SIST EN ISO 12215-8:2009
(Main)Small craft - Hull construction and scantlings - Part 8: Rudders (ISO 12215-8:2009)
Small craft - Hull construction and scantlings - Part 8: Rudders (ISO 12215-8:2009)
This part of ISO 12215 gives requirements on the scantlings of rudders fitted to small craft with a length of hull, LH, of up to 24 m, measured according to ISO 8666. It applies only to monohulls. This part of ISO 12215 does not give requirements on rudder characteristics required for proper steering capabilities. This part of ISO 12215 only considers pressure loads on the rudder due to craft manoeuvring. Loads on the rudder or its skeg, where fitted, induced by grounding or docking, where relevant, are out of scope and need
to be considered separately.
Kleine Wasserfahrzeuge - Rumpfbauweise und Dimensionierung - Teil 8: Ruder (ISO 12215-8:2009)
Dieser Teil von ISO 12215 betrifft die Bestimmungen für Dimensionierung von Rudern, die an kleinen Wasserfahrzeugen mit einer Rumpflänge (LH) bis 24 m, gemessen nach ISO 8666, befestigt sind. Er gilt für Einrumpf-Wasserfahrzeuge und Mehrrumpf-Wasserfahrzeuge. Anforderungen für Rudereigenschaften zur ordnungsgemäßen Steuerung sind nicht enthalten. ANMERKUNG Dimensionierungen, die sich aus dieser Internationalen Norm ergeben, sind in erster Linie für Freizeitwasserfahrzeuge einschließlich Charterboote vorgesehen.
Petits navires - Construction de coques et échantillonnage - Partie 8: Gouvernails (ISO 12215-8:2009)
L'ISO 12215-8:2009 prescrit des exigences d'échantillonnage des gouvernails installés sur les petits navires d'une longueur de coque inférieure ou égale à 24 m, mesurées conformément à l'ISO 8666. Elle s'applique uniquement aux monocoques.
L'ISO 12215-8:2009 ne prescrit aucune exigence concernant les caractéristiques du gouvernail nécessaires à une bonne manoeuvrabilité.
L'ISO 12215-8:2009 prend uniquement en compte les charges de pression s'exerçant sur le gouvernail du bateau lors des manoeuvres. Les charges sur le gouvernail ou sur son aileron, lorsqu'il existe, induites par l'échouage ou l'échouement, le cas échant, sont en dehors du domaine d'application et nécessitent d'être prises en compte séparément.
Les échantillonnages établis à l'aide de l'ISO 12215-8:2009 sont principalement destinés à s'appliquer sur les bateaux de plaisance, y compris les bateaux de location ou de «charter».
Mala plovila - Konstrukcija trupa in zahtevane lastnosti - 8. del: Krmila (ISO 12215-8:2009)
Ta del ISO 12215 podaja zahteve glede zahtevanih lastnosti krmil, nameščenih na mala plovila z dolžino trupa, LH, do 24 m, merjenega v skladu z ISO 8666. Velja le za enotrupna plovila. Ta del ISO 12215 ne podaja zahtev glede značilnosti krmil, potrebnih za brezhibno zmožnost krmarjenja. Ta del ISO 12215 obravnava zgolj tlačne obremenitve krmilo, ki ga povzroči manevriranje plovila. Obremenitve krmila ali njegovega skega, kjer je nameščen in jih povzroči nasedanje ali dokiranje, kadar je to ustrezno, so zunaj področja uporabe in jih je treba obravnavati ločeno.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 12215-8:2009
01-julij-2009
Mala plovila - Konstrukcija trupa in zahtevane lastnosti - 8. del: Krmila (ISO 12215-
8:2009)
Small craft - Hull construction and scantlings - Part 8: Rudders (ISO 12215-8:2009)
Kleine Wasserfahrzeuge - Rumpfbauweise und Dimensionierung - Teil 8: Ruder (ISO
12215-8:2009)
Petits navires - Construction de coques et échantillonnage - Partie 8: Gouvernails (ISO
12215-8:2009)
Ta slovenski standard je istoveten z: EN ISO 12215-8:2009
ICS:
47.020.10 Ladijski trupi in njihovi Hulls and their structure
konstrukcijski elementi elements
47.080 ýROQL Small craft
SIST EN ISO 12215-8:2009 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 12215-8:2009
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SIST EN ISO 12215-8:2009
EUROPEAN STANDARD
EN ISO 12215-8
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2009
ICS 47.020.10; 47.080
English Version
Small craft - Hull construction and scantlings - Part 8: Rudders
(ISO 12215-8:2009)
Petits navires - Construction de coques et échantillonnage - Kleine Wasserfahrzeuge - Rumpfbauweise und
Partie 8: Gouvernails (ISO 12215-8:2009) Dimensionierung - Teil 8: Ruder (ISO 12215-8:2009)
This European Standard was approved by CEN on 21 April 2009.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12215-8:2009: E
worldwide for CEN national Members.
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SIST EN ISO 12215-8:2009
EN ISO 12215-8:2009 (E)
Contents Page
Foreword .3
Annex ZA (informative) Relationship between this International Standard and the Essential
Requirements of EU Directive 94/25/EC amended by EU Directive 2003/44/EC .4
2
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SIST EN ISO 12215-8:2009
EN ISO 12215-8:2009 (E)
Foreword
This document (EN ISO 12215-8:2009) has been prepared by Technical Committee ISO/TC 188 "Small craft"
in collaboration with CEN Sub-sector T01 “Shipbuilding and maritime structures”, the secretariat of which is
held by CMC.
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 November 2009, and conflicting national standards shall be withdrawn
at the latest by November 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] 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, and supports essential requirements of EC Directive(s).
For relationship with EC Directive(s), see informative Annex ZA, which is an integral part of this document.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 12215-8:2009 has been approved by CEN as a EN ISO 12215-8:2009 without any
modification.
3
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SIST EN ISO 12215-8:2009
EN ISO 12215-8:2009 (E)
Annex ZA
(informative)
Relationship between this International Standard and the Essential
Requirements of EU Directive 94/25/EC amended by EU Directive
2003/44/EC
This standard has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association to provide one means of conforming to Essential Requirements of the New
Approach Directive 94/25/EC amended by EU Directive 2003/44/EC.
Once this standard is cited in the Official Journal of the European Communities under that Directive and has
been implemented as a national standard in at least one Member State, compliance with the normative
clauses of this standard given in Table ZA.1 confers, within the limits of the scope of this standard, a
presumption of conformity with the corresponding Essential Requirements of that Directive and associated
EFTA regulations.
Table ZA.1 — Correspondence between this International Standard and Directive 94/25/EC amended
by EU Directive 2003/44/EC
Essential requirements (ERs) of EU
Clause(s)/sub-clause(s) of this
Directive 94/25/EC amended by EU Qualifying remarks/Notes
International Standard
Directive 2003/44/EC
The standard provides
All clauses Annex 1 A, Clause 3.1 structure
requirements for the structural
strength of rudders.
Single bearing spade rudders and
single hull bearing skeg rudders are not
addressed by this standard.
WARNING — Other requirements and other EU Directives may be applicable to the products falling
within the scope of this standard.
4
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SIST EN ISO 12215-8:2009
INTERNATIONAL ISO
STANDARD 12215-8
First edition
2009-05-15
Small craft — Hull construction and
scantlings —
Part 8:
Rudders
Petits navires — Construction de coques et échantillonnage —
Partie 8: Gouvernails
Reference number
ISO 12215-8:2009(E)
©
ISO 2009
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
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ii © ISO 2009 – All rights reserved
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols . 2
5 Design stresses . 4
5.1 Rudder material. 4
6 Rudder and steering arrangement, rudder types . 5
6.1 General. 5
6.2 Rudder types . 6
7 Design rudder force calculation. 10
7.1 General. 10
7.2 Force F and corresponding load case . 11
1
7.3 Force F and corresponding load case . 12
2
8 Rudder bending moment and reactions at bearings . 13
8.1 General. 13
8.2 Analysis of spade rudder (Type I). 13
8.3 Analysis of skeg rudders (Types II to V) . 14
9 Rudder design torque, T . 16
10 Rudder and rudder stock design . 17
10.1 Load bearing parts of the rudder . 17
10.2 Metal rudder stock material . 17
10.3 Design stress for metal rudder stock . 18
10.4 Required diameter for solid circular metal rudder stocks . 18
10.5 Vertical variation of the diameter of a Type I rudder (spade). 18
10.6 Round tubular stocks. 19
10.7 Non-circular metal rudder stocks . 20
10.8 Simple non-isotropic rudder stocks (e.g. wood or FRP). 21
10.9 Complex structural rudders and rudder stocks in composite. 21
10.10 Check of deflection of Type I rudder stocks between bearings . 21
11 Equivalent diameter at the level of notches.22
12 Rudder bearings, pintles and gudgeons. 22
12.1 Bearing arrangement. 22
12.2 Clearance between stock and bearings . 23
13 Rudder stock structure and rudder construction . 24
13.1 Rudder stock structure . 24
13.2 Rudder construction. 24
13.3 FRP rudder blades. 24
13.4 Non-FRP rudder blades. 25
14 Skeg structure. 25
14.1 General. 25
14.2 Design stress . 25
Annex A (normative) Metal for rudder stock . 26
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
Annex B (normative) Complex composite rudder stock design . 30
Annex C (normative) Complete calculation for rudders with skeg . 32
Annex D (informative) Geometrical properties of some typical rudder blade shapes . 36
Annex E (informative) Vertical variation of diameter for Type I rudders . 39
Annex F (informative) Type I rudders — Deflection of stock between bearings . 41
Bibliography . 44
iv © ISO 2009 – All rights reserved
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 12215-8 was prepared by Technical Committee ISO/TC 188, Small craft.
ISO 12215 consists of the following parts, under the general title Small craft — Hull construction and
scantlings:
⎯ Part 1: Materials: Thermosetting resins, glass-fibre reinforcement, reference laminate
⎯ Part 2: Materials: Core materials for sandwich construction, embedded materials
⎯ Part 3: Materials: Steel, aluminium alloys, wood, other materials
⎯ Part 4: Workshop and manufacturing
⎯ Part 5: Design pressures for monohulls, design stresses, scantlings determination
⎯ Part 6: Structural arrangements and details
⎯ Part 8: Rudders
© ISO 2009 – All rights reserved v
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
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, thus limiting the general worldwide
acceptability of craft. This part of ISO 12215 has been set towards the lower boundary range of common
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.
The working group considers this part of ISO 12215 to have been developed applying present practice and
sound engineering principles. The design loads and criteria of this part of ISO 12215 may be used with the
scantling determination equations of this part of ISO 12215 or using equivalent engineering methods such as
continuous beam theory, matrix-displacement method and classical lamination theory, as indicated within.
Considering future development in technology and craft types, and small craft presently outside the scope of
this part of ISO 12215, provided that methods supported by appropriate technology exist, consideration may
be given to their use as long as equivalent strength to this part of ISO 12215 is achieved.
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 equipped and operated at a speed appropriate
to the prevailing sea state.
vi © ISO 2009 – All rights reserved
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SIST EN ISO 12215-8:2009
INTERNATIONAL STANDARD ISO 12215-8:2009(E)
Small craft — Hull construction and scantlings —
Part 8:
Rudders
1 Scope
This part of ISO 12215 gives requirements on the scantlings of rudders fitted to small craft with a length of hull,
L , of up to 24 m, measured according to ISO 8666. It applies only to monohulls.
H
This part of ISO 12215 does not give requirements on rudder characteristics required for proper steering
capabilities.
This part of ISO 12215 only considers pressure loads on the rudder due to craft manoeuvring. Loads on the
rudder or its skeg, where fitted, induced by grounding or docking, where relevant, are out of scope and need
to be considered separately.
NOTE Scantlings derived from this part of ISO 12215 are primarily intended to apply to recreational craft including
charter craft.
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.
ISO 8666, Small craft — Principal data
ISO 12215-5:2008, Small craft — Hull construction and scantlings — Part 5: Design pressures for monohulls,
design stresses, scantlings determination
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
design categories
sea and wind conditions for which a craft is assessed by this part of ISO 12215 to be suitable, provided the
craft is correctly handled in the sense of good seamanship and operated at a speed appropriate to the
prevailing sea state
3.1.1
design category A (“ocean”)
category of craft considered suitable to operate in seas with significant wave heights above 4 m and wind
speeds in excess of Beaufort Force 8, but excluding abnormal conditions such as hurricanes
© ISO 2009 – All rights reserved 1
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
3.1.2
design category B (“offshore”)
category of craft considered suitable to operate in seas with significant wave heights up to 4 m and winds of
Beaufort Force 8 or less
3.1.3
design category C (“inshore”)
category of craft considered suitable to operate in seas with significant wave heights up to 2 m and a typical
steady wind force of Beaufort Force 6 or less
3.1.4
design category D (“sheltered waters”)
category of craft considered suitable to operate in waters with significant wave heights up to and including
0,3 m with occasional waves of 0,5 m height, for example from passing vessels, and a typical steady wind
force of Beaufort Force 4 or less
3.2
loaded displacement mass
m
LDC
mass of the craft, including all appendages, when in the fully loaded ready-for-use condition as defined in
ISO 8666
3.3
sailing craft
2/3
craft for which the primary means of propulsion is wind power, having A > 0,07(m ) where A is the total
S LDC S
profile area of all sails that may be set at one time when sailing closed hauled, as defined in ISO 8666 and
expressed in square metres
NOTE 1 For the headsails, A is the area of the fore triangle.
S
NOTE 2 In the rest of this part of ISO 12215, non-sailing craft are called motor craft.
4 Symbols
For the purposes of this document, unless specifically otherwise defined, the symbols given in Table 1 apply.
NOTE The symbols used in the annexes are not listed in Table 1.
2 © ISO 2009 – All rights reserved
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
Table 1 — Symbols, coefficients, parameters
(Sub)clause/table
Symbol Unit Designation/meaning of symbol
concerned
2
A m Total area of the moving part of the rudder 6.2.1, 6.2.3
2
A m Rudder effective area (Types II to IV) 6.2.3
0
2
A m Rudder blade area (Types II to IV) or top blade area (Type V) 6.2.3
1
2
A m Bottom rudder blade area (Type V) 6.2.3
2
2
A m Rudder skeg area [only used to determine type (see Figure 3)] 6.2.3
3
c m Rudder chord length at centre of area level 6.2.1, 6.2.2
c m Length of the top chord (Type I) 6.2.1
1
c m Length of the bottom chord (Type I) 6.2.1
2
co m Compensation at top chord (distance from LE to rotation axis) (Type I) 6.2.2
1
co m Compensation at bottom chord (distance from LE to stock CL) (Type I) 6.2.2
2
d mm Required solid stock diameter 10.4
d mm Inner diameter of tubular stock 10.6
i
d mm Outer diameter of tubular stock 10.6
o
F N Final side force on rudder 7.1
F N Side force on rudder in design category sea state 7.2
1
F N Side force on rudder during a turn at speed in slight sea 7.3
2
h m Height between rudder top and centre of hull bearing 6.2.1
b
h m Height between rudder top and centre of area 6.2.1
c
h m Height between rudder top and centre of skeg bearing (Type V) 6.2.3
d
h m Height between rudder bottom and centre of skeg bearing (Type V) 6.2.3
e
h m Height between centre of upper bearing and a point inside the hull (Type I) 6.2.1
in
h m Height between bottom of spade and a point outside the hull (Type I) 6.2.1
ou
h m Average height of rudder blade (see Figure 1) 6.2.1
r
h m Height of skeg from hull attachment to skeg bearing (Types II to V) 6.2.3
s
h m Height between centres of hull (lower) bearing and upper bearing 6.2.1
u
k 1 Rudder bending coefficient 6.2.1
b
k 1 Coefficient lowering force for flat or wedge rudder blade shape 7.3
FLAT
k 1 Coefficient lowering force due to gap hull/rudder top 7.2
GAP
k 1 Length displacement coefficient 7.2
LD
k 1 Coefficient for skeg deflection 8.3.4
S
k 1 Coefficient considering extra load due to sea in design categories A and B 7.2
SEA
k 1 Coefficient considering lower required service in design categories C and
SERV
7.3
D
k 1 Coefficient lowering design stress for F 7.3
SIG 2
k 1 Coefficient considering lower usage of craft with damage survey 7.2
USE
k 1 Fibre type factor 13.3.1.2
5
L m Effective length of the skeg 8.3.4
S
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
Table 1 (continued)
(Sub)clause/table
Symbol Unit Designation/meaning of symbol
concerned
L m Length at waterline, according to ISO 8666 in m conditions 7.2
WL LDC
M Nm Bending moments on the rudder stock or skeg 8
M , M Nm Bending moments at skeg or hull 8.3.4
S H
m kg Loaded displacement mass 3.2, 7.2
LDC
r m Horizontal distance from rudder force to stock axis 6.2.1
r m Minimum value of r 9
min
R , R , R N Reaction force at upper bearing, hull bearing, skeg bearing, respectively 8
U H S
t mm Skin thickness of tubular or hollowed closed section Table 6
T Nm Torque (twisting moment) on the rudder stock 9
u m Longitudinal distance from leading edge to stock axis at centroid chord 6.2.1
V knots Maximum speed of craft in calm water, m conditions 7.3
MAX LDC
2
w kg/m Minimum fibre mass per area of rudder blade 13.3.1.2
z m Effective bending moment lever z = k ⋅ h + h 8.2.1
b b b r c
z m Equivalent bending moment lever 10.4
eq
α 1 Tip chord to root chord ratio (c /c) 6.2.2
2 1
Λ 1 Geometric aspect ratio of the rudder 6.2.1, 6.2.3
2
σ N/mm Direct stress (ultimate, yield, design) 5
2
τ N/mm Shear stress (ultimate, yield, design) 5
χ 1 Ratio between reaction at skeg and rudder force 8.3.2
5 Design stresses
5.1 Rudder material
Values of design stresses shall be taken from Table 2
Table 2 — Values of design stresses
Stresses in newtons per square millimetre
Direct stresses
Combined
Material
Tensile/compressive Shear Bearing
stresses
σ τ σ
d d db
22
a
min σ ; 0,5 σ 0,58 τ 1,8 σ
()
Metals yu σ + 3τσu
d d
d
22
Wood and fibre-reinforced ⎛⎞ ⎛ ⎞
στ
0,5 × σ 0,5 τ 1,8 σ
+< 0,25
u u d ⎜⎟ ⎜ ⎟
plastics (FRP) ⎜⎟ ⎜ ⎟
στ
⎝⎠uu⎝ ⎠
a
Steel, stainless steel, aluminium alloys, titanium alloys, copper alloys (see Annex A). In welded condition for welded metals.
4 © ISO 2009 – All rights reserved
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SIST EN ISO 12215-8:2009
ISO 12215-8:2009(E)
In Table 2,
⎯ σ is the design tensile, compressive, or flexural strength (as relevant);
d
⎯ σ is the ultimate tensile, compressive, or flexural strength (as relevant);
u
⎯ σ is the yield tensile, compressive, or flexural strength (as relevant);
y
⎯ σ is the design bearing strength;
db
⎯ τ is the design shear strength;
d
⎯ τ is the ultimate shear strength.
u
Additional requirements are given in Annex A (metals) and Annex B (composites)
For wood and composites, the strength values of the relevant annexes of ISO 12215-5 shall be used.
6 Rudder and steering arrangement, rudder types
6.1 General
6.1.1 General definition
The rudder and steering arrangement comprises all components necessary for manoeuvring the craft, from
the rudder and the rudder operating gear to the steering position.
Rudder and steering equipment shall be arranged so as to permit inspection.
NOTE It is good practice that the rudder keeps the steering effect after grounding (for example, a spade rudder with
the stock not going down to the bottom enables the rudder blade to break without bending the stock).
6.1.2 Multi-rudder arrangement
If the craft has several rudders, the following requirements apply to each one of the rudders.
NOTE On sailing craft, twin rudders, frequently canted outwards, are not usually protected from contact with floating
objects by the keel, a skeg, the hull canoe body at centreline, etc. This is particularly the case for the windward rudder,
close to the waterline, that can also be hit by breaking waves and can therefore support a part of the craft's weight. It is
therefore current practice to have twin rudders installed on sailing craft that are significantly stronger than required in this
part of ISO 12215, which only considers loads from normal lift forces. This enhanced strength is not quantified here.
6.1.3 Vertical support
The rudder stock or blade shall be supported vertically with limited axial upwards movement.
6.1.4 Hard over stops
Rudder stocks that are, or can be, actuated by a remote steering system (i.e. not directly by the tiller) shall be
fit
...
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