G. Sail

IDNIYRA OFFICIAL SPECIFICATIONS

REVISED MAY 2024
Note: Dimensions are given in inches in the English System (except as noted) and in millimeters (MM) in the metric system.

G. Sail
1. The cloth must be made with high tenacity polyester (dacron) yarns. Sail cloth must be made with either of the following cloth constructions: 6.5 oz. cloth with 220 denier warp and 440 denier fill yarns or 280 grams/square meter cloth with 250 denier warp and 410 denier fill yarns.
2. Luff shall be 14’ (4267 mm) or less. A bolt rope is required.
3. The foot shall be 8’10” or less (2692 mm) or less. A bolt rope is required.
4. Leech shall be 14’3’’ (4343 mm) or less.
5. There shall be three girth measurements taken by folding the sail in quarters according to the procedure specified in G.18

• Top girth measurement 3’3’’ (990.6 mm) or less.
• Middle girth measurement 5’8’’ (1727 mm) or less.
• Bottom girth measurement 7’6’’ (2286 mm) or less.

6. Head of sail.

1. The width of the headboard shall be 4” (101.6mm) or less.
2. The overall dimension of the head of the sail, including bolt rope, shall be 5.5” (139.78 mm) or less.
3. The location of the measurement point at the forward upper corner of the headboard is determined by projecting a straight line parallel to the luff, excluding the luff bolt rope, to the point where it intersects with a line projected from the uppermost point of the headboard and perpendicular to the luff. Refer to diagram G.6.c. below.

7. The sail shall be constructed with four batten pockets. The top edge of the top batten pocket must be a minimum of 27’’ (686 mm) below the top of the headboard. Spacing between battens shall not exceed 36’’ (914 mm) nor be less than 32’’ (813 mm). The top three battens shall be full length, extending from the leech of the sail to within 2’’ (50.8 mm) of the bolt rope. The bottom batten shall not exceed 36’’ (914 mm) in length.

8. Batten pockets shall lie at 90 degrees plus or minus 5 degrees to the leech as defined in G. 17 (Ref G.25a,5, Procedure for measuring a DN sail.)

9. Batten material and structural characteristics are optional. Batten width shall be 2’’ (50.8 mm) maximum.

10. Sail may have one row of reef points which cannot be located less than 18’’ (458mm) from the foot of the sail.

11. A yacht is restricted to the use of two sails in a regatta.

12. Altering the sail characteristics, such as area and camber, during a regatta by means other than the natural flexing of the structural members and positioning the clew grommet on the outhaul bracket are prohibited. This includes reefing. Batten adjustment is excluded.

13. National letter(s), yacht number and the letters “DN” shall be affixed to each side of the sail. Color of the letters and number shall contrast with the sail and be a minimum of 10” (255 mm) high. The letters and numbers shall be one piece, one color, block style letters on all sails made after July 1989.

14. A window in the sail is required. The window may be any shape and placed in several sections.

15. A steel cable, at least 3/64” (1.2 mm) in diameter may be attached to the headboard, running inside the luff to a point outside the sail at the tack. Lower end of the cable shall form a loop which must be secured to the tack pin on boom when under sail. Distance from top of headboard to center of 1/4’’ (6.3 mm) bolt inserted in the loop shall not exceed 14’ (4267 mm) with cable straight and under 10 lbs. (4.6 kg) of tension.

16. Sail shall not extend aft of the forward edge of the 1/2’’ (12 mm) boom stripe which is located 8’10’’ (2692 mm) from the forward edge of mast slot.

17. The leech, defined as the straight line between the forward upper corner of the headboard and the point where the leech intersects the foot at the clew, excluding the foot bolt rope, shall be measured with the sail free of battens and with 5 lbs. (2.3 kg) of tension. (Ref. G.6.c. and diagrams Upper Forward Corner of Headboard, G.6.c. and Clew, G.17.)

18. The three girth measurements shall be measured with battens removed and such tension as is required to remove wrinkles.

1. The middle girth is measured between the mid points of the luff, excluding the bolt rope, and leech at the trailing edge. The mid point of the luff is found by folding the sail so the forward upper corner of the headboard lines up with the intersection of the luff and foot at the tack, excluding the bolt rope(s). The mid point of the leech at the trailing edge is found by folding the sail so the forward upper corner of the headboard lines up with the intersection of the leech and foot at the clew, excluding the bolt rope(s). (Ref. G 5 and diagrams Upper Forward Corner of Headboard, G.6.c; Clew, G17; and Tack, G.24.)
2. The top girth is measured between the quarter points of the luff, excluding the bolt rope, and leech at the trailing edge. The top quarter girth point on the luff is found by folding the sail so the forward upper corner of the headboard lines up with the mid point on the luff, excluding the bolt rope. The top quarter girth point on the leech is found by folding the sail so the forward upper corner of the headboard lines up with the mid point on the leech at the trailing edge. (Ref G.5 and diagrams Upper Forward Corner of Headboard, G.6.c.)
3. The bottom girth is measured between the quarter points of the luff, excluding the bolt rope, and leech at the trailing edge. The bottom quarter girth point on the luff is found by folding the sail so the tack at the intersection of the luff and foot, excluding the bolt rope(s),lines up with the luff mid point. The bottom quarter girth point on the leech is found by folding the sail so the clew at the intersection of leech and foot, excluding the bolt rope, lines up with the mid point on the leech at the trailing edge. (Ref. G. 5, and diagrams Upper Forward Corner of Headboard, G.6.c.; Tack, G.24; and Clew, G.17.)

19. Sails shall not be colored red or orange.

20. The profile of the sail along the leech at the trailing edge shall be such that the maximum inward curve of the edge of the leech shall not exceed ¾” from a line drawn from the back of the headboard to the outer end of the second batten pocket from the top; and from a line drawn from the outer end of the top batten pocket to the outer end of the third batten pocket from the top.

21. The profile of the leech at the trailing edge above the top batten pocket shall be such that no part of the sail extends outward more than 1/4” from a line drawn from the back of the headboard to the outer end of the top batten pocket.

22. The luff and the foot of the sail must have a boltrope that is inside the boltrope tunnel of the mast and boom while sailing, except in the area within 12 inches of the tack.

23. The tack of the sail must be fixed to a fitting at the forward end of the boom.

24. The luff, defined as a line between the forward upper corner of the headboard and the intersection of the foot and luff at the tack, excluding boltropes, shall be measured with the sail free of battens and under 5 lbs. (2.3 kg) of tension. (Ref. diagram Upper Forward Corner of Headboard, G.6.c. and Tack, G.24.)

25. Procedure for measuring a DN sail.

1. Preparing the sail for measuring:
   • 1. The sail shall be free of the mast and boom.
   • 2. Battens should be removed.
   • 3. Lay the sail on a hard surface (table, floor, or ice sailing surface).
   • 4. Measure each specified dimension one-at-a-time with tension applied only across the line of measurement as is sufficient to remove wrinkles except as specified in G.17, G.24, and G.25c.1.
   • 5. Use the following points of measurement when measuring location of battens and batten pockets and pocket angles.
     • aa. Locate the straight line leech by stretching a string or small diameter rope from the forward upper corner of the headboard to the clew, excluding the bolt rope. (ref. G.6.c. and G.17)
     • bb. The top edge of a batten pocket is located along the top of the inside width of the pocket. The centerline of the batten pocket is located in the center of the inside width of the pocket.
   • 6. Use the location of the Forward Upper Corner of the Headboard (ref. G.6.c.) as the measurement point when folding to measure the girths (ref. G.18)
2. To determine the location of the top batten pocket and spacing between battens (ref. G. 7):
   • 1. In G.7 the measuring point on the top of the headboard is located at the forward upper corner of the headboard (ref. G.6.c.). All points along the top edge of the pocket must comply with the 27” (686 mm) minimum dimension from the head (ref. 25.a.5.bb.)
   • 2. The spacing between the battens is measured between the centerline of the batten pockets where the centerline intersects with the straight line leech (ref G.25.a.5.aa)
3. To determine the angle of the battens pockets (ref. G.8.):
   • 1. Pin the head, tack and clew in place on the hard surface while applying tension along the luff, foot, and straight line leech to remove wrinkles. The leech at the trailing edge should not lift away from the hard surface.
   • 2. Measure the angle between the straight line leech and the top edge of the batten pocket. (ref. G.25.a.5.aa and bb).
   • 3. Measure one-pocket-at-a-time.
   • 4. Place the base of a protractor along the straight line leech, centered at the top edge of the batten pocket (ref. G25.a.5.bb) and facing the luff.
   • 5. Read the angle at the top edge of the pocket. (ref. G.25.a.5.bb).