiers de Panama
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification . 1
4.1 Type . 1
4.2 Nominal sizes . 2
5 Dimensions . 2
6 Materials . 2
7 Construction . 2
8 Manufacturing and inspection . 2
9 Marking . 2
Annex A (normative) Basis for strength assessment of Panama chocks. 7
Bibliography .12
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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www .iso .org/ iso/ foreword .html.
This document was prepared Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee
SC 4, Outfitting and deck machinery.
This second edition cancels and replaces the first edition (ISO 13728:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— the Scope has been reworded; a NOTE concerning the Panama chock for the Panamax Plus and
Neopanamax vessels has been added;
— the definition of SWL (3.1) has been reworded;
— technical information on FEM has been added in A.3.2.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
The Panama chock is a type of ship’s mooring and towing fitting installed on the shipside to lead the
mooring or towing rope from the ship’s inboard to outboard.
INTERNATIONAL STANDARD ISO 13728:2020(E)
Ships and marine technology — Ship's mooring and towing
fittings — Panama chocks
1 Scope
This document specifies the types, nominal sizes, dimensions and materials, as well as construction,
manufacturing and marking requirements, for Panama chocks installed to lead the mooring and towing
rope of a ship. It is intended for ships passing through the Panama Canal, which are normally assisted
through the locks by locomotives using steel towing wires and/or by tug boats. These chocks meet
normal mooring requirements and Panama Canal requirements; they are suitable for mooring vessels
inside the Panama Canal locks.
NOTE The Panama chocks (SWL of 90 tons) for the Panamax Plus and Neopanamax vessels can be replaced
by closed chocks (see ISO 13729).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
IMO Circular MSC/Circ.1175, Guidance on shipboard towing and mooring equipment
Panama Canal Requirements — OP Notice to shipping No. N-1-2019 — Vessel requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
safe working load
SWL
safe load limit (maximum permissible load) of the fittings used for mooring and towing
4 Classification
4.1 Type
The Panama chock shall be classified by its installation site as belongi
...