Small craft - Hull construction and scantlings - Part 7: Determination of loads for multihulls and of their local scantlings using ISO 12215-5 (ISO 12215-7:2020)

This document defines the dimensions, local design pressures and global loads acting on multihull
craft with a hull length (LH) or load line length of up to 24 m (see Note). It considers all parts of the
craft that are assumed watertight or weathertight when assessing stability, freeboard and buoyancy in
accordance with ISO 12217 (all parts). Scantlings corresponding to the local design pressures are then
assessed using ISO 12215-5.
NOTE The load line length is defined in the OMI "International Load Lines Convention 1966/2005", it can
be smaller than LH for craft with overhangs. This length also sets up at 24 m the lower limit of several IMO
conventions.
This document is applicable to multihulls built from the same materials as in ISO 12215-5, in intact
condition, and of the two following types:
— recreational craft, including recreational charter vessels;
— commercial craft and workboats.
It is not applicable to multihull racing craft designed only for professional racing.
This document is applicable to the structures supporting windows, portlights, hatches, deadlights
and doors.
For the complete scantlings of the craft, this document is intended to be used in conjunction with
ISO 12215-8 for rudders, ISO 12215-9 for appendages of sailing craft and ISO 12215-10 for rig loads and
rig attachment in sailing craft. ISO 12215-6 can be used for additional details.
Throughout this document, unless otherwise specified, dimensions are in (m), areas in (m2), masses
in (kg), forces in (N), moments in (Nm), Pressures in (kN/m2) (1 kN/m2 = 1 kPa), stresses and elastic
modulus in (N/mm2) (1 N/mm2 = 1 MPa).

Kleine Wasserfahrzeuge - Rumpfbauweise und Dimensionierung - Teil 7: Bestimmung der Lasten für Mehrrumpffahrzeuge und ihrer lokalen Dimensionierungen unter Anwendung der ISO 12215-5 (ISO 12215-7:2020)

Dieses Dokument definiert die Abmessungen, lokalen Entwurfsdrücke und globalen Lasten, die auf Mehrrumpfboote mit einer Rumpflänge (LH) oder Länge der Konstruktionswasserlinie von bis zu 24 m wirken (siehe Anmerkung). Es berücksichtigt alle Teile des Wasserfahrzeugs, die bei der Beurteilung der Stabilität, des Freibords und des Auftriebs in Übereinstimmung mit ISO 12217 (alle Teile) als wasserdicht oder witterungsbeständig angenommen werden. Wasserfahrzeuge, die den lokalen Entwurfsdrücken entsprechen, werden anschließend nach ISO 12215 5 geprüft.
ANMERKUNG Die Länge der Konstruktionswasserlinie ist in der „International Load Lines Convention 1966/2005“ der IMO festgelegt und kann bei Wasserfahrzeugen mit Überhang kleiner als LH sein. Diese Länge legt darüber hinaus bei 24 m die untere Grenze verschiedener IMO Konventionen fest.
Dieses Dokument gilt für Mehrrumpfboote, die aus denselben Werkstoffen wie in ISO 12215 5 gebaut sind und im intakten Zustand sind sowie einem der beiden folgenden Typen angehören:
- Sportboote, einschließlich Charter-Sportboote;
- gewerbliche Wasserfahrzeuge und Arbeitsboote.
Es ist nicht auf rein für professionelle Rennen ausgelegte Mehrrumpf Rennboote anwendbar.
Dieses Dokument ist anwendbar auf die Tragwerke von Fenstern, Bullaugen, Klappen, Seeschlagblenden und Türen.
Für die kompletten Dimensionierungen des Wasserfahrzeugs ist dieses Dokument für die Anwendung in Verbindung mit ISO 12215 8 für die Ruder, ISO 12215 9 für die Anhänge von Segelbooten und ISO 12215 10 für Takelagelasten und Takelagezubehör von Segelbooten vorgesehen. ISO 12215 6 kann für weitere Einzelheiten herangezogen werden.
In diesem Dokument, und sofern nicht anders festgelegt, sind die Abmessungen in (m), Flächen in (m2), Massen in (kg), Kräfte in (N), Momente in (Nm), Drücke in (kN/m2) (1 kN/m2 = 1 kPa), Spannungen und Elastizitätsmodule in (N/mm2) (1 N/mm2 = 1 MPa) angegeben.

Petits navires - Construction de la coque et échantillonnage - Partie 7: Détermination des charges des multicoques et de leur échantillonnage local en utilisant l'ISO 12215-5 (ISO 12215-7:2020)

Mala plovila - Konstrukcija trupa in dimenzioniranje - 7. del: Določanje obremenitev za večtrupna plovila in njihove krajevne dimenzije z uporabo ISO 12215-5 (ISO 12215-7:2020)

General Information

Status
Published
Public Enquiry End Date
05-Feb-2018
Publication Date
21-Jan-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
19-Nov-2020
Due Date
24-Jan-2021
Completion Date
22-Jan-2021

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SLOVENSKI STANDARD
SIST EN ISO 12215-7:2021
01-februar-2021
Mala plovila - Konstrukcija trupa in dimenzioniranje - 7. del: Določanje
obremenitev za večtrupna plovila in njihove krajevne dimenzije z uporabo ISO
12215-5 (ISO 12215-7:2020)

Small craft - Hull construction and scantlings - Part 7: Determination of loads for

multihulls and of their local scantlings using ISO 12215-5 (ISO 12215-7:2020)
Kleine Wasserfahrzeuge - Rumpfbauweise und Dimensionierung - Teil 7: Bestimmung
der Lasten für Mehrrumpffahrzeuge und ihrer lokalen Dimensionierungen unter
Anwendung der ISO 12215-5 (ISO 12215-7:2020)

Petits navires - Construction de la coque et échantillonnage - Partie 7: Détermination des

charges des multicoques et de leur échantillonnage local en utilisant l'ISO 12215-5 (ISO

12215-7:2020)
Ta slovenski standard je istoveten z: EN ISO 12215-7:2020
ICS:
47.020.10 Ladijski trupi in njihovi Hulls and their structure
konstrukcijski elementi elements
47.080 Čolni Small craft
SIST EN ISO 12215-7:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 12215-7:2021
---------------------- Page: 2 ----------------------
SIST EN ISO 12215-7:2021
EN ISO 12215-7
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2020
EUROPÄISCHE NORM
ICS 47.080
English Version
Small craft - Hull construction and scantlings - Part 7:
Determination of loads for multihulls and of their local
scantlings using ISO 12215-5 (ISO 12215-7:2020)

Petits navires - Construction de la coque et Kleine Wasserfahrzeuge - Rumpfbauweise und

échantillonnage - Partie 7: Détermination des charges Dimensionierung - Teil 7: Bestimmung der Lasten für

des multicoques et de leur échantillonnage local en Mehrrumpffahrzeuge und ihrer lokalen

utilisant l'ISO 12215-5 (ISO 12215-7:2020) Dimensionierungen unter Anwendung der ISO 12215-

5 (ISO 12215-7:2020)
This European Standard was approved by CEN on 20 July 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12215-7:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 12215-7:2021
EN ISO 12215-7:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 12215-7:2021
EN ISO 12215-7:2020 (E)
European foreword

This document (EN ISO 12215-7:2020) has been prepared by Technical Committee ISO/TC 188 "Small

craft" in collaboration with CCMC.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by May 2021, and conflicting national standards shall be

withdrawn at the latest by May 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 12215-7:2020 has been approved by CEN as EN ISO 12215-7:2020 without any

modification.
---------------------- Page: 5 ----------------------
SIST EN ISO 12215-7:2021
---------------------- Page: 6 ----------------------
SIST EN ISO 12215-7:2021
INTERNATIONAL ISO
STANDARD 12215-7
First edition
2020-11
Small craft — Hull construction and
scantlings —
Part 7:
Determination of loads for multihulls
and of their local scantlings using
ISO 12215-5
Petits navires — Construction de la coque et échantillonnage —
Partie 7: Détermination des charges des multicoques et de leur
échantillonnage local en utilisant l'ISO 12215-5
Reference number
ISO 12215-7:2020(E)
ISO 2020
---------------------- Page: 7 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Symbols .......................................................................................................................................................................................................................... 4

5 Application of this document .................................................................................................................................................................. 6

5.1 Materials ....................................................................................................................................................................................................... 6

5.2 Limitations .................................................................................................................................................................................................. 6

5.3 Overall procedure for the application of this document ..................................................................................... 7

6 Main dimensions, data and areas ........................................................................................................................................................ 7

6.1 Dimensions and data ......................................................................................................................................................................... 7

6.1.1 General...................................................................................................................................................................................... 7

6.1.2 Bottom deadrise of the hulls βx and chine beam B x of planing multihulls ................. 7

6.1.3 Wet deck bottom .............................................................................................................................................................. 8

6.1.4 Crossbeams ...................................................................... ..................................................................................................... 8

6.2 Areas .............................................................................................................................................................................................................11

7 Dimensions and pressure for panels and stiffeners under local loads ....................................................14

7.1 General ........................................................................................................................................................................................................14

7.2 Example of application on multihulls ...............................................................................................................................14

7.2.1 Sections .................................................................................................................................................................................14

7.2.2 Details on panel assessment and dimensions .....................................................................................16

7.2.3 The constant averaged pressure method ................................................................................................16

7.2.4 Other assessment and dimensioning methods ...................................................................................17

7.2.5 Panels acting as "natural" stiffeners ............................................................................................................17

7.3 Other topics on panel or stiffener dimensions .........................................................................................................17

8 Local pressure-adjusting factors ......................................................................................................................................................17

9 Local design pressures ................................................................................................................................................................................24

9.1 General ........................................................................................................................................................................................................24

9.2 Limits of areas ......................................................................................................................................................................................24

9.3 Tables defining the local design pressures for multihulls ..............................................................................24

9.4 Design pressure for trimaran floats P ...................................................................................................................27

TRFx

9.4.1 Pressure reduction factors ...................................................................................................................................27

9.4.2 Pressure ................................................................................................................................................................................27

9.5 Design pressure on watertight bulkheads and integral tanks ....................................................................27

10 Further treatment of structural elements subject to local loads ....................................................................27

11 Assessment of multihulls rudders, appendages and their wells .....................................................................28

12 Multihull global loads ...................................................................................................................................................................................28

12.1 General ........................................................................................................................................................................................................28

12.2 Typical structural arrangements ..........................................................................................................................................28

12.3 Global load assessment .................................................................................................................................................................30

12.3.1 General...................................................................................................................................................................................30

12.3.2 The simplified method .............................................................................................................................................30

12.3.3 The enhanced method ........................................................................................................................................... ...31

12.4 Design stresses under global loads ....................................................................................................................................32

12.5 Global load case GLC1: Diagonal load in quartering sea ..................................................................................32

12.6 Global load case GLC 2: Rig loads .........................................................................................................................................33

12.7 Combination of diagonal load GLC 1 and rig load GLC 2 for sailing multihulls ............................33

12.8 Global load case GLC 3: Asymmetric broaching loads in sailing multihulls ....................................33

© ISO 2020 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)

12.9 Global load case GLC 4: Longitudinal broaching/pitchpoling .....................................................................34

12.9.1 General...................................................................................................................................................................................34

12.9.2 Full method of analysis of the buoyancy load when the craft pitchpoles ....................35

12.10 Global load case GLC 5: Longitudinal force on one hull ....................................................................................36

12.10.1 General...................................................................................................................................................................................36

12.10.2 Longitudinal force ........................................................................................................................................................36

12.11 Global load case GLC 6: Bending of crossbeams connecting hulls for motor catamarans. .37

13 Structural arrangement for supporting global loads ..................................................................................................38

14 Multihulls used as commercial craft and workboats ...................................................................................................38

15 Information to be included in the owner's manual .......................................................................................................38

15.1 General ........................................................................................................................................................................................................38

15.2 Respect of maximum loaded displacement .................................................................................................................38

15.3 Operational guidance .....................................................................................................................................................................38

15.4 Information to take care of sandwich plating ...........................................................................................................38

15.5 Information required by Annex J of ISO 12215-5:2019 - for commercial craft and

workboat ...................................................................................................................................................................................................38

Annex A (informative) Application sheet of ISO 12215-7 ............................................................................................................39

Annex B (informative) "Established practice" recommendations for global loads

assessment using FEM methods and reporting .................................................................................................................41

Annex C (informative) "Established practice" details ......................................................................................................................43

Annex D (informative) Technical background and example of torsional moment analysis

with differential deflection of crossbeams ............................................................................................................................51

Bibliography .............................................................................................................................................................................................................................58

iv © ISO 2020 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(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 non-governmental, 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 by Technical Committee ISO/TC 188, Small craft.
A list of all parts in the ISO 12215 series can be found on the ISO website.

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.
© ISO 2020 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)
Introduction

The reason underlying the preparation of this document is that standards and recommended

practices for loads on the hull and the dimensioning of small craft differ considerably, thus limiting the

general worldwide acceptability of boat scantlings. This document has been set towards the minimal

requirements of the current practice.

The dimensioning according to this document is regarded as reflecting current practice, provided

the craft is correctly handled in the sense of good seamanship and operated at a speed appropriate

to the prevailing sea state in a safe and responsible manner, having due cognisance of the prevailing

conditions.

Implementation of this document allows to achieve an overall structural strength that ensures the

watertight and weathertight integrity of the craft. This document is intended to be a tool to determine

the scantlings of a craft as per minimal requirements. It is not intended to be a structural design

procedure.

The mechanical property data supplied as default values in this document make no explicit allowance

for deterioration in service nor provide any guarantee that these values can be obtained for any

particular craft.

Like the other parts of ISO 12215, this document was developed to assess the structure of recreational

craft up to 24 m L , but it can also be used, where relevant, for non-recreational craft, workboats or

yachts with an IMO load line length of up to 24 m, with the necessary critical mind.

vi © ISO 2020 – All rights reserved
---------------------- Page: 12 ----------------------
SIST EN ISO 12215-7:2021
INTERNATIONAL STANDARD ISO 12215-7:2020(E)
Small craft — Hull construction and scantlings —
Part 7:
Determination of loads for multihulls and of their local
scantlings using ISO 12215-5
1 Scope

This document defines the dimensions, local design pressures and global loads acting on multihull

craft with a hull length (L ) or load line length of up to 24 m (see Note). It considers all parts of the

craft that are assumed watertight or weathertight when assessing stability, freeboard and buoyancy in

accordance with ISO 12217 (all parts). Scantlings corresponding to the local design pressures are then

assessed using ISO 12215-5.

NOTE The load line length is defined in the OMI "International Load Lines Convention 1966/2005", it can

be smaller than L for craft with overhangs. This length also sets up at 24 m the lower limit of several IMO

conventions.

This document is applicable to multihulls built from the same materials as in ISO 12215-5, in intact

condition, and of the two following types:
— recreational craft, including recreational charter vessels;
— commercial craft and workboats.

It is not applicable to multihull racing craft designed only for professional racing.

This document is applicable to the structures supporting windows, portlights, hatches, deadlights

and doors.

For the complete scantlings of the craft, this document is intended to be used in conjunction with

ISO 12215-8 for rudders, ISO 12215-9 for appendages of sailing craft and ISO 12215-10 for rig loads and

rig attachment in sailing craft. ISO 12215-6 can be used for additional details.

Throughout this document, unless otherwise specified, dimensions are in (m), areas in (m ), masses

2 2

in (kg), forces in (N), moments in (Nm), Pressures in (kN/m ) (1 kN/m = 1 kPa), stresses and elastic

2 2
modulus in (N/mm ) (1 N/mm = 1 MPa).
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 8666:2020, Small craft — Principal data

ISO 12215-5:2019, Small craft — Hull construction and scantlings — Part 5: Design pressures for monohulls,

design stress, scantlings determination

ISO 12215-8:2009, Small craft — Hull construction and scantlings — Part 8: Rudders

ISO 12215-9:2012, Small craft — Hull construction and scantlings — Part 9: Sailing craft appendages

ISO 12215-10:2020, Small craft — Hull construction and scantlings — Part 10: Rig loads and rig

attachments in sailing craft
© ISO 2020 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)

ISO 12217-1:2015, Small craft — Stability and buoyancy assessment and categorization — Part 1: Non-

sailing boats of hull length greater than or equal to 6 m

ISO 12217-2:2015, Small craft — Stability and buoyancy assessment and categorization — Part 2: Sailing

boats of hull length greater than or equal to 6 m

ISO 12217-3:2015, Small craft — Stability and buoyancy assessment and categorization — Part 3: Boats of

hull length less than 6 m
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
multihull

craft with two or more hulls with a connecting wet deck (3.8)/crossbeams above the loaded waterline,

as opposed to a tunnel boat or scow

Note 1 to entry: See Clause 6 and Figure 2 for the main dimensions of a multihull.

3.2
design categories

description of the sea and wind conditions for which a craft is assessed to be suitable

Note 1 to entry: The design categories are defined in ISO 12217 (all parts).

Note 2 to entry: The definitions of the design categories are in line with the European Recreational Craft Directive

2013/53/EU.
[SOURCE: ISO 12215-5:2019, 3.1.]
3.3
loaded displacement
LDC

mass of water displaced by the craft, including all appendages, when in fully loaded ready for use

condition

Note 1 to entry: The fully loaded ready for use condition is further defined in ISO 8666.

[SOURCE: ISO 12215-5:2019, 3.2.]
3.4
mass in minimum operating conditions
mass of the craft in minimum operating condition
Note 1 to entry: The minimum operating condition is further defined in ISO 8666.
3.5
sailing craft
craft for which the primary means of propulsion is wind power
Note 1 to entry: It is further defined in ISO 8666.

Note 2 to entry: In this document, non-sailing craft are considered as motor craft.

2 © ISO 2020 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 12215-7:2021
ISO 12215-7:2020(E)
[SOURCE: ISO 12215-5:2019, 3.3.]
3.6
beam of hull
beam across the outer hulls
Note 1 to entry: The measurement of the beam of hulls is specified in ISO 8666.
3.7
chine beam
beam at chine of planing hulls
Note 1 to entry: It is further characterized in 6.1.2.
3.8
wet deck

underside area of the structure connecting hulls with an area greater than 5 % L B

H H

Note 1 to entry: Some multihulls (3.1) have no wet deck but just crossbeams. i.e. connecting beams.

3.9
craft speed

for motor craft, maximum speed in calm water and m condition that is declared by the manufacturer,

LDC
expressed in knots
[SOURCE: ISO 12215-5:2019, 3.6.]
3.10
displacement craft
motor craft whose speed is such that VL<5
[SOURCE: ISO 12215-5:2019, 3.7, modified - the definition is reworded.]
3.11
displacement mode

mode of running of a motor craft in the sea such that its mass is mainly supported by buoyancy forces

Note 1 to entry: This is the case where the actual speed in a seaway in m condition is such that its speed/

LDC
length ratio makes the craft behave as a displacement craft (3.10).

[SOURCE: ISO 12215-5:2019, 3.8, modified - in the definition, "craft" is replaced with "motor craft".]

3.12
planing craft
motor craft whose speed is such that VL≥5

Note 1 to entry: This speed/length ratio limit has been arbitrarily set up in this document, but it can vary from

one craft to another according to hull shape and other parameters.
[SOURCE: ISO 12215-5:2019, 3.9, modified - the definition is reworded.]
3.13
planing mode
mode of running of a motor craft in the sea such that a significa
...

SLOVENSKI STANDARD
oSIST prEN ISO 12215-7:2018
01-februar-2018
0DODSORYLOD.RQVWUXNFLMDWUXSDLQ]DKWHYDQHODVWQRVWLGHO8JRWDYOMDQMH
ODVWQRVWLYHþWUXSQLKSORYLO ,62',6

Small craft - Hull construction and scantlings - Part 7: Scantlings determination of

multihulls (ISO/DIS 12215-7 :2017)

Petits navires - Construction de coques et échantillonnage - Partie 7: Multicoques

(ISO/DIS 12215-7:2017)
Ta slovenski standard je istoveten z: prEN ISO 12215-7
ICS:
47.020.10 Ladijski trupi in njihovi Hulls and their structure
konstrukcijski elementi elements
47.080 ýROQL Small craft
oSIST prEN ISO 12215-7:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 12215-7:2018
---------------------- Page: 2 ----------------------
oSIST prEN ISO 12215-7:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 12215-7
ISO/TC 188 Secretariat: SIS
Voting begins on: Voting terminates on:
2017-11-14 2018-02-06
Small craft — Hull construction and scantlings —
Part 7:
Scantlings determination of multihulls
Petits navires — Construction de coques et échantillonnage —
Partie 7: Multicoques
ICS: 47.080
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
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ISO/DIS 12215-7:2017(E)
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oSIST prEN ISO 12215-7:2018
ISO/DIS 12215-7:2017(E)
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ii © ISO 2017 – All rights reserved
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
Contents

Foreword .......................................................................................................................................................................... v

Introduction.................................................................................................................................................................... vi

1 Scope .................................................................................................................................................................... 1

2 Normative references .................................................................................................................................... 1

3 Terms and definitions.................................................................................................................................... 2

4 Symbols ............................................................................................................................................................... 4

5 Application of ISO 12215-7 .......................................................................................................................... 6

5.1 General ................................................................................................................................................................ 6

6 Main dimensions, data and areas .............................................................................................................. 7

6.1 Dimensions of the platform ......................................................................................................................... 7

6.2 Areas ................................................................................................................................................................. 10

7 Dimensions and pressure for panels and stiffeners under local loads ..................................... 11

7.1 General ............................................................................................................................................................. 11

7.2 Example of application on multihulls ................................................................................................... 12

7.3 Other topics on panel or stiffener dimensions .................................................................................. 15

8 Local pressure adjusting factors ............................................................................................................. 15

8.1 General requirements ................................................................................................................................ 15

9 Local design pressures for multihulls ................................................................................................... 19

9.1 General ............................................................................................................................................................. 19

9.2 Limits of application .................................................................................................................................... 19

9.3 Tables defining the local design pressures for multihulls ............................................................ 19

9.4 Design pressure for trimaran floats P ............................................................................................. 22

TRF

9.5 Design pressure on watertight bulkheads and integral tanks ..................................................... 22

10 Further treatment of structural elements subject to local loads ................................................ 22

11 Assessment of multihulls rudder and appendages .......................................................................... 23

12 Global loads .................................................................................................................................................... 23

12.1 General ............................................................................................................................................................. 23

12.2 Most frequent structural arrangements .............................................................................................. 23

12.3 Global loads to be checked ........................................................................................................................ 24

12.4 Design stresses under global loads ........................................................................................................ 26

12.5 Global load case 1: Diagonal load in quartering sea ........................................................................ 27

12.6 Global load case 2: Rig loads..................................................................................................................... 27

12.7 Combination of diagonal load LC1 and rig load LC2 for sailing multihulls ............................. 28

12.8 Global load case 3: Asymmetric broaching of sailing multihulls ................................................ 28

12.9 Global load case 4: Longitudinal broaching / pitchpoling ............................................................. 28

12.10 Global load case 5: Longitudinal force/shock on one hull ............................................................. 30

12.11 Global load case LC 6: Bending moment on beams connecting hulls for non-sailing

catamarans. .................................................................................................................................................... 31

13 Structural arrangement for global loads ............................................................................................. 32

14 Multihulls used as workboats .................................................................................................................. 32

15 Information to be included in the owner's manual.......................................................................... 32

15.1 General ............................................................................................................................................................. 32

15.2 Respect of maximum loaded displacement ........................................................................................ 32

15.3 Operational guidance .................................................................................................................................. 33

15.4 Possibility of outer skin damage ............................................................................................................. 33

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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017

15.5 Usage as a workboat .................................................................................................................................... 33

Annex A (normative) Application declaration of ISO 12215-7 ................................................................. 34

Annex B (informative) "Established practice" Tables and calculation for global loads

assessment ...................................................................................................................................................... 35

Annex C (informative) "Established practice" details .................................................................................. 37

Annex D (informative) Technical background and example of torsional moment analysis

with differential deflection of crossbeams ......................................................................................... 44

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2013/53/EU aimed to be covered ..................................................... 51

Bibliography ...................................................................................................................................................... 53

iv © ISO 2017 – All rights reserved
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
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 non-governmental, 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 on 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 the following URL:
www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 188, Small craft, together with CEN/BT/WG 69,

Small craft.
A list of all parts in the ISO 12215 series can be found on the ISO website.
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
Introduction

The reason underlying the preparation of this part of ISO 12215 is that standards and recommended

practices for loads on the hull and the dimensioning of small craft differ considerably from one to another,

thus limiting the general worldwide acceptability of boat scantlings. This part of ISO 12215 has been set

towards the lower boundary of the range of current practice.

The objective of this part of ISO 12215 is to achieve an overall structural strength that ensures the

watertight and weathertight integrity of the craft. It is intended to be a tool to assess the scantlings of a

craft against lower bound practice and it is not intended to be a structural design procedure.

The assessment shall generally include all parts of the craft that are assumed watertight or weathertight

when assessing stability, freeboard and buoyancy in accordance with ISO 12217 and are essential to the

safety of the craft and of persons on board.

For the complete scantlings of the craft, this part of ISO 12215 shall be used in conjunction with Part 5

for final scantlings determination, Part 6, for details, Part 8 for rudders and Part 9 for appendages and

Part 10 for rig loads and rig attachment.

The mechanical property data supplied as default values in Part 5 make no explicit allowance for

deterioration in service nor provide any guarantee that these values can be obtained for any particular

craft. The responsibility for the decision to use this part of ISO 12215 as part of the design procedure

rests solely with the designer and/or manufacturer.

The design pressures given in this part of ISO 12215 shall only be used with the given methods, equations

and safety factors.

The dimensioning according to this part of ISO 12215 is regarded as reflecting current practice, provided

the craft is correctly handled in the sense of good seamanship and operated at a speed appropriate to the

prevailing sea state and operated in a safe and responsible manner, having due cognisance of the

prevailing conditions. It may not be suitable for performance racing craft and excludes boats designed

only for professional racing.

This document is not a design standard and designers/builders are strongly cautioned from attempting

to design craft such that nearly all structural components only just comply.

The scantling determination of windows, portlights, deadlights, hatches and doors shall be assessed using

either ISO 12216 which is a simplified scantlings standard, or using the pressures determined in this part

of ISO 12215, and/or ISO/DIS 12215-5, particularly for panels other that non stiffened plates, then using

the equations, safety factors, mechanical properties and detailed requirements of ISO 12216.

Important notice:

a) ISO/TC 188/WG 18 believes that this part of ISO 12215 is the best that can be achieved at the time

of publication. It has therefore decided to publish this document as a DIS. It is anticipated that wider

usage may reveal a number of issues that require modification.

b) In addition, this part of ISO 12215 needs to be applied with a critical mind, and users are invited to

report to WG 18, TC secretariat, or national standardization body, for any items that are considered

to require correction, together with supporting evidence, be that theoretical or based on

satisfactory, long-term service experience with actual boats operating in the appropriate design

category sea states.
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017

Like the other parts of this International standard, this document was developed to assess the structure

of recreational craft up to 24 m L , but it may also be used, where relevant, for non-recreational craft,

workboats or yachts of greater length and L up to 30/32 m or 24 m Load line length, with the necessary

critical mind.
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oSIST prEN ISO 12215-7:2018
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
Small craft — Hull construction and scantlings — Part 7:
Scantlings determination of multihulls
1 Scope

This part of ISO 12215 applies to the determination of local design pressures, and to the determination

of the global loads acting on connected structural members of multihull craft constructed from fibre-

reinforced plastics, aluminium or steel alloys, glued wood or other suitable boat building material with a

hull length L up to and including 24m according to ISO 8666.

It only applies to craft in the intact condition and with a maximum speed ≤ 50 knots in m conditions.

LDC

It is not applicable to Hydrofoils, Small Waterplane Area Twin-Hull Ships (SWATHS) or surface effect

multihulls.

The assessment shall generally include all structural parts of the craft that are assumed watertight or

weathertight when assessing stability, freeboard and buoyancy according to ISO 12217 and are essential

to the safety of the craft and of persons on board.

For the complete scantlings of the craft, this part of ISO 12215 shall be used in conjunction with Part 5

for detail local scantlings; Part 6, for construction details, Part 8 for rudders and Part 9 for appendages,

and Part 10 for rig loads and rig attachment, with eventual changes coming from this document.

The scantling determination of windows, portlights, deadlights, hatches and doors shall be assessed using

either ISO 12216 which is a simplified scantlings standard, or using the pressures determined in this

document and/or ISO/DIS 12215-5, particularly for panels other that non stiffened plates and their

supporting structures, then using the equations, safety factors, mechanical properties and detailed

requirements of ISO 12216.

The scope of ISO 12215 was initially developed for up to 24 m hull length L , but it may be applied for

craft up to 24 m load line length and beyond, (see Note) with the necessary critical mind.

Scantlings derived from this document are primarily intended to apply to recreational craft including

recreational charter vessels. They are considered to correspond to the minimum strength requirements

of motor and sailing craft which are operated in a safe and responsible manner, having due cognisance of

the prevailing conditions. It primarily applies to boats designed to be available to open public, and used

by non-professional crews, it is not suitable to racing craft that are only performance oriented and

excludes boats designed only for professional racing. However Clause 14 considers the usage of a

multihull as a workboats, with professional crew, provided Annex I of ISO/DIS 12215-5 is complied with.

Throughout this document, and unless otherwise specified, dimensions are in (m), Areas in (m²), masses

in kg, forces in (N), moments in (Nm), Pressures in kN/m² (1kN/m²=1 kPa), stresses and elastic modulus

in N/mm² (1N/mm²=1 Mpa).

NOTE The load line length is defined in the OMI "International Load Lines Convention 1966/2005", it

may be larger than LH for craft with overhangs. This length also sets up, at 24 m, the lower limit of

several IMO conventions.
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.

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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
ISO 8666, Small craft — Principal data

ISO/DIS 12215-5, Small craf — Hull construction and scantlings Part 5: Design pressures for monohulls,

design stress, scantlings determination

ISO 12215-6, Small craft — Hull construction and scantlings Part 6: Construction details

ISO 12215-8, Small craft — Hull construction and scantlings Part 8: Rudders

ISO 12215-9, Small craft — Hull construction and scantlings Part 9: Sailing craft- Appendages

ISO/DIS 12215-10, Small craft — Hull construction and scantlings Part 10: Rig loads and rig attachments

ISO 12217-1, Small craft — Stability and buoyancy assessment and categorization — Part 1: Non sailing

boats of hull length greater than or equal to 6 m

ISO 12217-2, Small craft — Stability and buoyancy assessment and categorization — Part 2: Sailing boats

of hull length greater than or equal to 6 m
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
[Definition 3.3 to 3.7 SOURCE: ISO 8666: 2016]
3.1
multihull

craft with two or more hulls with a connecting wet deck/platform or beams above the loaded waterline,

as opposed to a tunnel boat or scow

Note 1 to entry: Clause 6 and Figure 1 gives information on main dimensions of a multihull.

3.2
design categories

description of the sea and wind conditions for which a boat is assessed to be suitable

Note 1 to entry: the characteristics for the different design categories are in line with the European Recreational

Craft Directive 2013/53/EU.
3.3
loaded displacement mass
LDC

mass of the craft, including all appendages, when in the fully loaded ready for use condition as defined in

ISO 8666

Note 1 to entry: this displacement includes all possible options like generator, air conditioning, etc.

Note 2 to entry: it is important that this value is not surpassed, see 5.1.
3.4
mass in Minimum operating conditions
mass of the craft in minimum operating condition as defined in ISO 8666
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
3.5
sailing craft

craft for which the primary means of propulsion is wind power, as defined in ISO 8666

Note 1 to entry: In ISO 12215, non-sailing craft are considered as motor craft.
3.6
beam of hull
beam across the outer hulls, as defined in ISO 8666
3.7
beam waterline

sum of the waterline beams of all hulls, boat upright and in loaded displacement condition, according to

ISO 8666
3.8
wet deck

underside area of the structure connecting hulls with an area greater than 5 % L B

H H
Note 1 to entry: Some multihulls have no wet deck but just crossbeams.
3.9
boat speed

for motor craft , in knots, is, the maximum speed in calm water declared by the manufacturer, with the

craft in conditions. For sailing craft, speed does not need to be declared
LDC
3.10
non walking areas

 either the areas defined in the owner's manual as both outside of the working deck and where people

are not liable to stand or walk in normal or emergency operation, or

 areas of the working deck of a multihull with an inclination of more than 25against the horizontal

in the longitudinal and transverse directions
All other areas of the deck and superstructures are deemed walking areas.
3.11
displacement craft

powered craft whose maximum speed in flat water and m conditions, declared by its manufacturer, is

LDC
 5
such that
3.12
displacement mode

mode of running of a craft in the sea such that its mass is mainly supported by buoyancy forces

Note 1 to entry: This is the case where actual the speed/length ratio in a seaway makes the craft behave as a

displacement craft, in conditions.
LDC
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
3.13
planing craft

powered craft whose maximum speed in flat water and m conditions, declared by its manufacturer, is

LDC
such that
 5

Note 1 to entry: This speed/length ratio limit has been arbitrarily set up for the purpose of this part of ISO 12215

and to ensure that the craft is well in planing but it in reality the planing mode speed may vary from one boat to

another according to hull shape and other parameters.
3.14
planing mode

mode of running of a craft in the sea such that a significantly part of its mass is supported by forces coming

from dynamic lift due to speed in the water
4 Symbols

Unless specifically otherwise defined, the symbols shown in Table 1 are used in this part of ISO 12215.

Table 1 —Symbols, dimensions, coefficients, parameters
Reference/
Symbol Unit Designation/Meaning of symbol Clause
concerned
General dimensions and data
m² Total sail area as defined in 3.5 3.5
Beam between centres of buoyancy 6.1 & Fig 1
m Beam between upper shrouds chainplates Annex B

m Beam at the outside of wet deck/beam connection with hulls at section x 6.1 & Fig 1

m Beam of waterline according to ISO 8666 6.1 & Fig 1

m Beam at the inside of wet deck/beam connection with hulls at section x 6.1 & Fig 1

BWDx
m Beam of hull according to 3.7 6.1 & Fig 1
m Beam of hull at overhang root Table 11, Fig7
m Depth of hull at overhang root Table 11, Fig7
m Length of crossbeam i Table 11, Fig7
m Length between main beams centre of inertia Annex B & C
m Length of hull according to ISO 8666 1
m Length of overhang (forward or aft) on float i Table 11, Fig7
OHi
m Length of waterline according to ISO 8666 Fig 1
m Length of the wet deck measured parallel to LWL Fig 1
kg Mass of displacement in fully loaded condition according to ISO 8666 3.3, 9
LDC
kg Mass in minimum operating condition according to ISO 8666 3.4, 11
m Max canoe body depth (see Figure 1) Fig 1, 9.3
C i
V Knots Boat maximum speed in fully loaded condition (m ) Table 5.2,
LDC
Knots Apparent wind speed in knots Annex B & C
AWK
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oSIST prEN ISO 12215-7:2018
ISO 12215-7:2017
Reference/
Symbol Unit Designation/Meaning of symbol Clause
concerned
Panels , stiffeners and local dimensions and data
m² Panel or stiffener supported area Table 5.9
b mm Short unsupported dimension of panel plating Table 5.9
l mm Long unsupported dimension of panel plating Table 5.9
s mm Stiffener spacing (small unsupported dimension of stiffener) Table 5.9

l mm Stiffener length: long unsupported dimension of stiffener (frame/stringer) Table 5.9

Point at section x where the pressure is assessed Figures 1,2
m Local canoe body depth at section x (see Figure 1) Fig 1
x i
x m Distance of a section x from aft of L Fig 1, 9.3
m Distance of a section x from aft of LWD Fig 1, 9.3
Height of point Q above WL at section x
Qx m Fig 1, 9.3
m Height of local canoe body above W at section x (usually <0) Fig 1, 9.3
T x
m Height of local hard chine above WL at section x for planing craft Fig 1, 9.3
m Height above WL of the theoretical side/deck limit at section x Fig 1, 9.3
SDTM x
m Height above WL of the actual side/deck limit at section x Fig 1, 9.3
SDM x
Z Fig 1, 9.3
m Height above WL of the theoretical wet deck height at section x
WDTx
m Height above W of the actual height of wet deck at section x Fig 1, 9.3
WDx L
 ,
Degree Longitudinal and transverse angle of superstructure Fig 1, Table5
LS TS
 ,
Degree Longitudinal angle of wet deck/crossbeam front Fig 1, Table5
Fig 1, 9.3
Degree Deadrise at section x, not to be taken <30° nor > 60°
Calculation data, coefficients, etc.
1 Area pressure distribution factor Table 5,it 9
1 Wet deck transverse pressure distribution factor Table 5,it 15
BWD
1 Design category factor Table 5,it1
1 Deadrise pressure reduction factor for multihulls Table 5,it 8
g’s Dynamic load factor for multihulls Table 5,it2
DYNM
1 Wet deck front angle factor
Table 5,it 11
FWD
1 Deck longitudinal pressure distribution factor for multihulls
LDM Table 5,Fig4
1 Side longitudinal pressure distribution factor for multihulls Table 5,Fig3
1 Wet deck longitudinal pressure distribution factor Table 5,Fig5
LWD

1 Superstructure/deckhouse pressure distribution factor for Multihulls Table 5,it 10

SUP
1 Wet deck vertical pressure correction factor Table 5,Fig6
ZWD
Design pressures for sailing and displacement power multihulls
P 2

BMU BASE kN/m Base bottom/side pressure for catamaran hulls and trimaran central hull Table 6

kN/m Design bottom/side pressure at section x and at CL of hulls Table 6
BMUx
Base
...

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