Materials

(i)

Permitted materials: The hull, including deck, side tanks, bulkheads, centreboard case and all structural components shall be made of wood, plywood, glass reinforced plastic (GRP) or any combination of these materials. Sandwich construction, whose total thickness is not more than 12mm is permitted. The type of material used as a sandwich core or filler is optional except as prohibited by rule 3.2.1(ii). Any type of resin may be used.

(ii)

Prohibited materials: Fibres of carbon, boron, aromatic polyamides (such as Kevlar) or other high tensile materials, including any listed in the ISAF catalogue of materials classified as exotic, are prohibited.

Construction and measurement datum

(i)	The 'aft measurement point' (AMPt) shall be the intersection of the underside of the hull on the centreline with the transom, both extended if necessary.
(ii)	The 'aft measurement plane' (AMPn) shall be a transverse plane through the AMPt perpendicular to the base line. It is vertical.
(iii)	The 'base line' shall be as shown on the measurement diagram. It is horizontal.
(iv)	For the purpose of rule 3.2.2(i) the transom is an imaginary surface enclosed by the aft end of the underside of the hull shell and a line joining the port and starboard sheerlines at the aft end of the hull shell.
(v)	The centreline plane is a vertical plane through the baseline. For measurement purposes the hull should be arranged so that this plane goes through the AMPt and the top of the underside of the hull at station 3. For hulls first measured before 1st March 1997 and subsequently re-measured, the first and second sentences of Rule 3.2.2(v) are not mandatory.

Hull shell

The outside surface of the hull shall be a fair curve as defined by the lines:

(i)	Aft of station 4 the curve shall be convex or flat except that concavities of not more than 1.0mm measured below a fore and aft straight edge of any length are permitted.
(ii)	Forward of station 4 the curve shall be convex, flat or concave except that concavities, measured below a straight edge in the horizontal plane shall be not more than 2.5mm and in any other plane shall be not more than 18mm.
(iii)	The radius of the stem, measured in the horizontal plane, is optional.
(iv)	The width and position of the centreboard slot shall be as shown on the measurement diagram. A recess is permitted extending not more than 30mm from each side of and not more than 50mm from each end of the centreboard case slot to accommodate the slot gasket. The depth of the recess is optional.
(v)	Rubbing strakes shall be not wider than: (a) 20mm at the stem. (b) 40mm at transom, including inwale and transom, but shall not extend more than 20mm aft of the AMPn. (c) 40mm elsewhere.
(vi)	The depth of the rubbing strake shall be not more than 25mm, except that the underside may be faired to the hull shell by a fillet or fairing of radius not more than 25mm provided that, when hull measurement templates are correctly positioned, any such fillet or fairing is entirely within the minimum rubbing strake cutout area of the templates.
(vii)	Holes in the transom are permitted but shall be not more than 0.02m 2 in total area. These holes may be covered by hinged flaps or fixed windows of any material.
(viii)	Stiffening webs or stringers of any material permitted for hull construction may be fitted to the inner surface of the hull forward of the main bulkhead and inside the side tanks.
(ix)	No part of the outer face of the transom shall be more than 20mm from the AMPn.

Cockpit and deck

The external surface of the deck, sidetanks, main bulkhead and centreboard case shall have a fair profile as shown on the drawings except where varied by these rules.

(i)	Main bulkhead (a) There shall be a main bulkhead at 2000mm ± 20mm from the AMPn. (b) The bulkhead shall have not more than 2 hatches with watertight covers. A hatch whose opening has an area more than a circle of 150mm diameter shall be for maintenance access only. It shall be bolted, screwed or securely clipped into place at other times. (c) The bulkhead may have not more than two drainholes with watertight plugs or non-return valves which allow water to flow out of but not into the compartment forward of the bulkhead. (d) The bulkhead may have not more than eight lead holes for control lines provided they are not in a part of the bulkhead which forms a boundary of the forward buoyancy unit or tank required by rule 3.2.6. Each hole shall be not more than 7mm in diameter and shall be within an area enclosed by lines 100mm from the floor of the hull, the side tanks and the line of the foredeck. Any such holes not occupied by control lines shall be plugged.
(ii)	Sidetanks: The sidetanks shall extend from the main bulkhead to the transom. The shape shall be as defined by the lines: (a) the distance between the vertical faces of each side tank shall be 660mm ± 20mm at the inner face of the transom and 740mm ± 20mm at the main bulkhead. (b) The radius of curvature between the top and sides shall be 130mm ± 20mm. (c) Each side tank shall have at least one drain hole, with watertight plug, and/or hatch with watertight cover.
(iii)	Centreboard Case: (a) The centreboard case shall have sides of single skin or sandwich not more than 12mm thick. It shall be rigidly fixed to the bulkhead at its forward end over not less than 25mm of its depth measured from the top of the case. (b) The centreboard case capping shall be not more than 65mm wide each side, measured from the slot, and not more than 65mm deep. (c) A step to accommodate mainsheet blocks may be added to the centreboard case which shall be not more than 200mm from the slot, and not more than 100mm deep and wide. (d) The upper, aft end of the slot shall be not less than 1510mm from the AMPn. (e) The width of the slot shall be 20mm ± 2mm. (f) The distance, measured along the keel from the AMPt, to the aft end of the slot at the keel line shall be not less than 1465mm and to the forward end shall be not more than 2005mm. (g) At station 7 the distance from top of the case to the height of the sheerline shall be 184mm ± 10mm. (h) The top of the centreboard case shall be parallel to the base line within a tolerance of 10mm. (i) Pads of any resilient material may be fitted inside the top and bottom of each end of the slot to protect the edges of the centreboard. (j) Strips of any material may be fitted inside the top and/or bottom of the case to reduce friction and/or to match the slot width to the centreboard thickness provided the permitted dimensions of the case are not infringed.
(iv)	Thwart (a)   A thwart of width 105mm ± 45mm and depth 25mm ± 10mm shall connect any part of the vertical face of each side tank, abreast the aft end of the centreboard case, with the upper part of the centreboard case at the after end. In wooden construction the thickness shall be not less than 15mm; in GRP construction the thickness shall be not less than 3mm.  (b)  The thwart may be integral with the centreboard case capping.  (c)  Support struts and stiffening webs are optional.  (d)  As an alternative to (iv)(c), in GRP construction only, the forward and aft vertical faces of the thwart moulding may extend down the vertical face of the side tanks as stiffening webs not more than 45mm wide and with a radius of not more than 100mm between the web and the underside of the thwart.
(v)	Foredeck The foredeck shall have a fair profile as shown on the drawings except that on each side of the centreline not more than one step in the profile, of not more than 5mm in height, is permitted within the overall profile limits set by the tolerances for the sheer height and the deck camber at the main bulkhead. The deck camber at the main bulkhead shall be 52mm ± 10mm and at station 3 shall be not more than 30mm.
(vi)	Shaped pads, which may be an integral part of the moulding in GRP boats, are permitted on curved surfaces of the deck, side tanks and cockpit floor to accommodate flat based, permitted, fixed fittings. No part of a pad shall be more than 20mm from the line of the curved surface on which it provides a flat base. One vacant pad may be provided on each side of the boat as an alternative position for overdeck or underdeck control line cleats.
(vii)	Stiffening webs, stringers or beams of any material permitted for hull construction may be fitted to the inner surface of the foredeck and sidetanks.
(viii)	Centreline and other battens or pads for stiffening or support of hiking straps are optional. They shall be not more than 30mm deep.
(ix)	Except where otherwise specified the radius of any fairing, flange or fillet between hull components (e.g. main bulkhead, sidetanks, centreboard case, transom, thwart, foredeck) shall be not more than 25mm. The width of flanges used to secure hull components to each other is optional provided the 12mm sandwich thickness limitation is not infringed.
(x)	Spare number
(xi)	A centreline knee or strut of any material may be fitted between the inside face of the transom and the floor of the cockpit. No part of it shall extend more than 200mm from the transom nor more than 50mm from the centreline of the hull. In GRP hulls it may be moulded integrally with a centreline stiffening batten permitted by rule (viii) above.
(xii)	A stiffening beam (inwale) not more than 25mm deep may be fitted to the top of the inside of the transom. The overall width of inwale, transom and rubbing strake shall be not more than 40mm.

Fitting and equipment

(i)	Permitted fixed fittings are: (a) Hatches, hatch covers, drains, drain plugs and non return valves as permitted or required elsewhere in these rules; (b) 2 gudgeons on the stern to connect the rudder stock so that every rudder stock fits every hull. See Class Rule 3.4.5 (iv) and Rudder Blade Measurement Diagram for details of fittings and grandfather clause. (c) A rudder stock retaining device; (d) Not more than 3 hiking straps, which may be padded, and an adjustment system for each comprising not more than 2 single sheave blocks and 1 cleat; (e) A mainsheet block which may be a ratchet type; (f) A mainsheet traveller system comprising track, carriage, mainsheet block, 4 single sheave control line blocks and 2 cleats; (g) Control systems for cunningham, clew outhaul, tack inhaul and boom kicker (vang) each comprising not more than 6 single sheave blocks and 2 cleats; (h) Not more than 8 lead eyes or sheaves and sheave boxes fitted in main bulkhead for control lines; (i) A painter/towing line fairlead fitting at the stem head, which is mandatory; (j) A mast heel fitting, which may incorporate an adjustment system for the fore and aft position of the heel of the mast provided no part of the adjustment system can extend aft of a plane 500mm forward of the main bulkhead and the fore and aft movement of the heel of the mast in any setting of the adjustment system is not more than 5mm; (k) A deck bearing ring for the mast which shall be fixed and shall have no moving parts; (l) Not more than 4 automatic (self) bailers; (m) Not more than 2 retaining devices for water bottles; (n) Fastenings, including shackles where appropriate, for fittings listed.
(ii)	Fitting types and material are optional except that the use of fittings which are oversize, relative to their specific function, to add or concentrate weight is prohibited.
(iii)	Fittings and equipments not defined as fixed in Rule 3.2.5(i) are optional except that any electronic or electrically powered fitting or equipment other than a timing device is prohibited. They shall be removed for weighing and weight distribution tests.
(iv)	Rigging. Any form of standing rigging is prohibited. Except where otherwise specified in these rules the type, material, size and length of line, rope or wire used for running rigging is optional.

Buoyancy

(i)	There shall not be less than three separate buoyancy units which shall comprise the two side tanks and a forward buoyancy unit.
(ii)	The forward buoyancy unit may be provided by any one or combination of the following: watertight compartment(s); closed cell foam block(s); air bag(s). Not less than 30 litres of the unit's total volume shall be forward of the mast. The forward buoyancy unit, if it is a compartment or compartments, shall be: (a) isolated from the mast position by a watertight bulkhead or bulkheads. (b) fitted with not less than one inspection hatch with watertight cover and/or drainhole with watertight plug.
(iii)	Buoyancy tanks shall be watertight. On first measurement the measurer shall carry out tests on each tank as follows: Super or sub-atmospheric air pressure shall be applied to the tank sufficient to produce a differential reading of 130mm on a water gauge. The pressure differential shall not reduce from 130mm to less than 50mm in less than 30 seconds.
(iv)	After satisfying the buoyancy test detailed in 3.2.6.(iii) a pressure equalising hole, made with a nominal 2mm drill, may be provided in not more than one hatch cover or drainhole plug in each buoyancy unit. Sailing Instructions may require that any such hole be sealed.

Weight

(i)	The hull in dry and clean condition, with permitted fixed fittings, as defined in rule 3.2.5(i) shall weigh not less than 45kg. Mainsheet and control lines, except those forming part of the hiking strap or traveller control systems, shall be removed for weighing.
(ii)	If the hull is found to weigh less than 45kg, but not less than 40kg, a lead corrector weight, or weights, shall be securely fastened to the forward or aft face of the main bulkhead not lower than 200mm from the bottom of the hull. The weight (kg:g) and ISAF plaque number of the boat shall be stamped or engraved on each corrector weight.
(iii)	The hull weight, without correctors, and the weight and number of corrector weights shall be recorded on the certificate.
(iv)	Corrector weights shall not be removed or changed except after reweighing of the hull by an official measurer. The measurer shall record any change on the measurement certificate and send details to the certificating authority.

Weight Distribution

(i)	Any attempt to concentrate the weight of the hull is prohibited.
(ii)	The weight distribution, as defined by the fore and aft mass moment of inertia (I) and the location of the centre of gravity (CG) relative to the aft measurement plane, ie horizontal CG (CGH) and the underside of the hull on the centreline vertically below the CG, ie vertical CG (CGV), shall be determined, for the hull in the same condition as for weighing. 'I' shall be calculated from a radius of gyration (RG) measured using the method detailed on measurement diagram, sheet (vii) and the hull weight.
(iii)	If 'I' is less than 35.5kg/m 2 (which is the 'I' given by a radius of gyration of 888mm and a hull weight of 45kg) lead corrector weights, marked as in Rule 3.2.7, shall be securely fitted on the centreline, 50% forward of station 3 and 50% aft of station 10.
(iv)	The CGH shall be not less than 1500mm from the aft measurement plane.
(v)	The CGV shall be not less than 200mm above the underside of the hull on the centreline.
(vi)	If CGH and/or CGV is outside the limits specified lead corrector weights, marked and positioned as in Rule 3.2.7, shall be fitted.
(vii)	Corrector weights required to bring weight, weight distribution and centre of gravity within permitted limits shall be applied in that order. Weights required to correct weight distribution and centre of gravity shall be additional to those required to correct for weight.

Materials

The centreboard shall be made of wood, which may be laminated, of plywood or GRP with or without a plastic foam core, or of any combination of these materials. If of hollow construction there shall be an expansion/drain hole, which shall not be covered, at not more than 80mm from an upper corner.

Materials

The rudder blade shall be made of wood, which may be laminated, of plywood or GRP with or without a plastic foam core, or of any combination of these materials. If of hollow construction there shall be a drain/expansion hole, which shall not be covered, at not more than 80mm below the top of the blade.

Rudder Stock and Tiller

The materials, type and shape of rudder stock, tiller and tiller extension and associated fittings are optional except that:

(i)	the rudder blade shall be able to pivot about its axis in the rudder stock so that it may be lifted during launching and recovery of the boat. A fixed rudder blade is prohibited.
(ii)	A lanyard, locking pin and/or clamping screw and nut shall be fitted to secure the rudder blade in the fully down position.
(iii)	The profiles, cross sections and dimensions of the fittings shall comply with those specified on the rudder blade measurement diagram and the measurement form.
(iv)	The fittings to connect the rudder stock to the hull shall be made so that every rudder stock fits every hull. This shall apply for new rudder stocks and boats first measured after 1 March 1998 and all rudder stocks and all boats after 1 March 2000.
(v)	The weight of the complete rudder stock, tiller and tiller extension assembly, but excluding rudder blade, shall be not less than 1.25kg.

General

(i)	The intention of these rules is that masts should be of reasonable cost, reliable, and as uniform as possible, whilst allowing sufficient variation in stiffness to suit a wide range of helm body weights. The rules are framed to discourage the use of expensive materials and production methods, and to prevent developments in the aerodynamic shape.
(ii)	Concentration of weight of the mast by the use of Fittings, Materials or Laminates, even if otherwise permitted within these rules, is prohibited.
(iii)	In case of doubt the ISAF and the IECU may prescribe any tests and investigations, (including, but not limited to, destructive tests) to check rule compliance of the mast at manufacturer's expense.

Mast Builders

(i)	Masts may be built only by manufacturers who have been authorised by the IECU with the approval of ISAF. Authorised Manufacturer status will be granted to applicants based on their technical ability to produce good quality masts in accordance with these rules. Each Authorised Manufacturer will be issued with a unique Authorised Manufacturer Code (AMC) which must be shown on each mast made in accordance with rule 3.5.4 (ix).
(ii)	Prototype measurement is obligatory for all manufacturers to ensure that any prototype mast measures correctly before series production commences. Prototypes shall only be measured by measurer specifically authorised by ISAF and IECU.
(iii)	The ISAF and or IECU will require specification and samples of laminates to check compliance with class rules. A manufacturer shall permit a measurer or class representative, authorised by IECU, to inspect work at any time during production of masts or fittings.

Permitted Mast Material

(i)	The basic mast section (including sail track but without fittings) shall be made of FRP (Fibre Reinforced Plastic)·
Permitted mouldable fibres Shall be Carbon fibres, Glass-fibres, Aramid-fibres or any combination thereof. The fibre volume fraction of the laminate shall be > 50% Resin Shall be either: Polyester, Vinylester, Epoxy or Polyurethane. Shall only be used as a matrix to enclose the fibres. Coating A coating of any paint may only be used at the outer skin of the mast.
	No other materials as prescribed above shall be used to construct the basic mast section.
(ii)	The mast Fittings and Fasteners shall only be made of : stainless steel, brass, copper, aluminium alloys, plastic, FRP or any combination thereof.
(iii)	Metal or plastic washers and backing plates to fasten fittings shall be of max. thickness 2mm, and of max diameter: 3x nominal diameter of it's fastener. Below station 4500 a metal plate of alloy max dimension 4 x 30 x 400mm is allowed for fasten corresponding fittings at the aft face of the mast.
(iv)	An inflatable plastic tube weighing not more than 70 g/m· is permitted to remain inside the mast section.

Construction and Measurement

(i)	The mast shall comply with the dimensions and requirements specified on the mast design specifications and measurement diagrams and/or the measurement form.
(ii)	The tolerances on the design shape are as stated in the mast design specifications and measurement diagrams.
(iii)	The mast heel fitting and deck ring shall be mounted concentric to the mast section within ± 1mm.
(iv)	The mast shall be hollow throughout its whole length. In order to facilitate inspection of the internal mast section, the heel fitting shall be open or removable without damage.
(v)	To provide class statistics and information for sailors, 10 mast bend measurements (5 transverse and 5 fore-&-aft) shall be obtained as prescribed on the mast measurement diagram.
(vi)	The mast shall pivot on its heel. It shall be supported only at the heel and the deck ring.
(vii)	The mast shall be secured in position in the boat when sailing so that the heel cannot be lifted out of the mast step in any mast position.
(viii)	A manufacturer shall issue with each mast a measurement form issued by IECU. This form shall have three sections, i.e.: a) An Authorised Manufacturers Declaration (AMD) duly signed and filled out by the manufacturer, stating that the mast complies with the relevant class rules. b) A manufacturer's measurement section duly signed and filled out by the authorised manufacturer. c) An official measurers section duly signed and filled out by an official measurer stating: - that the mast complies with the relevant class rules. - the measurers confirmation that the measurements in section b) are correct.
(ix)	Each mast (near the gooseneck), shall have: a) permanently fixed a unique identifying numbered Authorised Manufacturer Sticker (AMS) issued by ISAF and distributed by IECU. Procedure for AMS fee and fee apportioning shall be similar as stated in Class Rules 2.2.4 (i & ii) for ICF. b) an Authorised Manufacturer Code (AMC), allocated by IECU following approval of each prototype by ISAF, clearly legible and indelibly marked next to the AMS in figures not less than 6mm high. This code may be invalidated if it is established that masts have deviated from the class rules after prototype approval.

Weight

The weight of the mast shall be not less than 5.5kg and the centre of gravity shall be not more than 3500mm below the lower edge of the upper measurement band. If the mast weighs less than 5.5kg but not less than 5.0kg and/or the centre of gravity is more than 3500mm below the lower edge of the upper measurement band, both measured with the halyard removed, lead corrector weight(s), of maximum length 250mm, shall be permanently attached to the outer face of the mast. The weight and the AMS number (see 3.5.4 ix a) shall be permanently marked on the corrector weight(s).

Grandfathering

Masts shall comply with these rules after:

- at fundamental measurements 1 March 2000
- at the Olympic Games 1 March 2000
- at all other events 1 March 2006

Event Authorities may give further allowance.

Boom Builders

(i)	Booms may be built only by manufacturers who have been authorized by the IECU with the approval of ISAF. Authorized Manufacturer status will be granted to applicants based on their technical ability to produce good quality booms in accordance with these rules. Each Authorized Manufacturer will be issued with a unique Authorized Manufacturer Code (AMC) which must be shown on each boom made in accordance with rule 3.6.3 (vii).
(ii)	Prototype measurement is obligatory for all manufacturers to ensure that any prototype boom measures correctly before series production commences. Prototypes shall only be measured by a measurer specifically authorised by ISAF and IECU.
(iii)	The ISAF and or IECU will require specification and samples of materials to check compliance with class rules. A manufacturer shall permit a measurer or class representative, authorised by IECU, to inspect work at any time during production of booms or fittings.

Permitted Boom Materials

(i)

The basic boom section shall be made of wood, laminated wood or aluminium alloy, or any combination of these materials. No other materials as prescribed above shall be used to construct the basic boom section.

(ii)

The boom fittings and Fasteners shall only be made of stainless steel, brass, copper, aluminium alloys, plastic, FRP or any combination thereof. This shall apply for booms fundamental measured after 1 March 1998 and all booms after 1 March 2000.·After 1 March 2000 National Class Unions may give a limited permission to use old carbon booms for national events only. Provided these carbon booms have passed fundamental measurement before 1 March 1998.

Construction and Measurement

(i)	The boom shall comply with the dimensions and requirements specified on the mast and boom measurement diagrams and/or the measurement form.
(ii)	A stop shall be fitted to the boom to prevent the sail being hauled out beyond the inner edge of the measurement band.
(iii)	The boom shall be straight but a permanent set due to distortion of 20mm shall be permitted.
(iv)	The boom shall be fitted to the mast so that they rotate together.
(v)	There shall be a track or groove on the upper side of the boom for the foot bolt rope of the sail.
(vi)	A manufacturer shall issue with each boom a measurement form issued by IECU. This form shall have three sections, i.e. a) An Authorised Manufacturers Declaration (AMD) duly signed and filled out by the manufacturer, stating that the boom complies with the relevant class rules. b) A manufacturers measurement section duly signed and filled out by the authorised manufacturer. c) An official measurers section duly signed and filled out by an official measurer stating: - that the boom complies with the relevant class rules. - the measurers confirmation that the measurements in section b) are correct.
(vii)	Each Boom (near the gooseneck), shall have: a) permanently fixed a unique identifying numbered Authorised Manufacturer Sticker (AMS) issued by ISAF and distributed by IECU. Procedure for AMS fee and fee apportioning shall be similar as stated in Class Rules 2.2.4 (i & ii) for ICF. b) an Authorised Manufacturer Code (AMC), allocated by IECU following approval of each prototype by ISAF, clearly legible and indelibly marked next to the AMS in figures not less than 6mm high. This code may be invalidated if it is established that booms have deviated from the class rules after prototype approval.

Weight

If the weight of the boom, without sheet blocks and shackles, but with securing eyes, kicker (vang) system and its running rigging in their racing position (loose and movable ends fixed vertically), is less than 3.30kg but not less than 3.00kg and/or the centre of gravity is less than 1250mm from the gooseneck end, lead corrector weights shall be fitted to the outside of the profile.

ALL UP WEIGHT

The all up weight is not controlled.