You are here

Interpretations of the Official Specifications

by the Technical Committee

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 theoutside 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.
12/10/2011
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 Section A. Fuselage, Section H. Rigging, and Section I. Fittings and the Interpretations in section General, section A. Fuselage, section H. Rigging, and Section I. Fittings.
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.
1/15/2010
When the use of the reinforcement bar or stiffening element that is associated with the “Kent” style chock does not comply with interpretations I. Fittings dated 1/15/2010, and E. Runners dated 1/15/2010, the bar will be considered part of the chock and must comply with the materials as specified in I. 13. and will be included as hardware in determining the overall length of the runner plank as specified in B.1.
11/30/98 amended 10/6/2011
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 n 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.   NOTE:This interpretation has been amended , reference interpretation 12/01/2012
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.
  1. 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").
  2. 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.
10/01/2010
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.
10/01/2010
Diagram 19 mm Dimension (attached to be published in Runner Tracks and in the yeabook). [img_assist|nid=133|title=|desc=|link=node|align=|width=640|height=376]
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.

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:

  1. Rigging should not be tight during measurement. The skipper must be allowed to loosen the rigging as required to relieve static tension.
  2. Sailor should be wearing normal racing attire, including helmet, goggles. etc.
  3. Mainsheet must be loose.
  4. 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.
  5. 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.
9/11/1999
It is legal to use Contender 6.5 oz. Polycote cloth in the construction of the sail.
5/6/2004
The specification of weight is a nominal cloth weight. This specification of 6.5 oz/sq.yd. refers to a “sail maker’s yard”, which is 36” X 28.5“. Sails built prior to July 1, 2003, which complied with the specifications at the time of manufacture will be allowed in all IDNIYRA regattas.
11/29/2010
In specification G.9. the batten width is measured at 90 degrees to the length. Batten thickness is the smallest of the three dimensions, i.e. length, width, thickness. There are no restrictions on batten thickness.
11/29/2010
Specification G.12. excludes batten adjustment from the factors that alter sail characteristics. Battens may be fitted only in the pockets allowed in G.7. and may protrude from the pocket at the leach end for the purpose of providing a means to secure the batten in the sail and adjusting the tension. There is no restriction on the tensioning of battens in the pockets and at any time battens may be interchanged in the allowed pockets.
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
3/18/1989 amended 11/20/2011
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.
12/01/2012

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 and G.24.
    5. Use the following points of measurement when measuring location of battens and batten pockets and pocket angles.
      1. 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)
      2. The top edge of a batten pocket is located along the top of the inside width of the pocket.
      3. 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)
  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. 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)
  3. 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 fittistyle="{list-style-type: upper-roman;}ng 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, with the exception of devices as allowed in Specification I.12.
11/12/03
It is allowed to use a fixture providing additional height to mount the rear sheet blocks to the deck. This 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).
12/12/07
“Kent” style chock - Either the inside or outside flange of the side chock may be reduced in size to allow clearance for runner stiffening elements. When viewed from the side, the profile of the chock must meet all dimensions specified.
01/15/2010
The reinforcement bar or stiffening element that is associated with the “Kent” style chock is allowed to be attached only to the runner and must meet all requirements of a runner stiffener. Reference Specifications E. 1.e; E. 1.f.; E. 4; and Interpretations E. Runners, 11/14/89; E. Runners 7/1/92; E. Runners 1/15/2010.
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.