FprEN ISO 12215-9

SLOVENSKI STANDARD
01-oktober-2024
Mala plovila - Konstrukcija trupa in zahtevane lastnosti - 9. del: Dodatni pribor
jadrnic (ISO/DIS 12215-9:2024)
Small craft - Hull construction and scantlings - Part 9: Sailing craft appendages (ISO/DIS
12215-9:2024)
Kleine Wasserfahrzeuge -Rumpfbauweise und Dimensionierung– Teil9: Anhänge von
Segelbooten (ISO/DIS 12215-9:2024)
Petits navires - Construction de coques et échantillons - Partie 9: Appendices des
bateaux à voiles (ISO/DIS 12215-9:2024)
Ta slovenski standard je istoveten z: prEN ISO 12215-9
ICS:
47.020.10 Ladijski trupi in njihovi Hulls and their structure
konstrukcijski elementi elements
47.080 Čolni Small craft
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 12215-9
ISO/TC 188
Small craft — Hull construction and
Secretariat: SIS
scantlings —
Voting begins on:
Part 9: 2024-08-01
Sailing craft appendages
Voting terminates on:
2024-10-24
Petits navires — Construction de coques et échantillonnage —
Partie 9: Appendices des bateaux à voiles
ICS: 47.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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Reference number
ISO/DIS 12215-9:2024(en)
DRAFT
ISO/DIS 12215-9:2024(en)
International
Standard
ISO/DIS 12215-9
ISO/TC 188
Small craft — Hull construction and
Secretariat: SIS
scantlings —
Voting begins on:
Part 9:
Sailing craft appendages
Voting terminates on:
Petits navires — Construction de coques et échantillonnage —
Partie 9: Appendices des bateaux à voiles
ICS: 47.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
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Published in Switzerland Reference number
ISO/DIS 12215-9:2024(en)
ii
ISO/DIS 12215-9:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Design stresses . 3
6 Structural components to be assessed . 5
7 Load cases . 5
7.1 General .5
7.1.1 Status of design load cases .5
7.1.2 Limitation of load cases .6
7.2 Load case 1 — Fixed keel at 90° knockdown .6
7.3 Load case 2 — Canted keel steady load at 30° heel with dynamic overload factor .7
7.3.1 General .7
7.3.2 Specific requirements for canting keel structure .8
7.4 Load case 3 — Keelboat vertical pounding .8
7.5 Load case 4 — Keelboat longitudinal impact .9
7.5.1 Value of longitudinal impact and bending moment . .9
7.6 Load case 5 — Centreboard on capsize recoverable dinghies .10
7.7 Load case 6 — Centreboard or dagger board upwind .10
7.7.1 Non-ballasted centreboards .10
7.7.2 Ballasted centreboards .11
7.8 Other load cases .11
7.8.1 General .11
7.8.2 Combined bending and torsion (knockdown case) .11
7.8.3 Combined bending moment and vertical load (load case 3) . 13
7.8.4 Other combined load cases. 13
8 Computational methods .13
8.1 General . 13
8.2 General guidance for assessment by 3D numerical procedures .14
8.2.1 3D numerical procedures .14
8.2.2 Material properties .14
8.2.3 Boundary assumptions .14
8.2.4 Load application . .14
8.2.5 Model idealization .14
8.3 Assessment by strength of materials/non-computational-based methods .14
9 Compliance .15
Annex A (normative) Application declaration .16
Annex B (informative) Information on metal for appendages and fasteners and established
practice for fastening and welding . 17
Annex C (informative) Established practice structural arrangement for ballast keels .25
Annex D (informative) Established practice calculation of keel fin strength (fixed, lifting or
canting) and fixed ballast keel connected by bolts .38
Annex E (informative) Geometrical properties of some typical appendage aerofoil section
shapes .55
Annex F (informative) Simplified fatigue strength assessment .58

iii
ISO/DIS 12215-9:2024(en)
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2013/53/EU aimed to be covered.69
Bibliography .71

iv
ISO/DIS 12215-9:2024(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 464, Small Craft, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 12215-9:2012), which has been technically
revised.
The main changes are as follows:
— Editorial changes throughout to improve format, language, consistency, clarity, interpretation,
readability, acknowledgement of current practice and compliance with this part of the standard
— The addition of consideration of canting keel actuator and keel support structure to Table 3
— Compliance: Annex A shall be completed in all instances. Wording has been clarified.
— The addition of qualified backing plate diameter and thickness treatment in the case of reduced hull
thickness in Table D.2
— A specific caution about bolt proximity to welds in Clause D.4.7
— Re-assessment of Annex F Simplified fatigue strength assessment, doubling the operational life to 16
million stress cycles and associated MSF calculation
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.

v
ISO/DIS 12215-9:2024(en)
Introduction
This document recognises the importance of adequate scantlings, construction practice and condition
assessment for sailing craft appendages, principally the ballast keel.
The loss of a ballast keel leading to craft capsize is one of the major casualty hazards on sailing craft
and therefore the structural effectiveness of all elements of the keel and its connection to the craft is
paramount.
This document specifies the design loads and their associated stress factors. The user (e,g, the designer or
builder) then has a choice of two options to assess the structural arrangement:
a) Use of computational methods which allow the structure to be modelled three-dimensionally. Methods
include finite element analysis, matrix displacement or framework methods, following which Annex A
shall be completed for compliance. General guidance is provided on modelling assumptions within
Clause 8 of this document.
or
b) Use of simplified two-dimensional stress formulae. These are presented in Annexes B to F and, if this
option is chosen, use of all applicable Annexes will be necessary to fulfil the requirements of this
document, following which Annex A shall be completed for compliance.
This document has been developed in consideration of current practice and sound engineering principles.
The design loads and criteria of this document may be used with the scantling determination formulae of
this document or using equivalent engineering methods as indicated in a) above.
This document reflects current practice, provided the craft is correctly handled in accordance with good
1)
seamanship, is well designed and built , maintained, equipped and operated at a speed appropriate to the
prevailing sea state. Inspection of all appendages after grounding is essential.
Racing craft are not the principal focus of ISO 12215. In particular, users are strongly cautioned against
attempting to design scantlings for racing craft such that scantlings only just comply.
Annex J of ISO 12215-5:2019 provides additional requirements for commercial craft and workboats. The
principles of these requirements may also be considered applicable to craft that engage in racing, where
their usage conditions warrant an independent maintenance and survey program set up by a qualified
organization. This is further discussed in Clause 9 of this document.
1) Compliance with this document will not ensure a satisfactory design in all cases nor absolve the user, such as the
designer or builder, of their design responsibilities, with whom such responsibilities are entirely vested.

vi
DRAFT International Standard ISO/DIS 12215-9:2024(en)
Small craft — Hull construction and scantlings —
Part 9:
Sailing craft appendages
1 Scope
This document defines the loads and specifies the scantlings of sailing craft appendages on monohull sailing
craft with a length of hull (L ) measured according to ISO 8666 or a load line length (see NOTE 1 in Clause 1
H
of ISO 12215-5) of up to 24 m. It gives:
— design stresses,
— the structural components to be assessed,
— load cases and design loads for keel, centreboard and their attachments,
— computational methods and modelling guidance, and
— the means for compliance with its provisions.
2 Normative references
The following referenced documents are indispensable for the application 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. Dated versions are intended where this part makes direct
reference to a section in that dated part of ISO 12215.
ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and
studs with specified property classes — Coarse thread and fine pitch thread
ISO 3506-1, Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners — Part 1: Bolts,
screws and studs with specified grades and property classes
ISO 8666, Small craft — Principal data
ISO 12215-3, Small craft — Hull construction and scantlings — Part 3: Materials: Steel, aluminium alloys, wood,
other materials
ISO 12215-5:2019, Small craft — Hull construction and scantlings — Part 5: Design pressures for monohulls,
design stresses, scantlings determination
ISO 12215-6:2008, Small craft — Hull construction and scantlings — Part 6: Structural arrangements and details
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.
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

ISO/DIS 12215-9:2024(en)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
design category
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 design categories are in line with the European Recreational Craft Directive
2013/53/EU.
3.2
loaded displacement
m
LDC
mass of 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.
3.3
sailing craft
craft for which the primary means of propulsion is wind power
Note 1 to entry: It is further defined in ISO 8666.
3.4
mass of keel
m
KEEL
mass of the ballast keel, i.e. keel fin plus bulb, where fitted, and, for twin or multiple keels, of a single keel
Note 1 to entry: The mass of keel is expressed in kg.
4 Symbols
For the purposes of this document, unless specifically otherwise defined, the symbols given in Table 1 apply.
Table 1 — Nomenclature
Symbol Unit Designation/meaning of symbol Ref/Subclause
A m Area of fully deployed centreboard 7.7.1
CB
Reference sail area (mainsail + fore triangle + wing mast) as per
A m 7.7.1
S
ISO 12217-2
Distance along keel centreline, from centre of gravity (CG) of keel to
a m 7.2
keel junction with hull or tuck
b mm Overall breadth of the appendage aerofoil section E.1
f
c m Distance along keel centreline from keel junction to floor mid-height 7.2
c m Average value of c for several floors 7.5.1
a
e m Proportion of the total side force taken by the centreboard 7.7.1
F N Design force with i according to load case 7
i
2 2
g m/s Acceleration of gravity = 9,81 m/s 7
h m Height of centre of area of A 7.7.1
CE S
h m Height of keel between its bottom and hull connection 7.5.1
K
h
m Height of application of force F (load case 4) 7.5.1
F4 4
I cm Longitudinal second moment appendage aerofoil section E.2.2
L
k – Design category coefficient 5, Table 2
DC
k – Appendage section shape factor Table E.1
f
ISO/DIS 12215-9:2024(en)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Unit Designation/meaning of symbol Ref/Subclause
k – Appendage section shape factor Table E.1
f1
k – Load case coefficient 5, Table 3
LC
k – Length displacement coefficient 7.7.1
LD
k – Material coefficient 5, Table 2
MAT
L mm Chord length of appendage aerofoil section E.1
f
L m Length of waterline in m conditions 7.7.1
WL LDC
m kg See definition 3.2 3.2, 7
LDC
m kg See definition 3.4 3.4, 7.4
KEEL
M
N·m Design bending moment, with index I and J according to load case 7
IJ
SM cm Appendage aerofoil shape longitudinal section modulus E.2.2
L
st N/mm Stress, which can be σ or τ , and where i can be LIM, d, u, y, yw or yu 5
i
t mm Wall thickness of hollow appendage aerofoil section E.1
f
α deg. Angle of attack of centreboard 7.7.1
ε % Elongation at break Table B.2
R
θ deg. Angle between keel axis and centreline for canting keels 7.3.1
5 Design stresses
The maximum stress shall be calculated for each relevant structural component and load case.
The design stress, st , is the relevant limit stress multiplied by various stress coefficients:
d
st =×st kk××k in N / mm (1)
d LIMMAT LC DC
where
st
is the limit stress, with st representing either σ, the direct stress, or τ, the shear stress, and index
LIM
LIM is as follows:
— for metal in the unwelded state or well clear of the heat affected zone (HAZ),
min(st ;0,5×)st where index y is the yield strength and index u is the ultimate strength, i.e.
yu
σσ, for direct stress, ττ, for shear stress and σσ, for bearing stress;
yu yu by bu
— for metal within the HAZ, min(st ;0,5×)st where index y is the yield strength and index u
yw uw
is the ultimate strength, i.e. σσ, , for direct stress, ττ, for shear stress and for
yw uw yw uw
σσ, bearing stress;
bywbuw
— for wood and fibre-reinforced polymer (FRP), the ultimate strength in tensile σ ,
tu
compressive σ , flexural σ , bearing, σ or shear stress τ ;
cu fu bu u
k
is the material coefficient as defined in Table 2, with the design stress adjusted according to the
MAT
material;
k
is the load case coefficient as defined in Table 3, with the design stress adjusted according to the
LC
load case;
k
is the design category coefficient as defined in Table 2, with allowance for an increase in design
DC
stress for lower design categories.
Table 2 gives details on these variables.

ISO/DIS 12215-9:2024(en)
The values of st — i.e. σσ,,τ for unwelded metals, σσ,,ττ, for welded metals in a HAZ,
LIM y uu yw uw yw uw
or σ , σ , σ , σ or τ for wood and FRP — shall be taken
tu cu fu bu u
— in accordance with ISO 12215-5:2019, i.e. according to tests or default values specified in its Annex C for
FRP, its Annex E for sandwich core, and its Annex F for laminated wood and plywood,
— in accordance with Annex B for the listed metals, including, where relevant, ISO 3506-1 for stainless steel
fasteners and ISO 898-1 for carbon steel or alloy steel fasteners, and
— for other metals, either from a recognized standard or from tests made in accordance with the relevant
International Standard.
Table 2 — Design stresses and stress coefficients
Variable Material/designation Value
a
min. st ;,05×st
Metals, unwelded or well clear of HAZ ()
yu
bc,
st
LIM min. st ;,05×st
Metals, within HAZ, in welded condition ()
yw uw
a
bc,
Wood or FRP as dictated by sense of applied stress σ ,,,σσσ andτ as relevant
uc ut uf ub u c
Stress factor
Metals with elongation at break, ε % ≥ 7 0,75
R
k
MAT
Metals with elongation at break, ε % <7 min.(0,062 5ε + 0,312 5;0,75)
R R d
Wood and FRP 0,33
k Stress factor (see Table 3)
LC
Stress factor
k Craft of design categories A and B 1,00
DC
Craft of design categories C and D 1,25
a
Generally, the heat-affected zone is considered as being 50 mm from the weld (see F.3.4.3).
b
For metals, τσ=×05, 8 .
c
Bearing stress depends on material type (Ref [8] gives σσ = 2,8 for Glass CSM and 0,91 for roving), metal regulation
ub uc
usually gives 2,4 to 3 for bolts (but with restrictions: far from edges, min. bolt spacing, min. thickness/bolt d). Values derived
from tests are recommended.
d
The factor gives 0,75 for ε ≥ 7 %, and 0,375 for ε =1 % and linear interpolation in between. Values of ε are given in Table B.2.
R R R
Table 3 — Value of k stress factor according to load case
LC
Value of
Load case Keels and appendages — Load case description Subclause
k
LC
a
Keel bolt 7.2 0,67
1 Other elements of fixed keel—metal — 0,8
b
Other elements of fixed keel—FRP — 0,9
Canting keel—metal 7.3 0,8
Canting keel—FRP 7.3 0,9
Canting keel—metallic actuator/metallic actuator and keel support structure 7.3 0,8
Canting keel—FRP actuator/FRP actuator and keel support structure 7.3 0,9
3 Keel vertical pounding 7.4 1
a
Load case 1 treats bolts differently from other structural components. The design stress of bolts is lower than that of other
structural components in recognition of stress concentration effects in bolts, according to long-standing practice.
b
Caution: The requirements of this document are based on strength criteria. In some cases, such as keel fins constructed of
lower modulus materials, the need to limit deflections and/or increase natural frequencies may require a substantial increase in
scantlings above those requirements. Such cases are outside the scope of this document.

ISO/DIS 12215-9:2024(en)
TTabablele 3 3 ((ccoonnttiinnueuedd))
Value of
Load case Keels and appendages — Load case description Subclause
k
LC
4 Keel longitudinal impact 7.5 1
5 Dinghy capsize recovery (strength of centre/dagger board) 7.6 1,34
6 Centre/dagger board upwind 7.7 1,0
a
Load case 1 treats bolts differently from other structural components. The design stress of bolts is lower than that of other
structural components in recognition of stress concentration effects in bolts, according to long-standing practice.
b
Caution: The requirements of this document are based on strength criteria. In some cases, such as keel fins constructed of
lower modulus materials, the need to limit deflections and/or increase natural frequencies may require a substantial increase in
scantlings above those requirements. Such cases are outside the scope of this document.
6 Structural components to be assessed
CAUTION — Keel loss can be attributed to insufficient thickness of bottom plating in the keel region.
In particular, connecting bolts or inadequately assessed load paths between connecting bolts and
the corresponding structure and bolts located too far from the relevant stiffener are causative. It
is strongly recommended that the provisions of D.5 and Table D.2 be followed and, in particular,
for bolts located too far from a stiffener, those provisions of Table D.2, item 3. Keel loss can also be
attributed to insufficient fatigue strength of keel fins. In such cases, the provisions in Annex F should
be followed.
The following shall be considered when assessing or designing the structure covered by this document.
— Keel-to-hull connection (bolts, wedge connection, stub keel, etc.) — see Figures 1, C.3, C.4 and D.1.
— Bottom shell plating in respect of the keel bolts and transition arrangements beyond the keel bolting
zone into the hull structure. Keels should not be bolted to a hull bottom of sandwich construction. The
structural arrangement shall ensure that all loads — keel compression loads, bolt preload, etc. — are
safely transferred. Note that the terms “pre-stress” and “preload” are used interchangeably.
— Backing plates (usually rectangular steel plates installed on the hull plating inner surface that spread
load)/steel washers (annular, placed under securing nuts or bolt heads).
— Floors, girders and associated supporting structure.
— Keel boxes, canting keel actuators and support structure.
— Fins, centreboards, dagger boards of aerofoil cross-section (note: hydrofoils are not considered).
Assessment should be conducted either by numerical methods in accordance with Clause 8 or the established
practice methods given in Clause 9.
7 Load cases
7.1 General
7.1.1 Status of design load cases
CAUTION — For load cases 1 and 2 — where keels have a large sweep angle, the centre of gravity (CG)
of the bulb/fin can be located a significant distance aft or forward of the fin or bolt group longitudinal
centre at the root. This will induce a torsional moment in addition to the bending moment. In such
cases, it will be necessary to combine direct stresses owing to bending with shear stresses due to
the torsion. The resulting von Mises equivalent stress shall not exceed the design stress given in
Formula (1), also noting Clause 7.8. See also Clause 7.8.1.

ISO/DIS 12215-9:2024(en)
The design stress shall be assessed for each load case using Formula (1), together with the design stress
coefficients given in Table 2 and Table 3, as follows:
— 7.2 defines the fixed keel 90° knockdown load case 1 and corresponding force, F , and design bending
moment, M , at 90° heel, for the keel at its root/bolt level and floor neutral axis, respectively; it shall be
used for fixed keels, either vertical or angled as in the case of twin keel craft, and axially lifting or swing
ballast keels;
— 7.3 defines canted keel load case 2 and the corresponding force, F , and design bending moment, M , at
2 2
30° steady heel plus a dynamic overload factor; it shall only be used for canting keels;
— 7.4 defines vertical pounding load case 3 and design vertical force, F ;
— 7.5 defines longitudinal impact load case 4 and design horizontal force, F , that considers a longitudinal
impact with a fixed or submerged object or marine life;
— 7.6 defines dinghy capsize recovery load case 5 and the design vertical force, F , in 90° knockdown, applied
on the tip of a centreboard for dinghy capsize recovery;
— 7.7 defines centreboard/dagger board load case 6 and the transverse horizontal force, F , applied to
centreboard or dagger board used while sailing upwind;
— 7.8 considers other load cases, particularly where specific designs cause combined stresses.
7.1.2 Limitation of load cases
This document is based on the presumption that load magnitudes are set at such a high level of severity that
the number of expected occurrences during the lifetime of the craft will be low. Hence, all load cases are
considered to be static and used in conjunction with static design stresses according to Tables 2 and 3.
For keels of welded construction, compliance with the static load cases cannot guarantee that fatigue failure
due to cyclic loading will not occur. In such cases, an explicit fatigue life assessment and inspection regime
shall be considered (see Annexes A and F). It is of the utmost importance that the response of structures
experiencing cyclic loading is less than the fatigue strength. Fatigue analysis is required when the stresses
are high in magnitude and when structures feature welds that required detailed design and documentation.
Keel configurations resembling the types shown in Figure C.4 require case-by-case consideration.
In addition, the load cases consider that, for bolted connections, the methods for assessing keel bolts are
based on the presumption of a broadly uniform distribution of diameter and spacing along the fin root or
keel flange (see D.4 for details).
7.2 Load case 1 — Fixed keel at 90° knockdown
This case corresponds to a 90° knockdown case (heeled at 90°) (see Figure 1), which is usually the most
severe transverse bending load for fixed ballast keels:
Fm=×g (2)
1 KEEL
expressed in N as the vertical force, at 90° knockdown, exerted by gravity at the keel CG
MF=×a (3)
11. 1
expressed in N⋅m as the keel heeling design moment at the keel junction
MF=× ac+ (4)
()
12. 1
expressed in N⋅m, keel heeling moment at floor mid height

ISO/DIS 12215-9:2024(en)
where
a is the distance, in m, along the keel centreline, from the keel CG to the keel's junction with the hull
or stub;
c
is the distance, in m, along the keel centreline from the keel junction to the floor at mid-heigh;
g 2
is the acceleration due to gravity, taken as 9,81 m/s and used throughout this document.
The craft’s structure, keel connection and stiffeners shall be able to withstand this force and moments.
For craft fitted with a fin and stub [see Figure 1 b)], it may be necessary to consider a range of values of c to
establish the most highly stressed point.
Annex C provides information on how to calculate the shear force and bending moment on each floor when
these are analysed as independent beams.
NOTE For single fixed keels, when considered parallel to the centreline these bending moments correspond to a
heel angle of 90° knock-down. For fixed twin keels [see Figure 1 c)], the cosine of angle ϕ from the horizontal when the
craft is knocked down is not considered, as the keels will be parallel to the waterline at some point before or after the
craft reaches 90° of heel.
7.3 Load case 2 — Canted keel steady load at 30° heel with dynamic overload factor
7.3.1 General
This case only applies to canting keels [see Figure 1 d)]. It corresponds to a steady heel at 30° that can be
experienced as a long-term load, with an additional dynamic overload factor which represents the additional
fluctuating load experienced as the craft responds to the seaway.
Load case 2 represents the normal sailing condition for a craft with canted keel, but is augmented by a 40 %
2)
dynamic overload factor to allow for unusual combinations of rigid body motions and accelerations, and
is thereby considered to constitute an infrequently occurring case. Fatigue will still need to be considered,
noting Clause 7.1.2:
Fm=×14, ×g (5)
2 KEEL
expressed in N as the vertical force exerted by gravity at the keel CG
°
MF=×a×+sin 30 θ (6)
()
21. 2
expressed in N×m as the canting keel design heeling moment at the keel junction
where θ is the maximum canting angle from axial (vertical) plane and shall not be taken as greater than 60°
o
or less than 30 .
NOTE 1 The lower limit of 30° ensures a load at least 22 % greater than load case 1.
NOTE 2 Very thin fins of a canting keel, especially those of FRP construction, often require “flutter” (vibration)
analysis, but this is considered outside the scope of this document (see Clause 7.1.2 and Annex F).
For calculation of floors, the keel design heeling moment of supporting structure floors is
°
 
MF=× ac×+sin 30 θ +05, (7)
()
22. 2
 
expressed in N as the design bending moment of canting keel floors.
The craft structure, keel connection and stiffeners shall be able to withstand this force and moments.

2) The dynamic overload factor for normal sailing conditions is in the order of 15–20 % but may be higher.

ISO/DIS 12215-9:2024(en)
Annex C provides information on how to calculate the shear force and bending moment on each of the two
“wet-box” bulkheads when these can be analysed as independent beams.
a) Craft with axial keel heeled at 90° b) Craft with axial keel with stub keel
c) Craft with twin keels heeled at 90° d) Craft with canting keel heeled at 30°
Figure 1 — Sketch of fixed axial keel, twin keels and laterally canting keel
7.3.2 Specific requirements for canting keel structure
The canting keel system shall be fitted with a box that is watertight.
Structural elements shall be provided to support the loads from the canting keel, in case of leakage or a
defect in the orientation rams or system, and to protect the surrounding structure, such as stops, actuators
and locking pins.
7.4 Load case 3 — Keelboat vertical pounding
This case considers a vertical impact load in relation to the events of dry-docking or purely vertical and
upwards grounding:
Fg=−()mm (8)
3 LDCKEEL
expressed in N as the vertical pounding force exerted at keel bottom with the craft upright.

ISO/DIS 12215-9:2024(en)
The bending moment is not specifically given here as it depends of the floor and keel arrangement (number,
length, stiffness, end fixity, etc.). Annex C gives information on how to calculate the shear force and bending
moment on each floor when these may be analysed as independent beams.
The craft structure, keel connection and stiffeners shall be able to withstand a vertical force, F , exerted
at the ballast keel bottom, passing through the keel CG, without exceeding the grounding design stresses
defined in Clause 5.
For twin or multiple keels, 100 % of F is considered to be applied on the bottom of each keel and its structure
and attachment, as the grounding could happen on one keel. This will induce a bending moment for such
keels that shall be taken into account (see 7.8.2).
Canting keels are also to be considered in the “neutral” (cant angle of zero) position.
For lifting keels, this requirement applies to the worst case of deployed or retracted condition.
In the deployed condition, the lifting/deploying device shall
— either be able to support load F without surpassing the design stress, or
— retract without damaging the actuating system until the retracted condition is attained.
7.5 Load case 4 — Keelboat longitudinal impact
7.5.1 Value of longitudinal impact and bending moment
The craft structure and keel connection shall be able to withstand, without exceeding design stresses, a
longitudinal and horizontal force, F exerted at the bottom of the leading edge of the keel and which does
not need to be taken lower than 0,2L below the loaded waterline.
WL
CAUTION — The moments given in the following formulae are not the bending moments in the
various floors; see Annex C.
Fg=×12, ×−()mm (9)
4 LDCKEEL
expressed in N as the longitudinal and horizontal impact force
MF=×h (10)
41. 44F
expressed in N×m as the combined bending moment at the keel connection (root) from both longitudinal and
lateral horizontal impact forces.
MF=×()hc+ (11)
42. 44Fa
expressed in N×m as the combined bending moment at floor mid-height from both longitudinal and
transverse impact forces.
where
hh=min ;,02L , expressed in m, is the lesser of
()
F4 k WL
— the height of the keel, h measured parallel to the axial plane of the craft, between its bottom
k
and its connection to the hull or skeg (see Figure 1), and
— 0,2L , measured from the loaded waterline;
WL
c is the average vertical distance, in m, of the c values from the keel junction to the mid-height of the
a
loaded floor.
ISO/DIS 12215-9:2024(en)
For canting keels, h is measured with the keel oriented so as to have the maximal draft, with the craft
k
upright.
For twin or multiple keels, F is considered to be applied on each keel at the level of h , as defined above,
4 F 4
because the impact can be on only one keel when heeled.
For lifting keels, h is measured with the keel fully deployed. The device shall resist F in the worst case of
k 4
deployed or retracted condition.
In the deployed condition, the lifting/deploying device shall either
— be able to support F without surpassing the design stress, or
— retract without damaging the actuating system until the retracted condition is attained.
The centreboards and lifting keels that are not required by ISO 12217 to be locked in the deployed condition
need not be considered for the application of F .
NOTE For tilting centreboards, the lifting rope or ram usually acts as a breaking-pin. For dagger boards, the well
or a crash box acts as the device supporting F .
7.6 Load case 5 — Centreboard on capsize recoverable dinghies
On capsize recoverable sailing craft, as defined in ISO 12217, and where th
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