OFFICIAL SPECIFICATIONS

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Revision May.2013

NOTE: Dimensions are given in inches in the English System (except as noted) and in millimeters (mm) in the metric system.


Fuselage | Runner Plank | Mast | Boom | Runners | Runner Base a. Cut | Sail | Rigging | Fittings | Interpretations |

A. Fuselaqe
English Metric
Max Min Max Min
1.Length overall: 147 141 3733.0 3582.0
2.Beam: 21-1/2 17-1/2 546.0 445.0
3.Thickness of decks and cockpit floor:
1/4 0.118 6.3 3.0
4.Thickness of bottom: 1/4 0.118 6.3 3.0
5.Sides and bulkhead at front of cockpit:
1 5/8 25.4 15.9
6.Intersection of seat back and floor to pivot pin of steering runner:
110-1/4 98-1/4 2800.0 2496.0
7.Distance from bow to front of cockpit:
66 54 1676.0 1372.0
8.Stem block length is optional.
9.Stem width at bow: 3-3/4 2 95.0 51.0
10.Stern block length is optional.
11.Stern width at stern: 4 1-1/4 101.0 31.0

12.Seat backs shall be raked aft at an angle of 45 degrees plus or minus 10 degrees. They may be hinged for access to stowage compartment.

13.Seat back shall be flat, measuring 11″ (280. mm) in length at the center line, no maximum height, the crown on top of seat must be a minimum of 2″ (50.8 mm) radius with minimum seat width 4″.

14.Depth of side panel at each fuselage station shall not be less than heights in the following table:

Layout of Side Panel Minimum Side Heights
Position along side panel starting at bow Side panel height
Inches MM Inches MM
2 51 2-9/16 65
12 305 3-7/8 98
24 610 5-1/16 129
36 914 6-1/16 154
48 1220 6-7/16 164
60 1524 6-5/8 168
72 1829 6-5/8 168
84 2134 6-1/2 165
96 2438 6-3/16 157
108 2743 5-9/16 141
120 3048 4-5/8 117
132 3353 3-3/8 86
Last station: 2 inches 2 51
(51mm) from the stern.

15.a.Bottom heights of side panels shall not exceed a maximum of 1″ (25.4 mm) above zero line and/or a maximum of 1/2″ (12.7 mm) below zero line. Zero line shall be established by a straight line tangent to stem and stern on bottom.

b.Maximum height of side panels above zero line may be 8-1/2″ (215.9 mm) including deck and bottom covering. All heights of side panels shall be proportional to height as shown in “Layout of Side Panel”. The top edge of the side panel may not be concave at any point along its length.

16.Hull cross sections must be rectangular from a point 6″(153. mm) from the bow to a point 6″ (153. mm) from the stern. A maximum 1/4″ (6.3 mm) radius is allowed on the outside top corner of the fuselage where the deck and side panel intersect. Concavities in the deck are not permitted.

17.Cockpit floor shall be installed as shown in plans,cockpit floor skin must be on top of listings. The total thickness of the cockpit floor including the bottom skin and cockpit floor skin must be a minimum of 5/8″ (15.9mm). A minimum of 2 knees must be installed.

18.Structural members such as longerons, stringers, knees, listings, bulkheads, bottom, deck, etc. may be added. Deck may not protrude more than 3″ (76mm) into the cockpit from the bulkhead at the front of the cockpit.

19.Design of the internal structure of the fuselage is optional.

20.Grab rails may be installed on the inside and/or outside vertical surface of the side panels. They may not extend beyond 8″ (203. mm) from either end of cockpit. Rails shall not exceed 1″ (25.4 mm) in depth or width. Rails are exempted from fuselage measurements.

21.Steering post and chock may be inclined in the vertical plane of symmetry.

22.Steering shall be accomplished by means of a tiller. Tiller may be of any length or shape but may not be more than 8 inches (203 mm) wide. Material is optional.

23.Either steering rods, cables, or a single push pull link shall be used and shall be positioned beneath the fuselage as shown on the Official Plans.

24.Ballast, if used, shall be permanently installed.

25.Fuselage shall be constructed of wood only, except as provided in specification A.31.(Sitka spruce is most popular). Fiberglass may be added for reinforcement only. See Interpretations-General.

26.Sides shall not be hollow.

27.Minimum weight shall be 46 lbs. (21 kg) with all hardware, blocks, and tiller.

28.A full bulkhead must be installed at the front of cockpit.

29.Horizontal distance from the Bow to the pivot point or the front runner:

English Metric
Max Min Max Min
7 3 177,8 76,2

30.National letter and Sail number shall be affixed to each side of the fuselage below the mast stepping point. Color shall contrast with the fuselage and each letter and number shall be a minimum of 5.5 inches (140 mm) high and 0.7874 inches (20 mm) wide.

31.Foam is an allowed material for the internal construction of the fuselage, reference A.19

See Fuselage interpretations at the end of the Specifications.

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B. Runner Plank
English Metric
Max Min Max Min
1.Length overall (including hardware except pivot bolt) (See Interpretations at end of specs)
96 94 2438 2388
2.Width at centerline 7-1/2 6-1/2 190.5 165.2
3.Thickness at centerline 1-5/8 1-1/8 41.2 28.6
4.Width at ends 7-1/2 5-1/2 190.5 139.5
5.Thickness at ends 1-5/8 1 41.2 25.5

6.Cross section is optional

7.Runner plank shall be constructed of wood. Number of laminations is optional. Fiberglass may be added. See Interpretations-General.

8.The underside of the runner plank shall be higher at the centerline than the underside of the outside ends. The profile of the plank lamination must assume a reasonable fair and continuous curve. Cutouts or hollow depressions are not permitted.

9.The runner plank, including all hardware and pivot bolts, may not weight less than 20 lbs. (9.0 kg.).

See Runner Plank Interpretations at end of Specifications.

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C. Mast
English Metric
Max Min Max Min
1.Dimensions:
a.Length overall (including hardware)
192 186 4876.8 4724.4
b.The maximum fore and aft dimensions, excluding hardware:
4 101.6
c.The minimum fore and aft dimensions, measured from full section above boom jaw area to a point located 127-1/2″ (3238.5 mm) above the mast base:
3-1/2 88.9
d.The minimum fore and aft dimensions, measured above a point located 127-1/2″ (3238.5 mm) above the mast base:
2 50.8
e.The maximum side to side dimension, excluding hardware:
2-1/2 63.5
f.The minimum side to side dimension, below a point located 127-1/2″ (3238.5 mm) above the mast base:
2 50.8
g.The minimum side to side dimension, measured above a point located 127-1/2″ (3238.5 mm) above the mast base:
1-1/8 28.6
h.The minimum depth of the boltrope tunnel from the outside trailing edge:
3/8 9.5

2.Materials: Aluminum; wood; carbon or glass fiber; adhesives; foam; fairing and finishing materials.

3.Other Specifications:

a.Only one boltrope tunnel is permitted. The bolt rope tunnel shall be substantially straight with the mast relaxed. Track is prohibited.

b.Cross section profiles are optional. Mast may be solid or hollow.

c.A halyard must be installed. An internal halyard is permitted.

d.Devices which prevent or hinder movement of the boom on the mast are prohibited.

e.The bottom of the mast must be fitted with a socket that will pivot freely on the mast step deck ball.

f.The mast, without stays but complete with hardware and halyard used while sailing, may weigh no less than 15 lbs. (6.80 kg). Aluminum masts produced from a die existing prior to July 1, 1996 may weigh less than 15 lbs. (6.80 kg).

g.When supported at one point in an approximate horizontal position, the mast, without stays but complete with hardware and halyard in sailing position, must balance at a point a minimum of 84 inches (2133.6 mm) from the mast base.

h.A removable internal reinforcement of allowable materials is allowed. This reinforcement may not be altered, turned or removed during a regatta.

See Mast Interpretations at end of the Specifications.

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D. Boom
English Metric
Max Min Max Min
1.Length (from mast) 108 Opt 2743 Opt.
2.Depth (from outhaul bracket to 12″, 305mm, from mast)
3 2-1/2 76.2 63.6
3.Thickness (from outhaul bracket to 12″, 305mm from mast)
1-25/32 1-1/4 45.25 31.8

4.Only one boltrope tunnel is permitted. The boltrope tunnel shall be substantially straight with boom relaxed. An aluminum boltrope tube is allowed. It must weigh less than three ounces per foot (280 grams/meter). The internal diameter must be at least 3/8″ (9.5mm). The cross section of the tube is optional.

5.Cross section profile is optional. Boom may be hollow.

6.Boom jaws are optional. Devices which prevent or hinder movement of the boom on the mast are prohibited except for check wire.

7.A 1/2″ (12. mm) wide stripe shall be painted around the boom in contrasting color. Stripe shall be perpendicular to sail tunnel. Forward edge of the stripe shall be 8′ 10″ (2692 mm) or less from forward inner surface of mast sail slot projected fairly.

8.Boom shall be constructed of wood or aluminum. Fiberglass may be added for reinforcement only.

See Boom Interpretations at the end of the Specifications.

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E. Runners
English Metric
Max Min Max Min
1.Steel plate type (steel body with stiffening elements)
a.Plate thickness 0.27 0.23 6.8 5.9
b.Plate length 30.0 26.0 762 660.4
c.Plate heights of at least that part contained in chock. (Note: allow for sharpening.)
5.0 3.74 127 95.
d.Thickness (contained by chock):
1-1/32 31/32 26.1 24.7

e.Length and height of runner assembly (plate plus stiffening elements) shall not exceed those allowed for the steel plate. Material, location and cross section of stiffening elements are optional, provided Specifications E-3 and E-4 are not violated.

f.Method of attaching stiffening elements is optional.

g.Type of steel plate is optional.

2.Wood type (wood body with attached steel angle, “T” section, or steel plate). This means commercially available section. Technical Committee will rule against any special fabrications.

English Metric
Max Min Max Min
a.Thickness of body: 1-1/32 7/8 26.1 22.3
b.Length 36 30 914 763.
c.Height of at least that part contained by the chock:
5 4 127 101.7
d.Thickness (contained by chock):
1-1/32 31/32 26.1 24.7

e.Body shall be made of wood. Fiberglass may be added. Plate may be attached by bolts, or epoxy or both.

f.The steel sections allowed are American Standard 3/4″ (19.1 mm) x 3/4″ (19.1 mm) x 1/8″ (3.3 mm) “angle” and 1″ (25.4 mm) x 1″ (25.4 mm) x 3/16″ (4.8 mm) or 1/4″ (6.4 mm) “T”. Equivalent metric measure (DIN) sections may be used provided the dimensions are within 20% of those listed.

English Metric (DIN Sections)
Max Min Max Min
Angle Type:
Profile Width 3/4 22.8 15.3
Thickness 1/8 3.8 2.6
T Type :
Profile Width 1 30.4 20.4
Thickness 1/4 3/16 7.6 3.9

g.The “T” section must not be reduced to less than 75% of its original height by sharpening.

h.Wood type with steel insert.

Insert plate dimensions:

English Metric
Max Min Max Min
Width: 3 2 76.2 50.8
Thickness: 0. 270 0.1875 6.8 4.8
Max. width exposed below wood runner body:
1-1/2 38.1

i.The body of a wood runner may be tapered below the minimum 7/8″ (22.3 mm) thickness at a point 6″ (152 mm) from the front end of the runner body. The body shall not be less than 1/4″ thick at the front end.

3.Profile of runner is optional with the exception that front ends of all runners shall have a 5/8″ (16 mm) radius or larger.

4.Runner stiffening elements shall not project laterally more than 3″ (76.2 mm) from runner edge. If runner-stiffening elements are used as a weight-bearing component (in contact with ice or snow), they must be totally located within the runner cut specifications (F2).

5.Steering runner shall be equipped with a strong and effective parking brake at all times.

6.Weight of any individual runner shall not exceed 17 lbs. (7.7 kg).

7.Method of attaching runner to chock and chock to plank shall be accomplished as shown in plans.

8.Methods of providing relative movement of runner with respect to chock shall be as shown in plans.

9.The leading edge of the runner steel is that portion of the edge forward of the sharpened ice contact edge and higher than ¾” (19 mm) above the ice, measured with the runner in normal sailing position. The sharpened ice contact edge of the runner steel is along the entire bottom edge and extends forward and upward along the edge of the steel to a point not exceeding ¾” (19 mm) above the ice, measured with the runner in normal sailing position. The leading edge must be rounded with no sharp angle point and shall be faired to the sides of the steel as allowed in E.12. Replace by (Nat. Sec. Meeting 2014, Riga): The leading edge must be rounded to an edge radius of not less than 1/16” (1.6 mm) and shall be faired to the side of the steel as allowed in E.12. The sharpened ice contact edge may be rounded or sharpened to an included angle of not less than 75 degrees. The camber (crown) and shape of the sharpened ice contact edge is optional. Along the sharpened ice contact edge, the rounded edge or the sharpened angle is allowed to be faired to the sides of the steel providing the thickness of the steel of plate, insert style or T runners is not reduced below the allowed minimum. (ref. E.1.a., E.2.f., E.2.h).

10.Each yacht shall be restricted to the use of nine runners during a regatta.

11.A maximum of four holes, which are not structurally required, may be drilled in each runner. Holes shall not exceed 1/2″(12.7mm) diameter.

12.Along the leading edge of the steel (ref. E.9.), the minimum allowed steel thickness of plate, insert style, and T runners must be reached within .394”’ (10 mm) measured from the normal tangents of the leading edge (does not apply to ‘angle’ type runners.)

See Runner Interpretations at the end of the Specifications.

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F. Runner Base and Cut (Track)
1.Longitudinal distance from pivot axis of steering runner to pivot axis of aft runner:
English Metric
Max Min Max Min
103 97 2616 2464
2.Lateral distance between aft runner edges below pivot axis:
(To be measured with skipper in cockpit in sailing trim)
95 Opt 2413 Opt.

See Runner Base and Cut Interpretations at the end of the Specifications.

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G. Sail

1.The sail cloth must be made with high tenacity polyester (Dacron) yarns. Sail cloth must be 6.5 ounce/square yard (280 gm/square meter) and made with one of the following constructions:

warp(denier)
fill(denier)
150
440
150
450
250
440
180
440

2.Hoist shall be 14′ (4267 mm) or less.

3.Foot shall be 8’10” (2692 mm) or less.

4.Leech shall be 14’3″ (4343 mm) or less.

5.There shall be three girth measurements excluding boltrope to be determined by folding the sail in quarters. 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.The width of the headboard shall be 4″ (101.6 mm) or less. The overall dimension of the head of the sail, including boltrope, shall be 5-1/2″ (139.78 mm) or less. The sail must have a boltrope.

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.

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″ (458 mm) 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 number of “DN” 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.

English Metric
Area (sq. in. and sq. cm.) Max Min Max Min
1000 100 6452 645

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 leach, defined as the line between the forward upper corner of the headboard and the intersection of the foot and the leach at the clew, shall be measured with the sail free of battens and under 5 lbs. (2.3 kg) of tension.

18.The girth (distance between the luff midpoint and the leech midpoint excluding boltrope) shall be measured with the battens removed and such tension as is required to remove wrinkles. Midpoints are found by folding the sail so holes line up and marking the fold.

19.Sails shall not be colored red or orange.

20.The profile of the sail along the leach shall be such that the maximum inward curve of the edge of the leach shall not exceed 3/4″ 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 above the top batten 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 hoist, 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.

See Sail Interpretations at the end of the Specifications.

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H. Rigging

1.Framing stays are prohibited. Any cable not shown in the plans is prohibited.

2.All stays shall be steel cable and shall be 0.118″ (3 mm) or greater in diameter.

3.Halyard shall be steel cable and shall be 3/32″ (2.4 mm) or greater in diameter.

4.Bobstay shall be installed and fitted to the bow tang forward and anchored at its after end on the stern block or immediately in front of the runner plank.

5.Tubes and other means of rigid adjustment of stay lengths are permissible.

6.Devices which adjust stay lengths while yacht is underway are prohibited.

7.Means for rigid adjustment of mast step location are permissible.

8.Means for adjustment of mast step location while yacht is underway are prohibited.

9.Mast step shall be rigidly mounted on the deck of the fuselage.

10.Mast step shall permit free orientation of mast.

11.Horizontal distance from mast step pivoting point (center of ball) to pivot axis of steering runner:

English Metric
Max Min Max Min
41 35 1041 890
12.Horizontal distance from pivot axis of steering runner to pivot axis of steering post:
50 44 1270 1118
13.Distance from lower mast hound bolt (pivot bolt located in front of mast) to base of mast:
139-1/2 127-1/2 3543 3239

14.Six sheet blocks shall be installed.

15.Four sheet blocks shall be installed aft of the rear limit of the cockpit floor: two on the boom and two on the deck. None of these blocks may incorporate a one-way feature. The blocks on the fuselage must be fastened in a manner such that anything penetrating the deck may only be performing the function of fastening, and no other function.

16.One sheet block shall be located forward on the boom within 1′ (304 mm) of the mast. This block may incorporate a one-way feature.

17.One sheet block shall be installed on the tiller post. This block may incorporate a one-way feature.

18.The sheet must be attached to the boom and pass through all blocks as shown in plans.

19.Blocks must be individual and have fixed positions on fuselage and boom.

20.Sheet may run inside the boom between the forward block and the 2nd block.

21.The distance from the center of the runner plank to the base/foot of the side stay on the end of the plank must be

English Metric
Max Min Max Min
43.07 1094

22.The components of the mast hound may affect the free orientation of the mast by either forcing mast rotation or limiting mast rotation.

See Rigging Interpretations at the end of the Specifications.

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I. Fittings

 

1.Diameter of the sheaves of the sheet blocks shall not exceed 4″ (101.6 mm).

2.Two of the six required blocks may incorporate a one-way feature.

3.Steering chock may incorporate a shock-absorbing feature.

4.Hardware need not conform to plans as long as specifications are not violated and hardware performs the same function that the plan item performs.

5.Side Chock

English Metric
Max Min Max Min
a. Width of runner slot at the smallest dimension where the chocks come in contact with the runner’s side or stiffening element:
1-3/32 31/32 27.7 24.7
b.Depth of chock: 3-1/2 2-7/8 88.9 73.1
c.Length of chock 9 6-3/4 228 172
d.Width of chock 4-3/4 121
6.Mast Step – Height of pivoting point (center of ball) above deck.
1-5/8 1-1/8 41 28.6

7.Location of Halyard catch on mast is optional.

8.Halyard must be capable of lowering and raising the sail with yacht in upright position.

9.Additional fittings to secure halyard to mast are permissible.

10.Only one mast, boom, fuselage, and runner plank may be used for an entire regatta, unless broken beyond reasonable repair (as interpreted by the Race Committee).

11.An adjustable footrest may be used.

12.A device may be placed in the back of the chock to prevent the front of the runner from tipping downwards. The device may not contact the runner when all three runners are on the ice.

13.The side chock and the steering chock shall be made of steel, stainless steel or aluminum.

14.Bow Tang

English Metric
Max Min Max Min
Width: 3 3/4 95.3
Horizontal distance from the pivot axis of the steering runner to the aftermost end of the bow tang: 8 203.2
Height above a horizontal line extending forward from the deck at a point 2″ (50.8 mm) behind the bow: 3 76.2

15.Runner Plank Mounting Hardware

a.The runner plank mounting system shall not extend more than 4″ (101.6 mm) outside of the side panel of the fuselage.

b.The runner plank mounting system shall be located in an area that does not exceed 30″ in the fore and aft dimension.

16.Bobstay Strut, incl. Mounting Hardware

English Metric
Max Min Max Min
a. Height (from bottom skin of fuselage): 3 76.2
b. Length: 6 152.4
c. Width: 4 101.6

17.Mast Step Mounting Hardware

English Metric
Max Min Max Min
a. Length: 9 228.6
b. Width: 3 76.2

See Fitting Interpretations in the following section.

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Interpretations of the Official Specifications by theTechnical Committee, revised Jan. 2012

General:
11/23/87: Material – Kevlar cloth may not be used in DN construction.

11/24/87: All DN racing equipment must be in accordance with the DN specifications. Whether or not he reveals the structural components of his equipment, the competitor is responsible for making sure his equipment is in compliance with the DN specifications.

3/18/89: Specification A.25. specifies wood in the fuselage with fiberglass added for reinforcement only. Carbon fibers and other materials are not allowed. Specification B.7. specifies wood in the runner plank and fiberglass may be added . Carbon fibers and other materials are not allowed. Specification D.8. specifies the boom will be of wood or aluminum. Carbon fibers and other materials are not allowed.

A. Fuselage

11/24/56: Members (such as fiberglass, stringers, knees and longer stem blocks), may be added after the specifications have been complied with and providing the addition does not exceed the specifications.

11/10/73: Sides must be solid wood.

9/23/82: Fiberglass may be used between laminations of the side panels for reinforcing.

10/17/83: With respect to the hull side profile: the term “proportional” will be defined as a “smooth curve” without reversing the line abruptly. Concave sections will not be allowed.

3/18/89: The tiller post must be located forward of the bulkhead at the front of the cockpit. The tiller must be attached to the post at a point above the level of the deck. The sheet block that is installed on the tiller post (Specification H.17) must be attached to the tiller post at a point higher than the point of attachment of the tiller

3/26/89: Definition of deck as used in A.18: the deck is the covering on the top of the fuselage in the areas foreword and aft of the cockpit. The deck extends uninterrupted from the outside of the side panel on one side to the outside of the side panel on the other side.

4/15/91: In A.14, the depth of the side panels does not include the deck and bottom.

7/01/92: The bulkhead at the front of the cockpit must be solid wood and may not be hollow.

7/01/92: To comply with A.9, the forward most part of the stem or a portion of the stem if it is vertical, must comply with the minimum and maximum dimensions allowed.

12/15/2011: Rigging and fittings are not part of the integral structure or reinforcement of the fuselage and may be attached to the fuselage by mechanical fastenings and/or adhesives. The materials allowed in the rigging and fittings attached to the fuselage are optional providing they comply with the Specifications in sections H. and I. and the Interpretations in sections General, H., and I. The dimension and location of the rigging and fittings must comply with the Specifications in Sections A., H., and I. and the Interpretations in sections General, A., H., and I.

12/01/2012: In the side panels it is not allowed to use engineered or composite materials formed by binding particles or loose fibers of wood and fiberglass.

02/15/2013: The bow tang should not be included when measuring the length of the fuselage, specification A.1., and the distance from the bow to the front of the cockpit, specification A.7.

B. Runner plank
1/30/88: The overall length of the runner plank (including hardware except pivot bolt) is measured in a straight line from end to end without the skipper in the cockpit.

11/14/88: Gull wing runner plank: In the profile curve of the runner plank lamination, the curve must not reverse direction and in an unloaded condition no part of the curve may be lower than the ends.

7/01/92: The interpretation dated 1/30/88 is changed to read: The overall length of the runner plank (including hardware except pivot bolt) is measured in a straight line from end to end with the runner plank separate from the fuselage.

11/30/98: The runner plank must be constructed of wood and meet all specifications before the application of external reinforcement. Internal fiberglass reinforcement is not allowed. Foam, honeycomb, and other non-wood core materials are not allowed.

10/6/2011 – Amend 11/30/98 as follows: The runner plank must be constructed of wood and meet all minimum dimensions in specifications B.1., 2., 3., 4., 5. before the application of external reinforcement and coatings; and meet all the maximum dimensions in specifications B. 1., 2., 3., 4., 5. after the application of any external reinforcement and coatings. Internal fiberglass reinforcement is not allowed. Foam, honeycomb, and other non-wood core materials are not allowed.

C. Mast
10/17/83: It is allowed to use a mast which is reinforced with carbon fibers from the inside as well as the outside.

10/17/83: It is allowed to reinforce an aluminum mast with a piece of wood from the inside.

7/01/96: Masts built prior to July 1, 1996, shall be considered legal if they meet prior specifications.

11/30/98: The minimum weight and balance point specifications (C.3.g and C.3.h) must be met with and without any removable internal reinforcement.

11/30/98: The mast must be one piece when used in a regatta.

02/15/2013: In specifications C.3.f. and C.3.g., the term “stays” includes all components and devices used to connect the cables to the mast hound at the height of the lower mast hound bolt, reference specification H.13., All components and devices used to connect the cables to the mast hound at the height of the lower mast hound bolt must be removed from the mast when determining the weight, C.3.f., and the balance point, C.3.g.

D. Boom
01/01/79: The boom jaw may not have a projection on the bearing surface that will fit into the mast slot and thereby affect the rotation of the mast.

E. Runners
1974: It is not allowed to taper or thin the 1/4″ (6.35 mm) thick steel plate runners below the minimum allowed thickness toward the sharpened ice contact edge.

1974: A slot may be machined on the top of allowed “T” sections to facilitate mounting to wood body. Hard weld may be applied to the ice contact edge of allowed “T” sections.

1974: Runner “T” sections may not be altered by welding a bead in the corners.

1977: It is legal to change runners from a light set (6lbs) each to a heavy set of (17lbs) each during a regatta and not be in conflict with the change of ballast.

10/17/83: It is permissible to reinforce wood runner bodies (of regulated thickness) with materials like carbons, aluminum, tin, and similar materials. No Kevlar.

11/23/87: Specifications for the thickness of “T” sections and for insert steel are not the same.

11/23/87: Internal reinforcement of the wooden runner body: The use of threaded rod or bolts to attach “T” iron to the wooden body with the rod extending up to the top of the wood body is a well accepted method of constructing these runners. The wood body of insert runners must meet all the requirements of Section E of the Specifications.

3/18/89: The thickness of the steel plate in insert runners may not be reduced below the minimum thickness of .1875″ except as permitted in specification E.9.

3/18/89: Specification E.2.h. establishes the maximum thickness of the steel plate in insert runners at .27 inches. Therefore, the absolute maximum thickness is .270″ and plate in the thickness range .271″ through .279 is not allowed.

11/14/89: Wood or metal stiffeners may be added to insert runners (as in E.1.e. for plate runners) as long as the minimum wood body meets the dimensions in E.2.a. and the stiffener is outside the wood body. No wood or metal stiffener may come between the insert plate and the slot on the wood body. No metal stiffening is allowed inside the main wood body.

7/1/92: The specifications do not prohibit the changing of the runner stiffening elements during a regatta. However, when the stiffening element is changed, the runner is then counted as a new runner in total count of the nine runners allowed.

7/1/92: Commercially available T, angle, or plate is manufactured in a quantity to be sold to people who want to purchase it. If the T, angle or plate is made only in small quantities for a few people, it is a special fabrication and not allowed to be used. A modification of a commercially available T, angle, or plate by procedures such as surface grinding, milling, bending or flattening is allowed.

11/30/98: The body of a wood body runner must be constructed of wood and adhesive only. No internal reinforcement is allowed except for threaded rod, or bolts, or screws used to attach the steel to the body. The wood body must meet all specifications before the application of external reinforcement. Reinforcement between the blade and body (inside the slot) on insert runners is considered to be outside the wood body and is allowed.

2/10/07: Measuring spec. E.2.h: A simple measuring gauge may be used to measure the amount of exposed steel on insert runners. The gauge should have a slot width at the minimum wood body thickness (7/8″ or 22.3 mm) and depth at the maximum allowed exposure (1-1/2″ or 38.12 mm). This gauge is used as shown below to measure exposed steel. The top of the gauge should touch the bottom of the runner body. The edge of the steel may touch the bottom of the slot, or there may be a gap between the edge of the steel and the gauge. If the edge of the steel is touching the bottom of the slot and both top edges do not touch the bottom of the runner body, then the exposed steel is greater than the maximum allowed. Notes: Because it is impossible to determine the thickness of any reinforcement on the bottom of the runner body, the gauge should be used to measure to the outside of the reinforcement. This gauge should not be used on the front 6″ (152 mm) of the runner (where Spec E.12 allows the body thickness to be reduced below 7/8″). Allowance should be made for small imperfections (porosity, damage, etc) on the bottom surface of the runner body.

1/15/2010: The reinforcement bar or stiffening element that is associated with the “Kent” style chock is part of the runner and must meet all requirements of a runner stiffener, Reference Specifications E.1.e; E.1.f; E.4; Interpretations B. Runner Plank, 1/15/2010; E. Runners, 11/14/89, 7/1/92, 1/15/2010, and I. Fittings, 1/15/2010.

1/15/2010: All runner stiffening elements are considered part of the runner and are included in the runner weight. Reference specification E.6

1/15/2010: The specification making optional the method of attachment of stiffening elements to plate runners, Specification, E.1.f. also applies to the method of attachment of stiffening elements in wood body runners. Attachment is defined as a physical connection that firmly adheres the stiffening element to the runner such that when the chock pivot bolt is removed the stiffening element remains physically connected to the runner. Reference Interpretation 7/1/92.

1/15/2010: At all times while in use the bar or stiffening element that is associated with the “Kent” style chock must be attached to the runner. Any movement of the bar or stiffening element shall be independent of and not controlled by the movement of the chock pivot bolt.

4/14/2010: In Specification E.9. the last sentence states that it is not allowed to taper or thin the ¼” (6.35mm) thick steel plate runner below the minimum allowed thickness toward the sharpened ice contact edge. Therefore the interpretation dated 1974 that repeats the language of E.9. is removed from the interpretations.

4/14/2010: In a previous 1974 interpretation the second sentence referring to hard weld on the ice contact edge of allowed “T” sections is deleted. This interpretation now reads: A slot may be machined on the top of allowed “T” sections to facilitate mounting to wood body.

4/14/2010: Hard weld may be applied to the ice contact edge of all runners.

4/14/2010: A previous 1974 interpretation that disallowed the welding of a bead in the corner of “T” runners is deleted and replaced with a new interpretation: Runner “T’ sections may not be formed by welding and may not be altered by welding a bead in the corners.

4/14/2010: The steel angle section allowed in E.2.f need not be mounted symmetrically on the wood body but must be mounted to the wood body in a manner that the ice contact edge corresponds to the apex of the included angle of the steel section.

3/18/89, amended 10-1-2010: The thickness of the steel plate in insert runners may not be reduced below the minimum thickness of .1875” except as permitted in specification E.12.

10/1/2010: The interpretation dated 4/14/2010 has been clarified in the rewording of specification E9, effective 10/1/2010. DELETE 4/14/2010 which read: In specification E.9. the last sentence states that it is not allowed to taper or thin the ¼” (6.35mm) thick steel plate runner below the minimum allowed thickness toward the sharpened ice contact edge. Therefore the interpretation dated 1974 that repeats the language of E.9. is removed the interpretations.

10/1/2010: Diagram 19 mm Dimension (attached to be published in Runner Tracks and in the yearbook).

DN_Runner_Diagram_19_mm_Dimension

12/01/2012: The interpretation dated 11/14/89 is amended to read as follows: Wood, metal, or carbon stiffeners may be added to wood body runners (as in E.1.e. for plate runners) as long as the minimum wood body meets the imensions in E.2.a. and the stiffener is outside the wood body. No wood, metal or carbon stiffener may come between the insert plate and the slot in the wood body. No metal or carbon stiffening is allowed inside the main wood body. 12/01/2012 It is allowed to apply a coating to cover the surface of the steel plate, angle, or T used in a runner. The steel, without the coating,shall comply with the dimensions specified in E.1.a.,b.,c.; E.2.f. and E.2.h.

01/15/2013: In runner specifications and interpretations runner stiffening elements, i.e. “stiffeners”, and runner reinforcement have differing allowed uses, allowed materials, and dimensions.

On plate style runners, stiffening elements are controlled by specifications E.1.; E.1.d., e.,f.; E.4; E.6. and interpretations E. Runners dated 11/14/89, 7/1/92; four interpretations dated 1/15/2010; and I. Fittings dated 1/15/2010

Stiffening elements and reinforcement of the body of wood body runners are controlled by specifications E.2.a., d., e.; E. 4.; E. 6. and interpretations E. Runners dated 10/17/83; 11/23/87; 7/1/92; 11/30/98; four interpretations dated 1/15/2010; 12/01/2012; and I. Fittings dated 1/15/2010

On wood body runners, allowed material added to the body which is outside the allowed maximum body thickness of 1 1/32 inch (26.1 mm) is considered a runner stiffener or stiffening element. Allowed material added to the outside of the wood body, or in the slot of insert style runners, that does not exceed the allowed maximum body thickness of1 1/32 inch (26.1 mm) is considered external reinforcement.

05/23/2013: It is not permitted to reduce the thickness of the runner steel below the allowed minimum by rounding, fairing or tapering except as specified for the leading edge in specifications E.9 and E.12. Refer to the interpretation E.Runners dated 10/01/2010 and the diagram “19mm dimension”. The 3/4″ (19mm) dimension does not establish a line extending along the runner parallel to the sharpened ice contact edge below which the thickness of the runner steel is allowed to be less than the specified minimum.

F. Runner Base and Cut(Track)
3/12/07: Measuring F.2 In order to make repeatable measurements of runner cut as intended by this Specification the following methods should be used: Rigging should not be tight during measurement. The skipper must be allowed to loosen the rigging as required to relieve static tension. Sailor should be wearing normal racing attire, including helmet, goggles. etc. Mainsheet must be loose. The runners must be allowed to move. If on the ice, the boat may be pushed to allow the runners to seek a neutral position. If using a measurement fixture, the device must allow free sideways movement of the runners. The skipper should be in the cockpit in normal sailing position (lying in the cockpit with his shoulders against the seatback).

G. Sail
1977: It is not legal to use two ply Dacron 6.5 oz cloth for the top panel and bottom panels for reinforcement.

3/18/89: In Specification G.17, the location of the forward upper corner of the headboard is determined by projecting a straight line parallel to the luff (excluding the bolt rope) to the point where it intersects with a line projected from the uppermost point of the headboard and perpendicular to the luff.

11/20/2011 – Amend 3/18/89 to read as follows: In Specifications G.8. G.17 and G.24 the location of the forward upper corner of the headboard is determined by projecting a straight line parallel to the luff (excluding the bolt rope) to the point where it intersects with a line projected from the uppermost point of the headboard and perpendicular to the luff.

11/20/2011: In Specification G.8. the leech is a straight line from the head to the clew. Reference Specification G.17 and Interpretations G. Sail.

11/20/2011: In Specification G.17 the spelling of the word “leach” is corrected to “leech”.

11/20/2011: The batten pockets in all sails made prior to 1/1/2012 shall lie at 90 degrees plus or minus 8 degrees to the leech. These sails may be used in all DN races, including all championships. All other sails must comply with Specification G.8.

12/01/2012: Procedure for measuring a DN Sail
A. 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 and G.24.
  5. 5. Use the following points of measurement when measuring location of battens and batten pockets and pocket angles.
    a. 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.17 and interpretation G. Sail dated 11/20/2011)
    b. The top edge of a batten pocket is located along the top of the inside width of the pocket.
    c. 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. interpretation dated 11/20/2011) as the location of the hole in the head of the sail when folding to measure the girth. (ref. G.18)

B. 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. interpretation G. Sail 11/20/2011). All points along the top edge of the pocket must comply the 27″ (686 mm) minimum dimension from the head. (ref. 5 b. above)
  2. The spacing between the battens is measured between the centerline of the batten pockets where the centerline intersects the straight line leech. (ref. 5.c. above)

C. To determine the angle of the batten pockets. (ref. G.8)

  1. Measure the angle between the straight line leech (ref. 5.a. above) and the top edge of the batten pocket.(ref. 5.b. above)
  2. Measure one-pocket-at-a-time.
  3. Place the base of a protractor along the straight line leech, centered at the top edge of the batten pocket (ref. 5.b. above) , and facing the luff.
  4. Read the angle at the top edge of the pocket. (ref. 5.b. above)

H. Rigging
01/01/78: Boom pulleys may not be attached inside the boom by slotting the bottom of a boom and inserting the pulley into the slot and then picking up the sheave with a bolt or rod.

01/01/82: A track may be mounted on the boom for sliders to which the pulleys may be attached.

09/23/82: Mounting Pulleys on deck or boom by any means is acceptable as long as the rope and sheave are outside the boom or deck. No recessed block will be allowed in which part of the sheave or rope is below the back deck. (see also 11/1/84 interpretation)

10/17/83: It is not allowed to use a shock absorber (spring) between side stay and the fitting on the end of the runner plank.

11/1/84: It is not permissible for any part of the sheet block, or any hardware integral with the mounting of the sheet block, to be below the projected top surface of the deck, with the exception of the screws or bolts used to fasten the hardware to the deck.

11/10/73 & 11/14/88: Cable may not be used in place of mast hound. Hound may be made from strap or plate material. No leaders or bridles allowed.

I. Fittings
9/23/57: An adjustable footrest may be used.

9/23/57: Shock-absorbing steering chock – steering chock must be according to plan, but springs or rubber grommet may be added as shock absorber.

11/10/73 & 11/14/88: There is no limit to the number of holes in the tack fitting. Tack pin location may not be changed during a regatta.

11/10/73: It is not allowed to have two holes in the chock.

11/10/73: The number of straps on the mast hound is optional.

11/23/87: It is not allowed to use a long fitting to connect the mast hound with the head stay so that the position of the mast hound can be moved (within the allowed dimensions) with out having to make a new stay.

4/15/90: The degree to which the side runner pivots vertically in the chock may be restricted only by way of the friction on the sides of the chock which is controlled only by the tightening of the pivot bolt. Any other device to restrict the vertical movement of the runner is not allowed.

11/15/03: It is allowed to use a fixture providing additional height to mount the rear sheet blocks to the deck. The fixture must be mounted on the surface of the deck and may not be integral with the deck structure. This fixture must provide a fixed position for the block attachment (the blocks may not be moved while underway).”

12/01/2012: It is allowed for there to be more than one position for the mast hound or an adjustable fitting with multiple positions, providing the location of the lower mast hound bolt (pivot bolt) is within the range specified in H.13. The position may not be adjusted while the yacht is underway.

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