ISO 13733:2020

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 13733
ISO/TC 8/SC 4
Ships and marine technology —
Secretariat: SAC
Ship's mooring and towing fittings —
Voting begins on:
2020­05­27 Universal fairleads with upper roller
Voting terminates on:
Navires et technologie maritime — Corps-morts et ferrures de
2020­07­22
remorquage de navires — Chaumards universels avec rouleau
supérieur
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 13733:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

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ISO/FDIS 13733:2020(E)

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© ISO 2020
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ii © ISO 2020 – All rights reserved

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ISO/FDIS 13733:2020(E)

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 . 1
5 Dimensions . 2
6 Materials . 2
7 Construction . 2
8 Manufacturing and inspection . 2
9 Marking . 3
Annex A (normative) Basis for strength assessment of universal fairleads .15
Bibliography .20
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ISO/FDIS 13733:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non­governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
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
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
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 13733:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— technical guidelines have been added in 7.3;
— the definition of SWL (3.1) has been reworded;
— the object lines and mark numbers in Figures 1, 2, 3 and 4 have been amended;
— the values of “t” for the vertical roller, lower horizontal and upper horizontal roller in Table 5 (former
Table 3) have been amended;
— the thickness of the bushes and washers have been added in Table 5 (former Table 3);
— the description in Clause A.1 has been amended;
— the dimension line (θ ) in Figure A.2 has been amended;
1
— the descriptions in Clause A.3 have been amended;
— technical information on FEM and strength calculation have been added in A.3.1.
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.
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ISO/FDIS 13733:2020(E)

Introduction
The universal fairlead is a type of ship’s mooring fitting installed on board to lead the mooring rope
from the ship’s inboard to outboard.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 13733:2020(E)
Ships and marine technology — Ship's mooring and towing
fittings — Universal fairleads with upper roller
1 Scope
This document specifies the types, nominal sizes, dimensions and materials, as well as construction,
manufacturing and marking requirements, for universal fairleads with upper roller(s) installed to lead
the mooring rope of a ship.
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
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
Depending on the construction, universal fairleads shall be classified as belonging to one of the
following four types:
a) Type 4R: with one rope-passing opening;
b) Type 5RL: with one rope-passing opening with an additional guide roller on the left side;
c) Type 5RR: with one rope-passing opening with an additional guide roller on the right side;
d) Type 7R: with two rope-passing openings.
4.2 Nominal sizes
The nominal sizes, D , of universal fairleads are denoted by reference to the outside diameter of the
n
main roller, in millimetres, in terms of the nearest number drawn from a basic series of preferred
numbers. For the universal fairleads having the same roller diameter, the code, i.e. 4R, 5RL, 5RR or 7R,
is followed by the nominal size for the different SWLs.
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ISO/FDIS 13733:2020(E)

The nominal sizes are:
140, 160, 180, 200, 250, 300A, 300B, 400A, 400B and 400C.
5 Dimensions
Universal fairleads shall have dimensions and particulars in accordance with Tables 1, 2, 3, 4, 5 and 6,
and Figures 1, 2, 3, 4 and 5.
6 Materials
The following materials shall be used for manufacturing the components of universal fairleads.
2
a) Frame and other plates: weldable steel plates having a yield point of not less than 235 N/mm ,
except for the frames with a rope guide for nominal sizes 400A, 400B and 400C, which shall be
2
made of weldable steel plates having a yield point of not less than 315 N/mm .
2
b) Roller: weldable steel plates having a yield point of not less than 235 N/mm , except for the rollers
for nominal sizes 400A, 400B and 400C, which shall be made of weldable steel plates having a yield
2
point of not less than 315 N/mm , or equivalent steel tubes.
2
c) Axle: carbon steel having a yield point of not less than 345 N/mm .
d) Bush: brass or bronze or equivalent.
7 Construction
7.1 The rollers of the universal fairleads shall be constructed from steel tubes or formed from plate.
7.2 The foundation of the universal fairleads shall be determined by the manufacturer. The foundation
and welding connections to the hull shall guarantee a reliable transmission of the maximum loading of
the universal fairleads to the hull construction without any plastic deformation or cracks.
7.3 The selection of ship’s mooring fittings and mooring lines should take into account the diameter, D,
of surfaces of mooring fittings that are in contact with the mooring line diameter, d, (D/d ratio) to reduce
or mitigate bend ross of strength.
7.4 The tensile strength of mooring rope may be reduced depending on bend radius (D/d ratio)
through the mooring fittings, in accordance with the rope manufacturer’s guidelines.
8 Manufacturing and inspection
8.1 All surfaces of the universal fairleads, including welded surfaces, shall be free from any visible
flaws or imperfections.
8.2 All surfaces in contact with the ropes shall be free from surface roughness or irregularities likely to
cause damage to the ropes by abrasion.
8.3 The universal fairleads shall be coated externally with an anti-corrosion protective finish.
8.4 All rotating parts shall be greased.
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ISO/FDIS 13733:2020(E)

9 Marking
9.1 The safe working load (SWL) for the intended use of the universal fairleads shall be noted in the
towing and mooring plan available on board for the guidance of the shipmaster as specified in IMO
circular MSC/Circ.1175.
9.2 The actual SWL on board shall be determined by considering the foundation and under deck
reinforcement, and it shall be marked on the towing and mooring plan. The actual SWL shall not be over
the SWL in this document.
9.3 The universal fairleads shall be clearly marked with their SWL by weld bead or equivalent. The
SWL shall be expressed in tonnes (symbol 't') and be placed so that it is not obscured during operation of
the fitting.
EXAMPLE SWL XXX t
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ISO/FDIS 13733:2020(E)

Dimensions in millimetres
Key
1 frame with rope guide
2 vertical rollers with housing and washers
3 lower horizo
...