DN Specifications

I. Fittings

  1. DN Class Information
  2.  » 
  3. DN Ice Yacht Specifications
  4.  » DN Fittings Specifications


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

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
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  
  Min Max Min Max
a. Width 3-3/4 95.3
b. Horizontal distance from the pivot axis of the steering runner to the aftermost end of the bow tang: 8 203.2
c. 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, including Mounting Hardware English   Metric  
  Min Max Min Max
a. Height (from bottom of skin of fuselage): —  3 76.2
b. Length:     6 152.4
c. Width:   4 —  101.6


17. Mast Step Mounting Hardware English   Metric  
  Min Max Min Max
a. Length:    9 228.6 
b. Width:   76.2



Effective May 31, 2020

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, 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.

1/15/2010: 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.

9/20/2013: The bow tang, reference specification I.14 must be mounted at the forward most (bow) end of the fuselage and all parts of the tang, with the exception of the fastenings attaching it to the fuselage, must be outside the fuselage.