NOTE: Issue No. 3 of the new restrictions cancels and supercedes all previous issues. The object of these revised restrictions is to provide uniform specifications and restrictions for the above class. They are to be read in conjunction with the Plans, Building Instructions and Material List, but over-ride any reccomendations made therein. These restrictions are operative from 1st January, 1990.

1. GENERAL

To compete in "Yvonne 20" Catamaran Class racing, a boat must comply with these restrictions. The construction method has been de-restricted with the use of materials for hulls confined to Foam Sandwich, Balsa Sandwich, Fibreglass and Timber, but still retaining the measurements and weight restrictions as set out in the restrictions and measurement procedures, so that the external appearance of the completed set of hulls falls within the measurement requirements of restrictions.

2. PRINCIPLE DIMENSIONS (All dimensions in millimetres):

(a) Length overall	- 6096 +/-15
(b) Maximum beam	- 2286 +/-13 taken at deck (station 6), excluding
	gunwales
(c) Keel centres	- 1829 +/-13 (New boats)

Note: At the discretion of the measurer, only one hull need be measured. It is suggested that the measurer choose the hull by the toss of a coin.

3. WEIGHT OF HULL (stripped):

350lbs minimum.
Hull shall be dry when weighed and minus spars, centreboard, rudders and sheets. Weight correctors are permitted, they shall be placed against the platecase above or below the bridgedeck floor.

4. TIMBER:

Type of timber is optional, however, the use of balsa wood, other than as a filler in fibreglass sandwich, is not permitted.

5. TIMBER SIZES:

With de-restricted construction method the following are recommended in all wood construction, but may vary in composite construction.

(a) Frames	- 35mm x 13mm (refer Item 7)
(b) Keel	- 38mm x 17mm
(c) Chines	- 38mm x 17mm
(d) Inwales	- 17mm x 17mm
(e) Platecase beams	- Top: 76mm x 38mm Bottom: 38mm x 25mm
(f) Deck beams	- 51mm x 10mm
(g) Cockpit floor rails	- 64mm x 38mm and 32mm x 25mm
(h) Beams 4,6 & 9	- Top and bottom rails: 38mm x 19mm

6. PLYWOOD:

Shall be 3 or 5 ply and be of approved marine grade waterproof quality. Plywood may be replaced by fibreglass foam sandwich, Fibreglass end-grain balsa sandwich or fibreglass. In all plywood construction the following shall apply:

(a) Hulls	- 4mm
(b) Decks	- 4mm
(c) Cockpit floor	- 6mm

The above conditions may include the use of carbon-fibre and/or kevlar.

7. FRAMES:

On frame profile dimensions there is a tolerance of plus or minus 6mm.

8. STERNS:

Thickness aft shall not exceed 48mm including hull skin.

9. GUNWALES (External):

If fitted, shall not exceed 25mm when measured at right angles from the external hull skin.

10. SHEET-HANDLING GEAR:

Maximum extension from hull skin: 38mm excluding deck.

11. CROSS BEAMS:

The term "cross beams" refers to all transverse beams joining the two hulls.
(a) There shall be cross beams at frames 3, 4, 6, 9 and 9 ½ - 330mm aft of frame 9. Frames 4, 6 and 9 shall extend to the inside of the outer skin of each hull.
(b) Cross beams at 4, 6 and 9 shall be "BOX" section. The ply sides at cross beams 4, 6 and 9 shall be 4mm minimum thickness.
(c) Depth of cross beams:

At Frame 4	- 203mm +/-6mm (Main Cross Beam).
At Frame 6	- 191mm +/-6mm (Fwd Cockpit Cross Beam).
At Frame 9	- 153mm +/-6mm (Aft Cockpit Cross Beam).

These dimensions are constant across the width of the boat. Centreplate extensions and weight correctors are not to be included.

12. ROLLED DECKS:

Decks between cross beams 6 and 9 may be rolled from 178mm from the outer hull skin to the cockpit floor.

13. SPRING OF KEEL:

Is measured at the Stem, Stern and at frame positions 1, 2, 3, 7 and 9 as shown on the plan. The dimensions are as follows with a tolerance of +/-6mm from level floor or baseline.
(TO BE CHECKED)
The outside of the inner stem to Frame 1 shall be a true arc of a 966mm radius with pivot point as shown on plan. Tolerance on all above dimensions shal be +/-6mm. For measuring after the hull has been skinned the spring of the keel shall be:
(TO BE CHECKED)

14. HATCHES:

Minimum requirements - 76mm diameter screw-type inspection ports, two in each hull, of which one is to be forward and one aft of the bulkhead Frame 6. Inspection ports may be placed in the bulkheads and must be capable of being made watertught.

15. COCKPIT:

Floor is to be 64mm x 38mm and longitudinal supports 32mm x 25mm. Longitudinals may be placed above or below cockpit floor

16. ANTI-DIVE RAILS:

May be fitted, and if so, they must extend from the bows to Frame 3 and be no lower than 254mm from the deck and project no more than 76mm from the hull.

17. BOW SPREADER:

Shall be of solid timber or extruded aluminium (minimum 2mm wall thickness) and may be shaped to a streamlined section. Maximum thickness shall be 38mm +/-5mm and the maximum width shall be 110mm +/-15mm throughout the length of the bar between the bow bolts. Strop intersection point to be a maximum 190mm +/-15mm above the surface of the spreader bar.

18. RUDDER AND TILLERS:

De-restricted.

19. BRIDGE-DECK:

The forward of the bridge-deck can extend maximum of 609mm from forward edge of Frame 4, and may be wholly or part covered with a 4mm plywood between Frame 4 and Frame 6.

20. CREW:

Racing crew is TWO, including Skipper (Helmsman).

21. TRAPEZE:

May be used, one on either side of the mast, for forward-hand's use only.

22. MAST:

The only restrictions are (in mm):

(a) Length	- 7162 +/-76.
(b) Halyard Heights	- Jib: 5131 to 5232 (from base of mast to bottom of
	hole of jib attachment point). The fitting which is fixed
	to the mast to take the jib shall not extend from the
	mast by more than 50mm.
	- Spinnaker: 6096 to 6198 (from base of mast to
	top of sheave).
(c) Gooseneck Height	- De-restricted.
(d) Spinnaker Pole Fitting	- Height to be maximum of 914 from base of mast
(e) Minimum Weight	- 35lbs. including rigging. Note: Rigging includes
	halyards, trapeze wires, side stays, forestay,
	spreaders, fittings, etc.
(f) Step	- The maximum height of Mast Step is 76 above deck,
	and aft edge of sail track shall be located on the centre
	line of the boat between 2460 and 2565 from the bow
	when the mast is in sailing position.
(g) Maximum Depth	- 177 including sail track.

23. BOOM:

The only restrictions are (in mm):

(a) Length	- 3480 maximum overall including gooseneck and fitting.
(b) Depth	- 105 maximum.

24. SPINNAKER POLE (pre 2004/2005 season):

Maximum length overall including fittings shall be 3567mm, may be timber or aluminium, but must be buoyant.

25. JIB BOOM:

May be used provided the depth does not exceed 76mm.

26. CENTREPLATE:

Shall be made of solid timber, size and shape must fall within the profile shown on the plan with minimum finished thickness 35mm to the underside of the centrecase, but may be shaped as required below this point. At no point below the drawn waterline shall the plate exceed 279mm in the fore and aft measurement when in position, shall not extend more or less then 1473mm +/-152mm tolerance below the underside of the Bridge Deck. Only one centreplate, which shall be stamped by State Measurer, shall be used per sailing series and any alteration or replacement necessitated by damage, to be subject to approval by State Measurer.
Note: The 203mm radius on the leading edge of the centreplate has been de-restricted. The centreplate may be sheathed in fibreglass or carbon-fibre.

27. SAILS:

Are restricted to only one suit at any time (i.e. Main, Jib and Spinnaker). These will be measured when the boat is first measured and if within specification shall be stamped, dated and initialled by the measurer. If, subsequently, anothersail is to be used, this must be passed by the measurer and stamped and initialled. The replaced sail must then be CANCELLED.
Note: Specific restrictions apply to Championship Series.
A CANCELLED sail cannot be again used in class racing without the permission of the Sailing Committee concerned, and without re-measuring by an official measurer.
(a) Sail Marking - Must be in accordance with the I.Y.R.U. rules. The Class emblem for the "Yvonne" is the capital letter "Y" which shall be located above the registration number on each side of the mainsail.
(b) Material Weight (minimum) - Imperial:

Mainsail	- 3.5 UK ozs
Jib	- 4.5 UK ozs
Spinnaker	- 0.75 UK ozs

Note: 1.5 US ozs = 1.92 ozs UK.

28(a). MAINSAIL:

MAST:

There shall be two bands, a minimum of 20mm wide, permanently marked on the mast so as the inner edges are a maximum of 6450mm apart at the farthest point. This measurement shall be taken on a line along the sail track.
These bands shall be as close as possible to square to the sail track and shall be completely around the mast.
The bands shall be either black or white and shall be selected to best contrast the background colour. There shall be no similar marking within 300mm of either measurement band.
The mainsail shall not be adjusted so as to overlap the measurement bands on the mast.

BOOM:

There shall be one band, a minimum of 20mm wide, permanently marked on the boom so as the forward edge is a maximum of 2850mm from the back edge of the mast sailtrack when the boom is in it's normal sailing position. The line of measurement shall be a projection forward of the line of the top of the boom.
The band shall be either black or white and shall be selected to best contrast the background colour. There shall be no similar marking within 300mm of the measurement band.
The mainsail shall not be adjusted so as to overlap the measurement bands on the boom.
There is no restriction on boom length.

MAINSAIL MEASURING:

Sail cloth shall be a minimum of 3.5 UK ounces (2.7 US ounces).
There shall be a minimum of 5 and maximum of 7 mainsail battens.
All battens are to removed during measuring.
Sail cloth shall be pulled just taught enough to remove wrinkles or folds along the line being measured.

With reference to drawing 28.a.1.:
Point B is defined using the measuring template, dimensions of which are shown in drawing 28.a.2. No part of the head of the sail shall extend beyond the edges of this template when point A of the template is positioned over point A of the mainsail.
Point G is defined by folding point A to point I and marking the midpoint.
Point H is defined by folding point G to point I and marking the midpoint.
Point E is defined by folding point A to point G and marking the midpoint.
Point F is defined by folding point E to point G and marking the midpoint.
Point C is defined by folding point A to point E and marking the midpoint.
Point D is defined by folding point C to point E and marking the midpoint.
Point J is defined by folding point K to point I and marking the midpoint.

The girth measurements taken at points D, E, F, G and H are to be taken from (i) the defined point on the leech, to (ii) the luff at it's closest point, and are not to exceed the lengths shown on drawing 28.a.1.
The measurements (i) point A to point I, and (ii) point A to point J, are not to exceed the lengths shown on drawing 28.a.1.
The headboard shall not extend further than 150mm from the front edge of the luff/head intersection point.

28(b). JIB:

Set out basic triangle ABC on flat floor. Mark line DD in the position shown on the diagram, extending the line about 305mm outside the triangle. Lay sail flat on this plan with all wrinkles removed. Peak, Tack and Clew plus all of the foot must lie within the basic triangle ABC.
The maximum width of sail at DD is 1130mm. The luff, leach and foot shall be smooth curves.
BATTENS: Headboards not permitted, battens de-restricted.

28(c). SPINNAKER (added September 2004):

(i) Perimeter of sail not to exceed 19500mm.
(ii) Mid-girth not to exceed 3500mm.
(iii) Base of mast to top of halyard sheave bearing not to exceed 7100mm.
(iv) Front of bows (measured from mid-point between the two bows) to front of pole tack sheave bearing not to exceed 1800mm.
(v) Spinnaker pole may be fixed or retractable.

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Old Mainsail (pre 1997/8 season):

Set out basic triangle ABC on flat floor. Mark lines E, F and G across the triangle at the positions shown on the diagram, extending lines about 305mm outside the triangle. Mark curved lines AC and BC. These shall be a fair curve, and shall meet at A at an angle of 44°. The 102mm measurement on the luff is taken at line F.The 127mm measurement on the foot is taken midway between points B and C.
Lay sail flat on this plan with all wrinkles removed (bolt ropes may need tension to achieve this). The Head Tack, Clew, Leach and Luff must all lie inside curved lines AB, AC and CB.
The luff, leach and foot shall be smooth curves.
BATTENS: Minimum of five and maximum of seven, excluding headboard.

The area must not exceed 175 sq. ft.

(i) Mark out on the floor a triangle of the required measurements, as shown on the diagram, with continuous lines. Any Spinnaker laid on the floor shall, when tensioned sufficiently so that all three sides are tight , be such that all three corners are simultaneously within the above triangle.

(ii) Fold the Spinnaker in halves with both leeches together and the length of the fold shall not protrude outside the triangle at the point of the fold.

(iii) Refold the Spinnaker by placing the head on the centre of the foot and the measurement of the fold shall not protrude outside the triangle at the point of the fold, this measurement to be taken with the foot of the Spinnaker at the base of the triangle.

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