ISO 4845:2023

Ships and marine technology - Combined rigging for deep-sea mooring

This document specifies types, dimensions, tests and other technical requirements for combined rigging used for deep-sea mooring (hereinafter referred to as “combined rigging”). This document is applicable to the combined rigging consisting of high modulus polyethylene (HMPE) fibre ropes, mooring chains, and shackles used for mooring and positioning offshore structures with depths of 1 000 m to 5 000 m.

Navires et technologie maritime — Gréement combiné pour l'amarrage en haute mer

General Information

• Status: Published
• Publication Date: 09-Mar-2023
• 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 3 - Outfitting
• Current Stage: 6060 - International Standard published
• Start Date: 10-Mar-2023
• Due Date: 09-Apr-2023
• Completion Date: 10-Mar-2023

Overview - ISO 4845:2023 (Combined rigging for deep-sea mooring)

ISO 4845:2023 specifies types, dimensions, tests and technical requirements for combined rigging assemblies used to moor and position offshore structures in water depths of 1 000 m to 5 000 m. The standard covers combined rigging made of HMPE (high modulus polyethylene) fibre ropes, mooring chains, and shackles, and sets minimum performance, design and testing expectations to ensure long-term reliability for deep‑sea mooring operations.

Key topics and technical requirements

• Scope and components: Defines combined rigging as assemblies of HMPE fibre rope, mooring chain and shackles, with thimbles and protective layers at rope ends.
• Design rules:
  • Strength design must ensure the fibre rope and chain meet minimum breaking strength (MBS) at end of service life.
  • Strength ratio between mooring chain and fibre rope: 1.05–1.10. End‑link size = 1.2 × common link; shackle size = end‑link size.
  • Length design must account for fibre rope creep, keep the rope below the surface during service, and avoid seabed friction.
• Fibre rope specifics:
  • Rope structure: core rope + particle‑resistant isolating layer + protective layer + thimbles.
  • Raw HMPE tenacity ≥ 2 500 MPa; core rope minimum tenacity ≥ 1 300 MPa; protective layer (if polyester) ≥ 730 MPa.
  • Protective layer thickness ≥ 7.0 mm; MBS values range by size (examples in the standard).
• Mooring chains and shackles: Material grade and mechanical performance must comply with ISO 20438:2017 (material, breaking load, chain/studless design, and D‑type shackle references).
• Performance & service life: Assemblies designed for a minimum service time of 10 years and component interchangeability.
• Testing and inspection:
  • Fibre rope tests, MBS, tenacity, anti‑particle penetration and creep per ISO 18692‑3.
  • Chain and shackle mechanical tests per ISO 20438 and classification society rules.
• Marking & documentation: Permanent marking (manufacturer, specs, MBS, date), plus test reports, dimensional and material reports, and a certificate with serial number.

Applications and who uses this standard

• Offshore engineers and mooring system designers specifying combined rigging for deepwater floating platforms, FPSOs, production units and research moorings.
• Manufacturers and suppliers of HMPE ropes, mooring chains and shackles ensuring compliance with design, test and marking requirements.
• Classification societies, shipyards, asset owners and maintenance teams validating performance, interchangeability and service life for deep‑sea mooring assemblies.

Related standards

• ISO 18692‑3 - Fibre ropes for offshore stationkeeping (HMPE)
• ISO 20438:2017 - Offshore mooring chains

Keywords: ISO 4845:2023, combined rigging, deep‑sea mooring, HMPE fibre rope, mooring chain, shackles, ISO 18692‑3, ISO 20438.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4845
First edition
2023-03
Ships and marine technology —
Combined rigging for deep-sea
mooring
Navires et technologie maritime — Gréement combiné pour
l'amarrage en haute mer
Reference number
© ISO 2023
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
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or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design . 1
4.1 Structural types of combined rigging . 1
4.2 Combination design. 2
5 Performance . 2
5.1 Overall performance . 2
5.2 Fibre ropes . 3
5.2.1 Composition . 3
5.2.2 Fibre rope performances . 3
5.2.3 Typical types . 3
5.3 Mooring chains . 4
5.3.1 Mooring chains performances . 4
5.3.2 Typical types . 4
5.4 Shackles . 5
5.4.1 Shackles performances . 5
5.4.2 Typical types . 5
6 Test . 6
7 Marking and documents delivered .7
7.1 Marking . 7
7.2 Technical documents . 7
Annex A (normative) Ratio of fibre rope and mooring chain . 8
Annex B (informative) Corrosion and wear allowances of mooring chain and connecting
parts . 9
Annex C (informative) Types of thimbles .10
Bibliography .11
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 4, Outfitting and deck machinery.
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iv
INTERNATIONAL STANDARD ISO 4845:2023(E)
Ships and marine technology — Combined rigging for
deep-sea mooring
1 Scope
This document specifies types, dimensions, tests and other technical requirements for combined
rigging used for deep-sea mooring (hereinafter referred to as “combined rigging”).
This document is applicable to the combined rigging consisting of high modulus polyethylene (HMPE)
fibre ropes, mooring chains, and shackles used for mooring and positioning offshore structures with
depths of 1 000 m to 5 000 m.
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.
ISO 18692-3, Fibre ropes for offshore stationkeeping — Part 3: High modulus polyethylene (HMPE)
ISO 20438:2017, Ships and marine technology — Offshore mooring chains
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Design
4.1 Structural types of combined rigging
The combined rigging consists of fibre ropes, mooring chains and shackles, as shown in Figure 1.
Key
L length of the outlet end of mooring chains which connects with windlasses
L length of the middle part of combine rigging which is fibre rope
L length of the end of mooring chains which connects with anchors
1 shackle
2 mooring chain
3 fibre rope
4 thimble
Figure 1 — Combined rigging diagram
4.2 Combination design
4.2.1 The strength design of the combined rigging shall meet the following requirements:
a) The strength of the fibre rope shall meet the minimum breaking strength at the end of service time.
b) The ratio of the fibre rope and mooring chain shal
...