Effective date: 2021-12-01
Status:Approved

International 420 Class
Association

The 420 was designed in 1959 by Christian Maury and was
adopted as a World Sailing class in 1973.

INDEX

C.7

Hull.................................................. 9

C.8

Hull Appendages............................. 9PART I – ADMINISTRATION

C.9

Rig.................................................. 10

Section A – General

C.10

Sails.................................................. 11

A.1

General Information………………….. 3

A.2

Language........................................... 3

A.3

Abbreviations..................................... 3

A.4

Authorities and Responsibilities…… 3

A.5

Administration of the Class................ 3

A.6

WS Rules........................................... 4

A.7

Amendments to Class Rules….......... 4

A.8

Class Rules Variations..……............. 4

A.9

Interpretations of Class Rules............ 4

A.10 ICA fee ICA Plaque………................ 4

Section D – Hull
D.1

Certification….................................. 14

D.2

Builders……..................................... 14

D.3

Building & Materials for Building...... 14

D.4

Assembled Hull................................ 15

D.5

Hull Weight……................................ 20

D.6

Corrector Weights............................ 20

Section E – Centreboard, rudder & tiller

4E.1

Rules................................................. 21

A.12 Validity of Certificates……………..... 5

E.2

Manufacturer......................................

A.11 Certification & certificate…………..

A.13 Re-Certification.................................. 5

21E.3

Section B – Boat Eligibility

Centreboard......................................

B.1

Certificate……………………………... 6

B.2

Certification marks. .......................... 6

B.3

ICA Sail buttons – stickers ….…........6

B.4

ICA Plaque ……….………………...... 6

B.5

Builder’s Plaque……………….…....... 6

PART II – REQUIREMENTS AND
LIMITATIONS

21
E.4

Rudder………….............................

22

Section F – Rig
F.1

Rules.................................................. 24

F.2

Mast................................................... 24

F.3

Boom................................................. 26

F.4

Spinnaker Pole.................................. 26

F.5

Rigging & fittings…………................ 27

Section C – Conditions for Racing

Section G – Sails

C.1

General............................................ 7

G.1

Measurement................................... 28

C.2

Crew................................................. 7

G.2

Certification….................................... 28

C.3

Personal Equipment........................ 7

G.3

Mainsail............................................. 29

C.4

Advertising...................................... 8

G.4

Headsail............................................ 31

C.5

Portable Equipment........................ 8

G.5

Spinnaker.......................................... 32

C.6

Boat.................................................. 8International 420 Class Rules 2021

2

PART I – ADMINISTRATION___________________________________________________________________

Section A – GENERAL
A.1

GENERAL INFORMATION

A.1.1

The International 420 class rules are closed class rules.

A.1.2

The 420 is a one-design class. The intention of these rules is to ensure that the boats
are as alike as possible in all respects affecting performance, in order that crews maycompete against each other on level terms.

A.1.3

These rules are complementary to the Lines plan (plan des formes), the building
specifications (Drawing N° 5), the International 420 Class Association (ICA) rudder
blade drawing and the 420 International Measurement Form (IMF). The current issue ofthese official documents is listed at the end of this document. These items, howevercomplete, cannot anticipate every situation that may arise. If a point is not clearly
covered, a ruling shall be obtained from WS through the ICA technical Committee.

A.2

LANGUAGE

A.2.1

The official language of the Class is English and in the event of dispute overinterpretation, the English text shall prevail.

A.2.2

The word “shall” is mandatory and the word “may” is permissive.

A.2.3

The term "permanent" shall mean unable to be removed with simple tools, or fixed withglue or rivets. For limit marks, it shall mean unable to be removed and repositioned
without destroying them.

A.2.4

All units are metric and all dimensions, unless otherwise stated, are in millimetres.

A.3

ABBREVIATIONS

A.3.1

WS
MNA
ICA
IMF
NCA
ERS
RRS

World Sailing
WS Member National authority
International 420 Class Association
420 International Measurement FormNational 420 Class Association
Equipment Rules of Sailing
Racing Rules of Sailing

A.4

AUTHORITIES AND RESPONSIBILITIES

A.4.1

The class rules authority is WS, which shall co-operate with the ICA in all mattersconcerning these class rules.

A.4.2

Neither WS, an MNA, the ICA, an NCA, a certification authority, or an official
measurer are under any legal responsibility in respect of these class rules and theaccuracy of measurement, nor can any claims arising from these be entertained.

A.4.3

Notwithstanding anything contained herein, the certification authority has theauthority to withdraw a certificate and shall do so on the request of WS.

A.5

ADMINISTRATION OF THE CLASSThe Class is administered by the ICA, in conjunction with WS. The ICA may delegate
parts or all of its functions, as stated in these class rules, to an MNA or an NCA.

International 420 Class Rules 2021

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A.6

WS RULES
These class rules shall be read in conjunction with the current version of the ERS.
When a term is used in its defined sense, it is printed in bold type if defined in the ERS
and in italic type if defined in the RRS.

A.7

AMENDMENTS TO CLASS RULES

A.7.1

Amendments to these class rules shall be proposed by the ICA and are subject to theapproval of WS in accordance with WS regulations.

A.8

CLASS RULES VARIATIONS

A.8.1

At World and Continental Championships and other ICA-sanctioned events the noticeof race and/or the sailing instructions may change the class rules only with theagreement of both the ICA and WS.
At other events the notice of race and/or the sailing instructions may change the classrules only with the written agreement of the ICA to an official request by the local NCA
and/or MNA.

A.8.2

A.9

INTERPRETATION OF CLASS RULES

A.9.1

GENERAL
Except as provided by A.9.2, interpretation of these class rules shall be made by WS
in conjunction with the ICA. Request for an interpretation shall be made in accordancewith WS regulations.

A.9.2

AT AN EVENT
Any interpretation of class rules required at an event may be made by the ICA
Technical Committee in consultation with the event chief measurer. Suchinterpretations shall be valid only during the event, and the ICA shall, as soon aspractical after the event, inform WS of such an interpretation.

A.10

ICA FEE, ICA PLAQUE

A.10.1The Sail number for each boat is allocated by the ICA and specified on the ICA Plaque.

A.10.2The ICA, after having received the class fee, shall send to the licensed builder the ICA
Plaque, with the sail number allocated to the boat.

A.10.3Competitors may use the sail number of any hull still owned by them, on any boat
chartered or owned by them.

A.11

CERTIFICATION AND MEASUREMENT CERTIFICATE

A.11.1

For a hull not previously certified, certification control for all items to be measured
and to be in conformity with the Official documents shall be carried out by an official
measurer, and the details entered into the IMF which, when completed, shall be
supplied to the owner by the builder in two copies.

A.11.2

Certification control shall be carried out only by official measurers appointed bothby their MNA and the ICA. An official measurer shall not perform certification control
on any part owned, designed or build by him, or in which he is an interested party, or
has a vested interest, except where permitted by these class rules.

A.11.3The IMF is necessary to obtain the measurement certificate. The measurement
certificate is obtained as follows:
The owner shall send the IMF together with any registration fee to the certification
authority in the country where the boat is to be registered. Upon receipt of asatisfactorily completed IMF and the fee, the certification authority issues themeasurement certificate to the owner. The certification authority shall retain a copyof the IMF.

International 420 Class Rules 2021

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A.12

VALIDITY OF THE MEASUREMENT CERTIFICATE

A.12.1

A certificate is still valid after an alteration of the corrector weights only if the hull is
re-weighed by an official measurer. When the hull is re-weighed, the measurer shallenter the details on the IMF and the measurement certificate shall be endorsed by thecertification authority.

A.12.2A measurement certificate becomes invalid upon:a) Change of ownership,b) Alterations other than permitted routine maintenance such as small repairs,
painting, sanding and polishing to items required by the IMF to be measured,c) Withdrawal by the certification authority,d) The issue of a new certificate.

A.13

RE-CERTIFICATION

A.13.1

Upon change of ownership, the new owner shall apply to the certification authority
where the boat will be registered for a new measurement certificate. The application
shall include the old measurement certificate, the original IMF, and any registration feethat may be required. A new measurement certificate shall then be issued to the newowner.

A.13.2

Upon alteration or repair to an item required by the IMF to be measured, the relevant
item shall be re-measured by an official measurer and the details entered on the IMF.
The owner shall apply for a new measurement certificate (see A.13.1 for theprocedure).

A.13.3

When the certificate has become invalid under A.12.2 (c), the certification authority
may issue a new certificate at its discretion.

International 420 Class Rules 2021

5

Section B – BOAT ELIGIBILITY
For a boat to be eligible to race, the rules in this section shall be complied with.
B.1

CERTIFICATE
No crew shall take part in class races unless the boat has a valid measurement
certificate, in English or with English subtitles, including corrector weight details.

B.2

CERTIFICATION MARKS
Each sail shall carry a valid certification mark according to G.2.1.

B.3

ICA SAIL BUTTONS - STICKERSEach sail first certified after 1st March 2005 shall have permanently fixed an officiallynumbered ICA royalty sail button or sticker.

B.4

ICA PLAQUE
The ICA Plaque shall be affixed to the hull, as specified in D.1.5. In case of loss, areplacement plaque shall be obtained from WS.

B.5

INTERNATIONAL 420 BUILDER’S PLAQUE
The builder’s Plaque shall be affixed to the hull, as specified in D.1.5

International 420 Class Rules 2021

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PART II – REQUIREMENTS AND LIMITATIONS________________________________________________________________
The crew and the boat shall comply with the rules in Part II when racing and when rules specify.
The Notice of Race may specify that compliance shall be in effect from the moment equipment ispresented for event inspection. Measurement to check conformity with rules of Section C is notpart of equipment certification control. Measurement shall be carried out in accordance with thecurrent version of ERS except where varied in this Part.

Section C – CONDITIONS FOR RACING
C.1

GENERAL

C.1.1

RRS CHANGES

C.1.1.1

If the average wind speed is clearly over 13 knots across the course the race
committee may signal in accordance with RRS Appendix P5 that pumping, rocking andooching are permitted. This changes rules RRS 42.2(a), RRS 42.2(b), RRS 42.2(c).

C.1.1.2

A crew member shall use no device designed to position his body outboard other thana trapeze, hiking straps and hiking aids worn under the thighs. This changes RRS 49.1

C.1.1.3

See C.10.3.1 & C.10.5.1 for changes to RRS Appendix G.

C.1.1.4

The total weight of personal equipment worn, excluding trapeze harness and clothing(including footwear) worn below the knee shall not exceed 9 kg. The trapeze harness
shall not be filled with ballast and shall have a maximum weight of 3 kg. This changes
RRS 50.1(b)

C.2

CREW

C.2.1

LIMITATIONS

C.2.1.1

The crew shall consist of two persons, each in contact with the boat.

C.2.1.2

No crew member shall be substituted during an event without the approval of the Race
Committee.

C.2.1.3

The crew shall be current members of a NCA which shall be in good standing with the
ICA.

C.2.2

RESPONSIBILITY OF THE CREW
It is the crew’s responsibility to ensure that the boat and personal equipment comply
with the class rules when racing.

C.3

PERSONAL EQUIPMENT

C.3.1

MANDATORY
When afloat, each crew member shall wear personal flotation device to the minimum
standard ISO 12402-5 (Level 50), or USCG Type III, or AS 4758 Level 50, or
equivalent. Inflatable buoyancy vests are not permitted.

C.3.2

OPTIONAL

C.3.2.1

A trapeze may be used, but only one member of the crew shall use a trapeze harness.
A crew member using a trapeze shall be in contact with the hull at all times except in
the situation of accidental movement and or a maneuver.

C.3.2.2

Electronic or mechanical timing devices which don’t have any other function /capability. No other electronic device shall be carried by the crew on board.

International 420 Class Rules 2021

7

C.4

ADVERTISING

C.4.1

CATEGORY
Advertising including competitor advertising is permitted in accordance with WS
Regulation 20 - Advertising code.

C.5

PORTABLE EQUIPMENT

C.5.1

FOR USEa) OPTIONAL
1)

Hand bailers, buckets, sponges

2)

One compass fixed to a mounting bracket. The compass shall not recess intoeither side tank or foredeck. The mounting bracket may be attached to themast or may be used to close the mast gate. If electronic, only a compass
with heading, heading memory and timing functions is permitted; Electronic ormechanical timing devices, which shall be removable.

3)
C.5.2

The Notice of Race or Sailing Instructions may require or permit additional
electronic equipment to be carried aboard (such as tracking devices, cameras
etc.)
Tools and spare parts such as blocks, shackles, ropes etc.

NOT FOR USEa) OPTIONAL
1) One paddleb) MANDATORY
1)

The boat shall be fitted with a floating towing rope of a minimum length of 8 m
and minimum diameter of 8 mm, secured to the mast and stored inside one of
the spinnaker bags.

C.6.

BOAT

C.6.1

WEIGHT
The boat shall have a minimum boat weight of 100 kg. A compass with associatedbracket, if present, shall be included in the boat weight. Corrector weights, including
any required by D.6, shall have a maximum weight of 2 kg.

C.6.2

FITTINGS
Rigging and fittings listed here under shall be fitted and used only as specified.
Except where otherwise specified, the direction of the control lines, sheets, and ropes
shall not be modified by means of shackles, rings, loops thimbles or holes in the boat.
Fittings listed here under shall comply with the current class rules. All fittings,
fastenings and local reinforcement for fittings shall be only for their normal purpose andshall not be used to increase the weight of the boat.

C.6.3

Non-slip material, tape and low-friction material not exceeding 4 mm in thickness may
be added to the boat as long as it does not change the stiffness of the respective part.

C.7

HULL

C.7.1

MODIFICATIONS AND MAINTENANCE

C.7.1.1

The hull shell, deck, bulkheads, centreboard case and cockpit floor as supplied by thelicensed builder shall not be modified in any way except as permitted by these classrules.

International 420 Class Rules 20218

C.7.1.2

Routine maintenance is permitted without re-measurement and re-certification.

C.7.1.3

If any hull moulding is repaired in any other way than described in C.7.1.2, an official
measurer shall verify on the certificate that the external shape is the same as before
the repair and that no substantial increase in stiffness, or other advantage has been
gained as a result of the repair. The official measurer shall also describe the details of
the repair on the certificate

C.7.2

FLOTATION

C.7.2.1

The hull shall have two side buoyancy tanks and one in the front. At initial certification
control, the measurer shall check the water-tightness of the buoyancy tanks,
inspection ports and drain plugs. If the buoyancy is unsatisfactory, the measurer shallnot sign the IMF until satisfactory remedial measures have been taken. Thereafter, it is
the responsibility of the competitor/owner to ensure the water-tightness of these tanks.

C.7.1.2

Inspection port covers and drainage plugs shall be kept in place when racing.

C.8

HULL APPENDAGES

C.8.1

LIMITATIONS
Only one centreboard and one rudder blade shall be used during an event except incase of loss or damage beyond repair. Such replacement may be made only with theapproval of the Technical Committee or, in its absence, the Race Committee.

C.8.2

CENTREBOARD(a) USEThe centreboard shall be fitted by means of an axis pin through a hole in thecentreboard case, which may include a bushing. When fully raised, no part of thecentreboard shall project below the hull surface.

C.8.3

RUDDER(a) USEThe rudder blade shall be in its fully lowered position as dictated by the rudder
downhaul or the safety pin.
No part of the rudder blade, when fully lowered, shall extend more than 540 mm below
the HDP. The leading edge of the rudder blade shall not be forward of a vertical line
through the HDP (see measurement diagram 2).

BASE LINE

540 MAXNO PART OF THE RUDDERSHALL BE FORWARD
A VERTICAL LINE THROUGH
THE HULL DATUM POINT

Diagram 2
C.8.4

MAINTENANCE
Routine maintenance is permitted.

C.9

RIG

International 420 Class Rules 20219

C.9.1

LIMITATIONS
Only one mast, boom and spinnaker pole shall be used during an event, except incase of loss of damage beyond repair. Such replacement may only be made with theapproval of the event Technical Committee or, in its absence, the Race Committee.

C.9.2

MAST

C.9.2.1

USE1) The fore and aft bend of the mast at the mast partner level may be limited bychocks

an optional system of single piece of rope working on the front face of the mastspar, one attachment, one grip and one cleat without moving parts, on top of themast partner.

an optional system of single piece of rope working on the aft face of the mast spar,
one attachment, one grip and one cleat without moving parts, on top of the mast
partner.

With the mast spar in its most forward position, the grip or end of rope of the aft bend
control shall not be more than 150 mm from the mast partner. With the mast in its aftmost position the grip of the forward bend control shall not be more than 150 mm fromthe mast partner.
2) The mast heel position shall not be adjusted on the mast step when racing.
3) Adjustable spreaders –if used- shall not be able to be remotely controlled, and shallnot be adjusted when racing.
4) The effective length of the shrouds shall not be adjusted when racing.
5) The forestay under tension shall be entirely in metal and shall prevent the mastfrom disengaging from the mast partners. To meet this requirement the widest sectionof the mast shall be within the mast partners when the mast rakes under its own
weight and the forestay comes under tension, as in Diagram 3. The forestay shall beconnected to the stemhead fitting with either: a shackle, a rigging plate with holes andpins, a steel wire rope strop of minimum diameter of 2 mm or any combination of theabove. Elastic rope tied on the forestay and the stemhead is permitted.

DIAGRAM 3
C.9.3

MAINTENANCE

C.9.3.1

Routine maintenance is permitted.

C.10

SAILS

C.10.1

MAINTENANCE

C.10.1.1

Routine maintenance such as sewing, mending and patching is permitted without recertification. Modified sails shall be re-certified and the official measurer shallplace a new certification mark on the sail with the new date of certification control.

International 420 Class Rules 202110

C.10.2

LIMITATIONS

C.10.2.1

Not more than one mainsail, one jib and one spinnaker shall be carried aboard when
racing.

C.10.2.2

Not more than one mainsail, one jib and one spinnaker shall be used during an event,except when a sail has been lost or damaged beyond repair, or when otherwise
specified in the Sailing Instructions. Such replacement may be made only with theapproval of the Technical Committee, or, in its absence, the Race Committee.

C.10.3

MAINSAIL

C.10.3.1

IDENTIFICATION
Identification shall comply with the RRS Appendix G except where mentioned
hereunder:
As an alteration to RRS Appendix G 1.3 (a), the following items shall be positioned oneach side of the sail as follows:(a) National letters above and below and adjacent to the second batten from thetop, port and starboard not overlapping each other, those on starboard side
being uppermost.
(b) Sail numbers above and below and adjacent to the third batten from the top,
port and starboard not overlapping each other, those on starboard side being
uppermost.
(c) Mainsails used in women’s only events shall carry a red rhombus (length of
diagonals minimum 240 mm, maximum 260 mm) above the top batten pocket
on both sides. The position should be approximately in the centre of the triangle
formed by the top batten pocket and the mainsail head. The rhombus may beretained for racing in other events.
(d) The 420 mainsail insignia as per G.3.1 may be replaced by a gold version
conforming to the same dimensions when at least one member of the crew isan Int. 420 Class World Champion.
(e) When required by a Notice of Race, a helmsman's national flag, nominal size
740 x 443 mm, shall be applied to each side of the mainsail, placed as shown in
the Figure “Mainsail Flag Location”, so that the shortest distance of the upper
aft corner of each flag is between 50 and 100 mm from the leech and the lower
edge between 50 and 100 mm above the lowermost batten pocket. The flags
shall be made by an ICA-approved manufacturer as listed at:

http://www.sailing.org/classesandequipment/I420.php

International 420 Class Rules 202111

50 – 100 mm

min 50 – max 100 mm

Mainsail Flag Location(f) Numbers and letters shall be in red, of a minimum width of 200 mm (except number
1 and letter I), of a minimum thickness of 45 mm and of a minimum height of 300 mm.
Other dimensions and indications regarding letters and numbers are specified in RRS
Appendix G.1.2 (b).
(g) All numbers, letters and the emblem shall be of paint or other, securely attacheddurable material.
C.10.3.2

USE

C.10.3.2.1 The sail shall be hoisted on a halyard. The arrangement shall permit hoisting andlowering of the sail while afloat with the boat upright.
C.10.3.2.2 The sail shall be set so that the highest visible point of it, projected at 90° to the mastspar, shall not be higher than the upper point, and the aft-most visible part of theleech, projected at 90° to the boom spar, is forward of the outer point on the boom.
C.10.3.2.3 Luff and foot bolt ropes shall be in the respective spar grooves or tracks.
C.10.4JIB

C.10.4.1

USE
The sail shall be hoisted on a halyard. The arrangement shall permit hoisting andlowering of the sail while afloat with the boat upright.

C.10.4.2

Only one steel luff wire of minimum diameter of 2 mm shall be fitted inside the jib luff
sleeve.

C.10.5SPINNAKER

C.10.5.1

Identification
Identification shall comply with RRS, except where mentioned hereunder:
As an alteration to RRS Appendix G 1.3 (c), national letters are optional at World andContinental or other ICA sanctioned events. National letters and numbers are optional
at national events.

International 420 Class Rules 2021

12

If positioned, national letters may be in line with the sail numbers. The colour of lettersand numbers is optional, but they shall be all of the same colour, fully painted, andshall contrast with the colour of the panel to which they are positioned, of a minimum
width of 200 mm (except number 1 and letter I), of a minimum thickness of 45 mm andof a minimum height of 300 mm. Other dimensions and indications regarding lettersand numbers are specified in RRS.
All numbers and letters shall be of paint or other, securely attached, durable material.
Numbers and letters, if on both sides, shall not overlap and shall be placed at different
heights with a minimum space of 60 mm.
C.10.5.2

USE
The sail shall be hoisted on a halyard. The arrangement shall permit hoisting andlowering of the sail while afloat with the boat upright.

International 420 Class Rules 2021

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Section D – HULL AND DECK
D.1

CERTIFICATION

D.1.1

The hull, before leaving the builder’s premises, shall be measured by an official
measurer who shall sign the declaration on the IMF that it complies with the classrules, lines plan and building specification (Drawing 5). Measurements to ensure theconformity of the hull are specified on the IMF but the intention is that beyond thesemeasurements, the hull shall completely conform to the Official Documents.

D.1.2

To be certified in conformity with the class rules, Lines Plan and Building specification(Drawing N° 5) the hull shall comply with the official documents in force at the time ofinitial certification control but all fittings shall comply with the current rules.

D.1.3

Templates used for certification control of hull shall be approved by WS.

D.1.4

Tolerances are only given to allow minor building errors and shall not be deliberately
used to alter the design. The official measurer shall report on the IMF what heconsiders being a departure from the intended nature and design of the hull, and themeasurement certificate may be refused.

D.1.5

No hull shall leave the builders’ premises without the ICA plaque and the builder'splaque affixed. The builder's Plaque shall mention:- The trade mark of the hull
- The name of the builder- The mould number for hulls certified after 1st January 2015
- The year of building.
The ICA plaque shall mention:- The WS logo
- The ICA logo
- The sail number allocated to the boat
The ICA plaque shall be affixed on the starboard side tank, close to the transom andthe builder's plaque on the inside transom (see also rules B.4 and B.5)

D.2

BUILDERS

D.2.1

International 420 hulls shall be moulded and assembled only by licensed builders.
Application for a licence shall be made to WS which shall consult with the ICA and the
MNA of the country where the builder has its yard, before granting a license. Hulls
shall be supplied only as permanently assembled boat units. Fittings may be produced
by any manufacturer

D.2.2

Licensed builders have the sole responsibility that their production moulds, plugs andassembled boats comply with the relevant class rules and official documents.

D.2.3

If a builder does not comply with the requirements quoted in the class rules and the
Official documents, WS may revoke the license on the recommendation of the ICA.

D.2.4

If a builder is found to have supplied a boat that does not comply with the rules inapplication, he shall be liable to rectify the error, and may have his license as a builder
withdrawn.

D.3

BUILDING AND MATERIALS FOR BUILDING

D.3.1

The hull shall be built in conformity with the building specifications (Drawing N° 5)

D.3.2

Materials used for building shall be those specified on the Building specification(Drawing N° 5). All boats from any one builder shall be built to the same detailed
specification submitted by the builder to WS. Any subsequent modifications have to beapproved by WS before implementation.

International 420 Class Rules 2021

14

D.3.3No less than 0.05 m3 of positive buoyancy shall be securely attached in each side tankto give approximately equal buoyancy laterally and longitudinally. The buoyancy shallbe of closed cell rigid foam, or alternatively of air containers of not less than two litres
each. It shall not be used as hull reinforcement.

D.4

ASSEMBLED HULL

D.4.1

DIMENSIONS AND MEASUREMENT

D.4.1.1

The hull datum point (HDP) is the intersection on the hull centre plane of the transom
external surface with the underside of the hull surface, both extended as necessary.
The aft measuring point (AMP) is the projection of the HDP on the baseline.

D.4.1.2

For certification control of hulls built after the 1st July 2007, the base line shall be set
at 200 mm below the HDP and 92 mm below the keel at 3780 mm from the HDP. All
measurements carried out from the HDP shall be made parallel to the baseline anddepth measurements perpendicular to the base line. Measurement sections shall be
perpendicular to the base line. Hulls built before July 1st 2007 shall be controlled using
either this arrangement or the baseline arrangement in force at the time of construction.

D.4.1.3

The hull length shall be minimum 4180 mm and maximum 4220 mm.

D.4.1.4

Measurement sections 1 to 10 shall be at the following positions from the HDP:
Section 1: at 380 mm from HDP.
Section 2: at 780 mm from HDP.
Section 3: at 1180 mm from HDP.
Section 4: at 1580 mm from HDP.
Section 5: at 1980 mm from HDP.
Section 6: at 2380 mm from HDP.
Section 7: at 2780 mm from HDP.
Section 8: at 3180 mm from HDP.
Section 9: at 3580 mm from HDP.
Section 10: at 3980 mm from HDP.
Vertical distance from baseline to underside of hull shell;at section 1
at section 2
at section 3
at section 4
at section 5
at section 6
at section 7
at section 8
at section 9
at section 10

D.4.1.5

Minimum
154 mm
116 mm
84 mm
55 mm
34 mm
20 mm
15 mm
24 mm
56 mm
129 mmMaximum
170 mm
132 mm
100 mm
71 mm
50 mm
36 mm
31 mm
40 mm
72 mm
145 mmCertification Control of boats shall be performed at sections 2, 5, 8, 9 & 10. If themeasurer is in doubt regarding the conformity of the hull to the lines plan, the hull may
be checked at all measurement sections. Prototype measurement for mould approvalshall be performed at all 10 stations.

International 420 Class Rules 2021

15

Hull
Datum
Point

116 min
132 max

24 min40 max34 min50 max200

Aft
Measurement
Point

92

780

1980

BASELINE

3180

Forward
Measurement
Point

3580
3780
3980

5

2

8

9

10

POSITION OF THE MEASUREMENT SECTIONS

Diagram 4
D.4.1.6

129 min
145 max

56 min72 maxSection templates shall be applied as shown on diagrams 5 and 6. The top of the deckat the sheerline as defined in the building specification shall be not more than 10 mmabove or below the sheerline marks on the templates. The gunwale shall touch thetemplates or clear by a maximum of 50 mm. Below line 1, the templates shall touch thehull or clear by not more than 16 mm, and the difference between the greatest andsmallest clearance shall not exceed 12 mm.
Measurement at sections
5&6

The Top of the deckat the sheerline shallbe within the limits specified
on the templates

Prolongationof hull

Measurement Point

LINE 1( 400 mm from the Base Line)0 min
below the line 1
16 maxTemplates shalltouch the hullat centre except
template 5

No measurement of hull shell

Diagram 5
Diagram 6

D.4.1.7

The stem template shall be applied as shown on measurement diagram 7. The
template shall touch the stem or clear by not more than 15 mm.

20 min40 max
523 min
543 max(without deck overlap)

HDP

200
BASELINE

Aft Measurement Point(Projection of HDP)
Vertical line

Diagram 8International 420 Class Rules 2021

16

D.4.1.8

The transom template shall be applied as shown on measurement diagram 8. The
distance between the transom and the template shall be minimum 20 mm andmaximum 40 mm except at the deck overlap.
The transom radius shall be checked in a horizontal plan located 400 mm above thebaseline. On each side, the curvature measured at 520 mm from the centreline shall be
26 mm minimum and 42 mm maximum (see measurement diagrams 9 and 10).

D.4.1.9

min 26, max 42,
measured on line 1

LINE 1

400 mmBASELINE

520 mmmin 26, max 42,
measured on line 1
CENTRELINE

Diagram 10

Diagram 9

D.4.1.10

The centreboard case shall be in position as shown on measurement diagram 11 andthe Drawing N° 5. The forward upper part of the centreboard case shall be 330 mm
minimum above the underside of the hull, and the aft upper part shall be 295 mm
minimum above the underside of the hull. Overall, the centreboard capping width
shall be a maximum of 170 mm.

295 MIN

330 MIN

BASELINE
1415 MIN
2510 MAX

Diagram 11

D.4.1.11

The hull shall conform to all the dimensions specified on the drawing N° 5.

D.4.1.12

The convex curve of the foredeck shall be measured by placing a 300 mm straight edge
on any part of the deck forward of the breakwater. In any plane the straight edge shallnot be flat against the surface of the deck.

D.4.2

ASSEMBLED HULL FITTINGS(a)

The fittings listed hereunder shall be fitted and used only as specified. Cleatsmentioned in these rules, may incorporate a hook or an over-cleat fairlead. A
cleat wedge under each cleat is permitted. Except when specified, the direction of
the control lines, sheets and ropes shall not be modified by means of shackles,

International 420 Class Rules 202117

rings, loops or holes in the boat. Control lines, ropes, sheets, halyards shall not
pass through the buoyancy tanks and/or the breakwater.

D.4.2.1(b)

No fittings, with the exception of: spinnaker sheet catcher(s), non-slip material on
the gunwale, rudder fittings and transom drainage flaps shall project beyond theoutboard edges of the gunwale or beyond the profile of the hull.

(c)

No fitting shall serve as an extension of the hull surface.

(d)Ballast other than corrector weights shall not be carried.

(e)Materials for permitted fittings are optional except that Titanium is prohibited.

MANDATORY, WITH POSITION OR DIMENSION SPECIFIED
The following fittings shall be positioned in accordance with the drawing N° 5 and shallbe used as specified(a)

One stem-head fitting for attachment of the forestay and the headsail. The
centre of the front hole of the stem-head fitting shall be at 4085 mm minimumand 4125 mm maximum from the HDP. Only one hole for the forestay and one
hole for the jib are permitted. The forestay shall be attached to the front holeand the jib shall be attached to the aft hole.

(b)

Two shroud plates for the shrouds, one for each side of the boat. The centreof the hole of the shroud plates measured on the centreline shall be at 2550
mm minimum and 2570 mm maximum from the HDP.

(c)

One mainsheet track or bar of any profile, made only of metal or GRP. It shallbe straight and fixed to the centreboard case capping. The track or bar shallhave a maximum height of 40 mm and a maximum width of 40 mm. The
centreline of the track or bar shall be fixed to the side tanks at 1400 mm
minimum and 1500 mm maximum from the HDP.

(d)

One mast step fixed on the keelson. The length of the mast step shall be 150
mm maximum. The forward end of the mast step shall be at 2890 mm
minimum and 2910 mm maximum from the HDP. The bearing surface of themast step shall be at 5 mm maximum from the top surface of the keelson.

(e)

Two jib fairleads, the measurement point of which shall be at 2020 mm
minimum and 2120 mm maximum from the HDP and 625 mm minimum fromthe centreplane. The fairleads shall be fixed directly to the buoyancy tanks(see diagram 12).

2020 MIN / 2120 MAX from HDP
Jibfairlead625 MINJib fairlead
Measurement Point
2020 MIN / 2120 MAX from HDP
625 MIN

Diagram 12(f)

One drain hole in each buoyancy tank, located near the transom, with adiameter of 15 mm minimum and 25 mm maximumInternational 420 Class Rules 2021

18

D.4.2.2

D.4.2.3(g)

A minimum of one inspection hole for each buoyancy tank with a minimum
diameter of 100 mm.

(h)

Two spinnaker bags located according to Drawing 5.

(i)

A minimum of one draining hole or port in the transom, with a maximum total
area of 80 cm². Hinged covers or other devices for closing draining ports ordrain holes in the transom. These covers or devices shall not obstruct therudder

MANDATORY, WITH POSITION OR DIMENSION OPTIONAL(a)

One block fixed to a mounting on the aft part of the centreboard case cappingor the keelson for the mainsheet. (See also Rule F.6.2.a.5).

(b)

One cleat without moving parts and one guiding block directly behind the cleat
for the kicking strap system.

(c)

Two rudder fittings (pintles or gudgeons) for the rudder.

(d)One swivelling cleat with moving parts fixed on the aft part or the centreboard
case capping or two cleats with moving parts on the side tanks for themainsheet.

(e)

Two cleats with moving parts, fixed on the side tanks, for the jib sheets.

(f)

Two cleats with or without moving parts, fixed on the side tanks, for the
spinnaker sheets.

(g)

One fairlead and one cleat with or without moving parts for the spinnaker
halyard.

(h)

One cleat without moving parts and one guiding block directly behind the cleat
for the spinnaker uphaul/downhaul system (adjusting the height of thespinnaker pole). An additional block, a rope and a device to attach the rope ispermitted between the mast and the cleat mentioned above. One fairlead at
the mast partner for the spinnaker pole downhaul rope. Mast fittings for the
spinnaker pole uphaul/downhaul are specified in F 2.4.15.

(i)

A maximum of six fairleads (also mentioned in F.5.1.2) for the elastic cord of
the two trapeze wires.

(j)

Two spinnaker fairleads or blocks for the spinnaker sheets.

(k)

A centreboard pin with optional bushing and washers.

OPTIONAL
The following fittings -if fitted- shall be used only as specified below:(a)One self-bailer(b)

Toe straps inside the cockpit area for the crew, adjustable by means of ropes
and knots or one cleat without moving parts, and elastic cord to keep themlifted up.

(c)Spinnaker catcher fitting(s) which shall not project outside the gunwale edges
or more than 150 mm beyond the bow.

(d)

One hook on each side of the hull, on shrouds/shroud plates or fixed on thedeck and at 100 mm maximum forward of the centre of the hole of the shroud
plates, to lead the spinnaker guy aft.

(e)

Devices for securing the spinnaker halyard while the spinnaker is not set

International 420 Class Rules 2021

19

D.5

(f)

Tubular covers at the lower end of shrouds or their adjusters and the lower
end of the forestay to ease the passage of the sheets and to prevent
snagging.

(g)

Stainless steel springs under blocks to prevent them from falling over.

(h)One non-electrical wind indicator at the mast head.

(i)

Sealing strips for the centreboard case slot of optional material.

(k)

Strips of a minimum length of 300 mm and maximum width of 30 mm to
reduce friction and/or the distance between the centreboard and centreboard
case, but no device shall be attached to the inside of the centreboard casethat could cause the centreboard to gybe (angle to windward).

(l)

A moulded insert in the thwart or a device to secure the spinnaker pole in the
cockpit.

m)

Jib tack adjustment system, consisting of a shackle on the stemhead fitting,one cleat without moving parts mounted on the foredeck, one fairlead directly
behind the cleat and a rope.

(n)

One Cunningham control system of rope with a maximum of two singlesheave blocks. One cleat without moving parts and one guiding block directly
behind the cleat for the mainsail Cunningham line on the centerboard casecapping

HULL WEIGHTThe hull weight, including stem head fitting, shroud plates without shroud adjusters, allfixed fittings, complete hiking straps, rudder pintles or gudgeons, self-bailer, mainsheet
track/bar, centreboard pivot pin, inspection port covers, spinnaker bags and corrector
weights, but excluding the control lines, sheets and portable equipment shall be 80
kg minimum in dry condition.

D.6

HULL CORRECTOR WEIGHTS
If the hull weight according to D.5 is found to be less than 80 kg, corrector weights ofa maximum total weight of 2 kg shall be bolted to the upper inside surface of thetransom. The number and total weight of correctors shall be recorded on the IMF andthe measurement certificate. Corrector weights shall not be removed or alteredwithout the hull being re-weighted by an official measurer.

International 420 Class Rules 2021

20

Section E - CENTREBOARD, RUDDER AND TILLER
E.1

RULES
Centreboard and rudder shall comply with the current class rules.

E.2

MANUFACTURERS
The manufacturer is optional.

E.3

CENTREBOARD

E3.1

The centreboard shall be of even thickness, minimum 16 mm and maximum 20 mm
throughout, except that it may be bevelled to a maximum distance of 105 mm from theedges. Except for permitted bevelling, the thickness shall not vary by more than 1 mm.

E.3.2

The centreboard shall be made from one or a combination of the following materials;
wood, plywood, polyester resin reinforced with glass fibre, epoxy reinforced with glass
fibre and/or plastic foam which includes micro-balloons, and may be painted.

E.3.3

The profile of the centreboard shall conform to the dimensions and tolerances
specified on the measurement diagrams 13 & 14.
Lines (OA) and (OE) build the reference axes for length and width respectively, andshall be square to each other. Point (O) is the origin for both axes.

85
85

415 Min 425 max

The profile of the centreboard is defined by the points A, origin O, E, G, the lines (GH)and (AI)

Diagram 13
Point A is on the X axis, 910 mm from origin.
Point B is on the X axis, 85 mm from origin.
Point C is on the Y axis, 85 mm from origin.
The centreboard shall always touch points A, B and C, which are integral to it.
Point F is the point on the trailing edge 85 mm from axis Y.
Point G is on the trailing edge at 995 mm from Y axis.
Point E is the extension of the trailing edge (FG) on the Y axis.
Point D is the point on the lower edge 85 mm from point E, measured along axis Y. It
shall be not more than 2mm from axis Y.

The trailing edge (FG) is parallel to the x–axis: the distance of point (G) from theoutmost point of the leading edge, measured along y-axis, shall be equal to width (OE)International 420 Class Rules 2021

21

within 2 mm. At no point the width of the centreboard shall be more than 425 mm orless than 415 mm.

minimum
maximum
Distance from the centre of the pivot hole to the x–axis
75 mm
85 mm
Distance from the centre of the pivot hole to the y–axis
910 mm
930 mmDistance from E to the x–axis
415 mm
425 mmTotal (positive, negative or both) deviation of an edge from a straight line:
Between points A and B from the x–axis ......................................... ............. 2 mm
Between points C and D from line (CD) .......................................... ............. 2 mm
Between points F and G from line (FG) ........................................... ............. 2 mm
Point I is on the X-axis. Lines (AI) and (GH) are parallel. The profile of the centreboard
inside area HGAI is free, but no part of it shall lay outside this area.
The shape of the lower corners of the centreboard shall lie within the shaded areas indiagram 14, and no part of the bottom edge of the centreboard shall lie outside thepolygon formed between points B, B’, C’, D’, F’ and F.
Point B’ is the point on the x-axis 45 mm from origin O.
Point C’ is the point on the y-axis 45 mm from origin O.
Point D’ is the point on the y-axis 45 mm from point E.
Point F’ is the point on line (EG), 45 mm from point E.

Shape is free inshaded area

B

F'

D
E

45

D'

45

85

B'

45

85

F

C
C'
45

85

85

Diagram 14

E.3.4

Only the following fittings are permitted:(a) One centreboard uphaul of rope and/or elastic using a maximum of three singlesheave blocks and two cleats without moving parts. A cleat wedge is permitted undereach cleat, and a fairlead in front of/or integral to the cleat.
(b) One centreboard downhaul of rope and elastic, one fairlead and/or one block andone cleat without moving parts on the centreboard case capping. A wedge is permitted
under the cleat.

E.3.5

The direction of the control ropes used for the adjustment of the centreboard shall be
modified only by means of the blocks and fairlead and block specified in rule E.3.4.

E.4

RUDDER

E.4.1

The profile of the rudder blade shall conform to the dimensions and tolerances
specified on the Diagram 15 (same as the official 420 rudder blade drawing - AugustInternational 420 Class Rules 2021

22

2000)

E.4.2

The rudder blade shall be of even thickness, minimum 16 mm and maximum 20 mm
throughout, except that it may be bevelled to a maximum distance of 105 mm from theedges. Except for permitted bevelling, the thickness shall not vary by more than 1 mm.

E.4.3

The rudder stock shall be made of aluminium alloy and/or stainless steel and the tillerof wood or aluminium alloy. Strips of any material may be added to reduce friction
and/or the distance between the rudder stock and rudder blade. The rudder stock
shall not act as an extension of the hull. The rudder blade shall be made of one or a
combination of the following materials; wood, plywood, polyester with glass fibre, epoxy
with glass fibre and/or plastic foam, which includes micro-balloons and may be painted.

E.4.4

Only the following fittings are permitted:(a) One rudder downhaul made of one stainless steel wire and/or rope and elastic
and one cleat without moving parts on the tiller (a wedge under the cleat ispermitted), or a safety pin or bolt through the rudder head and rudder blade to
fix the rudder blade position.
(b) One tiller extension, which may be telescopic and of any material.
(c) One universal joint between tiller and extension.
(d) One rudder pivot pin.

E.4.5

A safety device shall be fitted so that the rudder stock cannot separate from the hull if
the boat capsizes.

International 420 Class Rules 2021

23

Section F - RIG
F.1

RULES
Rigs shall comply with the current class rules.

F.2

MAST

F.2.1

MANUFACTURER
Manufacturer is optional.

F.2.2

MATERIALS
The mast spar shall be of aluminium alloy. It may be anodised or painted.

F.2.3

CONSTRUCTION
The mast shall include a fixed sail groove or track, which may or may not be integral to
the spar but shall be of aluminium. Rotating and permanently bent masts areprohibited but a mast spar curvature measured at any place of the mast between theupper and lower points, of a maximum of 40 mm is permitted.

F.2.4

FITTINGS
The following fittings are mandatory and shall be used as specified:

F.2.4.1

A mast head fitting which may include the upper sheave for the mainsail halyard.

F.2.4.2

The direction of the halyards shall be modified only by means of the blocks, sheaves orfairleads specified in Section F of the class rules, except that the mainsail halyard mayturn through the halyard shackle on the mainsail head to form a 2:1 purchase.

F.2.4.3

One lock near the masthead or one lock, cleat or tooth rack below the gooseneck forthe mainsail halyard.

F.2.4.4

A maximum of two blocks, sheaves, or fairleads for each halyard (mainsail, jib,spinnaker). These blocks or sheaves shall be fixed on the spar.

F.2.4.5

The upper jib halyard sheave, block or fairlead shall be positioned so that the headsail
hoist height is less or equal to theforestay height

F.2.4.6

No part of the upper spinnaker halyard sheave, block or fairlead shall project more than
40 mm from the foreside of the mast.

F.2.4.7

The positions of rigging points of the shrouds, forestay and trapeze wires shall be at
the distances mentioned in F.2.7 (see shrouds, forestay and trapeze heights).

F.2.4.8

A pair of fixed or adjustable metal spreaders, with optional attachment systems. The
spreader height shall be at the distance stated in F.2.7. Optional devices may be
attached to the spreaders and/or the rigging to prevent the spinnaker halyard fromgetting tangled.

F.2.4.9

One spinnaker pole fitting on the foreside of the mast, with a maximum projection of
45mm.

F.2.4.10

One gooseneck, fixed to the mast to connect the boom to the mast.

F.2.4.11

One cleat without moving parts below the gooseneck and one rope, for the mainsail
Cunningham line if the system in D.4.2.3(n) is not present.

F.2.4.12

A tensioning system for the jib halyard made of two blocks with a maximum of six
sheaves in total, and one cleat. This cleat may have moving parts and shall be fixed at
one of the two blocks. The system shall be attached via a hook or a shackle to the jib
halyard, and at the other end to the mast or the mast step fitting, by means of a wire
strop or shackles and an attachment to the mast (tang, mast anchor plate etc).

F.2.4.13

One rope or a device around the mast and through the mainsail tack cringle to secure
the mainsail tack.

International 420 Class Rules 2021

24

F.2.4.14

A protection device around the mast at the mast gate

F.2.4.15

One spinnaker pole uphaul / downhaul made of rope and elastic and one hook. The
spinnaker pole uphaul / downhaul may be fitted with two plastic balls. For the
adjustment of the spinnaker pole uphaul / downhaul, only the following fitting ispermitted, one eye or block on the foreside of the mast, located below the forestay andshroud rigging points. One eye or block or fairlead on the foreside of the mast at thelevel of the mast partner. Two blocks, sheaves, or fairleads at the bottom of the mast.
(Additional fittings for the spinnaker pole uphaul/downhaul are stated in D.4.2.2.(j)).

F.2.4.16

One kicking-strap (boom vang) attachment fitting

F.2.4.17

A mast heel fitting which may include the lower sheaves for the halyards andspinnaker pole uphaul / downhaul.

F.2.4.18

Permanently painted / taped limit marks in a contrasting colour.

F.2.4.19

A device for preventing the mainsail from being set above the upper point, to ensurecompliance with C.10.3.2.2, unless the mainsail halyard is set on a lock or tooth rackas in F.2.4.3.

F.2.5

DIMENSIONS
Unless otherwise specified, all longitudinal measurements shall be carried out from themast datum point. For this purpose, the mast datum point (MDP) is located at themast heel point.

minimum

F.2.6

F.2.7

F.3
F.3.1

50 mm

maximum
6260 mm
75 mm

45 mm

75 mm

Mast length
Fore and aft mast spar cross section between 1550
mm and 4500 mm from the MDP
Transverse mast spar cross section within 4500 mm
from MDP
Mast limit marks width
Lower point height
Mainsail luff mast distanceHeadsail Hoist Height4520 mm

Spinnaker hoist height
Shrouds, forestay and trapeze heights
Spreader height4550 mm2550 mm

10 mm
1160 mm
4900 mmactualforestayheight4650 mm
4650 mm2650 mm

WEIGHT
The mast weight, with fittings specified in F.2.4 but without the tensioning system
mentioned in F.2.4.12 and the rope mentioned in F.2.4.13, and including fittings
specified in F.5.1 without the elastic cord and the four fairleads stated in F.5.1.2 andwith the length of elastic at the level of the spreaders as stated in F.5.1.2, shall beminimum 7.5 kg.
The centre of gravity of the mast, including fittings and rigging listed in F.2.6 with the
shrouds, forestay, trapeze wires and halyards secured along the mast, shall be at 2400
mm minimum from the mast datum point. For the measurement, the halyards shall behoisted and the halyard tails outside the mast shall be kept in hand by the measurer.

BOOM
MANUFACTURER
Manufacturer is optional.

F.3.2

MATERIALS
The boom spar shall be of aluminium alloy. It may be anodised or painted.

International 420 Class Rules 2021

25

F.3.3

CONSTRUCTION

F.3.3.1

The boom shall include a fixed aluminium sail groove or track, which may or may not
be integral to the boom spar.

F.3.3.2

The boom spar shall be of the same cross section throughout and shall not betapered.

F.3.4

FITTINGS

F.3.4.1

MANDATORY

F.3.4.1.1

A kicking-strap (boom vang) attachment (eye, plate, or hole through the boom)

F.3.4.1.2

Two mainsheet block attachments (eyes, plates, or holes through the boom)

F.3.4.1.3

A gooseneck attachment /front end fitting

F.3.4.1.4

One aft end fitting which may incorporate one sheave; one outhaul consisting of rope, amaximum of one block, one cleat without moving parts and optional elastic cord; aguiding block for the cleat may be used. The outhaul rope may pass through themainsail clew cringle and terminate on the aft end fitting.

F.3.4.1.5

A device for preventing the mainsail from being set outside the outer point, to ensurecompliance with C.10.3.2.2

F.3.4.1.6

Permanently painted / taped outer limit mark in a contrasting colour.

F.3.4.2

OPTIONAL

F.3.4.2.1

Ropes or devices through the cringles and around the boom to secure the mainsail atthe clew and the tack.

F.3.4.2.2

Protective devices where the boom touches the shrouds, of any material (maximum
length / height / thickness = 100 mm /50 mm /5 mm)

F.3.5

DIMENSIONS
Vertical boom spar cross section
Transverse boom spar cross section
Boom limit mark width
Outer point distance

F.4

SPINNAKER POLE

F.4.1

MANUFACTURER

minimum
55 mm
32 mm
10 mm

maximum
89 mm
76 mm
2400 mm

Manufacturer is optional

F.4.2

MATERIALS
The spinnaker pole spar shall be made of aluminium alloy. It may be anodised or
painted.

F.4.3

FITTINGS

F.4.4

Only the following fittings are permitted:(a) End fittings and control line which may incorporate knots, toggles or shorttubes for easier handling.
(b) Fittings approximately at the midpoint for attachment for uphaul/downhaul.
DIMENSIONS
The maximum spinnaker pole length is 1750 mm.

International 420 Class Rules 2021

26

F.5

RIGGING AND FITTINGS

F.5.1

RIGGING
The standing rigging shall comply with the current class rules. Certification is not
required. The following rigging shall be used, and consist of only:

F.5.1.1
F.5.1.2

A forestay and one shroud on each side, to support the mast. These shall be of steel
wire rope with a minimum diameter of 2 mm. Rod rigging is prohibited.
One steel trapeze wire, with a minimum diameter of 2 mm, on each side for the use of
one person only. Each trapeze adjustment system shall be provided with a maximumof one handhold, two sheaves, a ring or hook, an elastic cord, one rope, and one cleat.
The trapeze wires may be substituted with rope for a maximum length of 500mm fromthe handhold top. The two trapezes shall be connected to the hull by elastic cord witha maximum of six fairleads as stated in D.4.2.2.(i). Elastic is permitted to keep eachtrapeze wire clear of the spreaders and shrouds. Self-tacking trapeze systems are
not permitted.

F.5.2

FITTINGS

F.5.2.1

Each shroud shall be attached to the shroud plates by means of plates having rows ofadjustment holes and pins. No other method of shroud adjustment is permitted.

F.6

RUNNING RIGGING

F.6.1

MATERIALS(a) Materials are optional.

F.6.2

PARTS
(a) MANDATORY(1) Mainsail halyard(2) Headsail halyard(3) Spinnaker halyard, the tail of which may be attached to an elastic rope(4) Spinnaker pole lift and downhaul(5) Mainsail sheet that shall have four single-sheave blocks, one of which may be aratchet block. The mainsheet shall be attached to the block which is connected to thebridle. Two blocks shall be attached directly to the boom. The fourth block shall be
fixed to a mounting on the aft part of the centreboard case capping or keelson. The
maximum obtained purchase shall be 4:1.
(6) Jib Sheet(7) Spinnaker Guy and Sheet(8) A mainsheet bridle made either of:i) Two strops, either of rope or wire. Each strop shall be attached to a point on themainsheet bar/track or its end fittings, and to the mainsheet block, so forming a
triangle. Each strop may be adjustable by including one additional permanently fixedeyelet and one snap hook/shackle fixed at the track/bar or its end fittings, orii) Two strops of rope. The strop of each side shall pass through a sheave or blockattached to the end fittings of the mainsheet track/bar, and then end in a cleat without
moving parts, fixed on the mainsheet track/bar. One sheave and one cleat per side
are the only fittings permitted.
Any other adjustment system is prohibited.
(9) One kicking strap (boom vang) of rope and/or stainless steel wire with a maximumof five single-sheave blocks.
(b) OPTIONAL

International 420 Class Rules 2021

27

(1) Mainsail Cunningham line(2) Mainsail outhaul(3) Mainsail tack attachment

International 420 Class Rules 2021

28

Section G – SAILS
G.1.

MEASUREMENT

G.1.1

Unless otherwise specified in these rules, sails shall comply with the current classrules.

G.1.2

Jibs may be measured with battens inside the batten pockets.

G.1.3

Jib luff wires shall be removed for measurement.

G.1.4

The following applies to jibs certified after January 1, 2014:
When the tack or the clew has a cut-out, the corner point shall be found byextending the associated sail edges beyond the cut-out starting points and thenfinding the intersection point, as shown in diagrams G.4.1.7(a), G.4.1.8(a) andG.4.1.8(c).
(ii) An FRP batten of uniform stiffness and approximately 2 mm in thickness shall be
used to create sail edge extensions.
(iii) For clew cases as in G.4.1.8(c), not more than 100mm of the batten’s length
shall be used for sail edge extension purposes. For other cases such as a tackcorner with a cut-out as in G.4.1.7(a) and a clew corner as in G.4.1.8(a), notmore than 50mm of the batten’s length shall be used for sail edge extension
purposes.
(iv) The batten shall be held at points outside the part used for extensions.
(v) The batten shall be positioned with one point approximately at the expected
corner point and a second point, touching the sail edge to be extended, awayfrom the first point, at a distance not greater than the batten length specified in(iii).
(vi) If the sail edge is curved, the batten shall be bent to follow the sail edge
between the cut-out starting point and the second point described in (v). See thediagrams in G.4.1.7 & G.4.1.8.
(vii) The procedure above shall be repeated to find the other sail edge extension.
(viii) Rule G.1.4 modifies ERS H.5.4.
(i)

G.2

CERTIFICATION

G.2.1

The official measurer shall certify mainsails and jibs at the tack, and spinnakers at
the head, and shall sign and date the certification mark. The mainsail and thespinnaker may be certified without letters and numbers, but they shall comply when
racing with Class rules C.10.3.1 and C.10.5.1

G.2.2

A WS In-House Certification (IHC) Authorizing Authority may appoint one or more InHouse Official Measurers at a sailmaker to measure and certify sails produced bythat manufacturer in accordance with the WS guidelines.

G.2.3

For the mainsail and jib, the weight in g/m2 of the body of the sail shall be indelibly
marked at the head by the sailmaker together with the date and his signature or stamp.

G.2.4

Each sail first certified after 1st March 2005 shall have permanently fixed an officiallynumbered ICA royalty sail button or sticker, located for mainsails and headsails at thetack and spinnakers at the head. No sail shall be accepted for certification control
without a sail button / sticker. Sail buttons / stickers shall not be transferred from a sailto another.

G.2.4

SAILMAKER
Sailmaker is optional.

International 420 Class Rules 2021

29

G.3

MAINSAIL

G.3.1

EMBLEMhe 420 emblem shall be in dark blue, positioned below and adjacent to the top batten
pocket and conform to the dimensions and requirements mentioned in the diagramwith a tolerance of +/- 2 mm (see diagram 16).

R20
R5
147

45

17°
R20

R5

R5
R5

R5

R20

R10

R5

R10
R10

R5
40

480

R5

R20
R20

R20 R5
355
350
310
270

R5

R10

R5

R20

R5

190
150
40

R5
R20

115
120
135
160

R10
R35

220
235
265
280
335
380

Diagram 16
G.3.2

CONSTRUCTION

G.3.2.1

The construction shall be: Soft sail, single-ply sail.

G.3.2.2

The body of the sail shall consist of the same woven ply throughout except for thepanel adjacent to the foot, which may be of a different woven ply. This limitation does
not apply to the colour of the ply. The ply fibres shall be of polyester. Primary andsecondary reinforcement permitted material is woven ply with polyester fibres.

G.3.2.3

The weight of the ply of the body of the sail shall be minimum 150 g/m2.

G.3.2.4

The following are permitted:
Stitching, glues, tabling, tapes, bolt ropes for the luff and the foot, one cringle/eye ateach sail corner, one headboard with fixings, one Cunningham eye, batten pocket
patches, batten pocket associated fittings, one batten pocket end cap and one
batten tensioning device for the top batten pocket, one boom slide at the clew, leechline with cleat on leech, sail shape indicator stripes, tell tales, ICA sail button or sticker,
sailmaker’s trade mark, not more than two windows.

G.3.2.5

The ICA sail button / sticker shall be fixed in the tack.

International 420 Class Rules 2021

30

G.3.2.6

The leech shall not extend aft of straight lines between:(1) The aft head point and the intersection of the leech and the upper edge of thenearest batten pocket,(2) The intersection of the leech and the lower edge of a batten pocket and theintersection of the leech and the upper edge of an adjacent batten pocket below,(3) The clew point and the intersection of the leech and the lower edge of thenearest batten pocket.

G.3.2.7

The sail shall have four batten pockets in the leech, positioned as in Diagram 17.
Positions will be measured with the leech flattened by flaking/folding the mainsail.

G.3.3

DIMENSIONS (SEE DIAGRAM 17)
Minimum
Leech length
Quarter width
Half widthThree-quarter width
Upper width at upper leech point(600 mm from the head point)
Top Width
Flutter patches size
Chafing patches size
Primary reinforcement at corners
Secondary reinforcement at corners
Batten pocket patch size
Extension of the centreline of the top
batten pocket to the luff from the headpoint
Inside batten pocket length of lowermost
Inside batten pocket length of the twointermediate
Lowermost batten lengthIntermediate batten length
Inside Batten pocket width
Total Window opening Area
Window opening to the sail edge
Foot boltrope length for sails first certified
after 1st March 2003

International 420 Class Rules 2021

Maximum
5400 mm
2130 mm
1630 mm
995 mm
480 mm
115 mm
100 mm
900 mm
300 mm
900 mm
150 mm1420 mm1470 mm
540 mm
700 mm
540 mm
700 mm
60 mm
0.3 m2150 mm1920 mm31

600

MAIN SAIL DIAGRAM

4801470 max
1220±501420 min995

2220±50700 max1630
3220±50

5400 max

4220±50700 max

2130

540 max

Diagram 17
G.4

JIB

G.4.1

CONSTRUCTION

G.4.1.1

The construction shall be: Soft sail, single-ply sail. The leech shall not extend
beyond a straight line between the aft head point and the clew point (i.e. shall not be
convex).

G.4.1.2

The body of the sail shall consist of the same woven ply throughout, this limitation
not applying to the colour. The ply fibres shall be of polyester. Primary and secondary
reinforcement permitted material is woven ply with polyester fibres.

G.4.1.3

The weight of the ply of the body of the sail shall be minimum 150 g/m2.

G.4.1.4

The jib may have a maximum of three batten pockets in the leech.

G.4.1.5

The following are permitted: Stitching, glues, tapes, tabling, one cringle / eye at each
sail corner, not more than two windows, tell tales, a rope for the luff tension
adjustment and one cleat in the tack area, a steel wire rope inside the luff sleeve, sailbutton / sticker, sailmaker’s trade mark.

G.4.1.6

The sail button / sticker shall be fixed in the tack.

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32

G.4.1.7

Only the following tack construction arrangements are permitted for jibs certified afterJanuary 1 2017.

(a)G.4.1.8(b)

Only the following clew construction arrangements are permitted for jibs certified afterJanuary 1 2017.

(c)
(a)

G.4.2

(b)

DIMENSIONSLuff length
Leech length
Foot length
Foot median
Top width
Foot irregularity for sails first certified after 1st March 2010
Flutter patches size
Batten pocket inside length
Batten pocket patches
Chafing patches size
Primary reinforcement at corners
Secondary reinforcement at corners
Total Window opening area
Window opening to the sail edge

Maximum
3500 mm3200 mm
1750 mm
3360 mm
40 mm
30 mm
100 mm
200 mm
150 mm
900 mm
300 mm
900 mm
0,1 m2
Minimum
150 mmG.5

SPINNAKER

G.5.1

CONSTRUCTION

G.5.1.1

The construction shall be: Soft sail, single-ply sail. The sail shall be symmetricalabout its centreline.

G.5.1.2

The body of the sail shall consist of the same woven ply throughout, this limitation
not applying to the colour. The ply fibres shall be of polyester or polyamide. Primaryand secondary reinforcement permitted material is woven ply with polyester or
polyamide fibres.

G.5.1.3

The following are permitted: Stitching, glues, tapes, corner eyes, tell tales, sail button /sticker, sailmaker’s mark.

G.5.1.4

The sail button / sticker shall be fixed in the head.

International 420 Class Rules 2021

33

G.5.2DIMENSIONS
Leech Length
Foot Length
Half Width
Primary Reinforcement at corners
Secondary Reinforcement at corners
Foot Median for sails first certified after 15th March 2007

Maximum
4000 mm
2220 mm2840 mm
300 mm
900 mm4650 mm__________________________________________________________________OFFICIAL DOCUMENTS:
International 420 Class Rules
Lines plan (Plan des formes) issue C (August 2004)
Building specification (Drawing N° 5) issue H (February 2009)
International 420 Rudder Blade Drawing (August 2000)
International Measurement Form (December 2017)
Official templates used for measurement:
BOW (ISSUE C); C1 (ISSUE B); C2 (ISSUE B); C3 (ISSUE B); C4 (ISSUE B); C5 (ISSUE B); C6(ISSUE B); C7 (ISSUE B); C8 (ISSUE B); C9 (ISSUE B); C10 (ISSUE B) AND STERN (ISSUE Bor C).

Effective Date:
Published Date:

1st December 2021
29th November 2021

Previous issue:

1st October 2017

International 420 Class Rules 2021

34