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A: 11' 0"

Maximum overall boat length 11' O" as illustrated, not to include rudder, gudgeons, head stay fittings, nor the flange of deck over hang as in molded Fiberglas boats.

Hull construction to be of any material with a minimum weight of 75 pounds. In no case will a structural part of the boat be unreasonably increased in any given area with the sole intent of merely improving the weight distribution in the hull.

The maximum beam permitted will be sixty (60") inches. No hollows or concavities greater than one (1") inch will be permitted anywhere on the sides or bottom of the hull aft of the front of the center board trunk.

All hulls must be monohull; tunnels, outriggers, wings, hiking boards and trapeze will not be permitted.

D: 15' 0"

No tolerance permitted in the placing of sail limitation marks on mast - 15' 0" from top of lower to bottom of upper mark - the sail is to be set between top and bottom marks.

E: 3 1/2"

Mast diameter not to exceed 3 1/2" including sail track

F: 9' 6"

Boom - 9 ' 6" maximum overall length of boom.

G: 9' 0"

Sail limitation mark 9' 0" from after edge of mast, no tolerance permitted.

H: 3"

Boom diameter not to exceed 3"

J: 5' 6"

Must not exceed 66" including bolt rope after determining midpoint.

17' 5 29/32"

This sail dimension should be checked, placing sail on floor and applying sufficient pull to unwrinkle sail. Check leech roach at this time for true round, including transition to head board if used.

N: 92"

Battens - Not more than Four (4) - Total length not to exceed 92" check sail batten pockets to see that battens submitted match batten pocket sizes.

O: 6"

Check sail to see that no batten is placed within 6" of spars.

P: 3/4"

Sail limitation marks shall be painted red or black on spars. Plastic tape will not be accepted.

S: 1 5/8" maximum

This dimension is measured from the extension of the leach true round if the junction of the leach and head is radiused. The angle of arrival of the leach may vary. A headboard may be used, but shall not be constructed so that the sail will not fit within the outline shown. A variation might be approved should the boat rope size and sail track clearance of a particular boat's spars absolutely require.

T: 12"

Moth emblem 12" outside diameter BLUE circle, Red M, recommended 18" below head of sail

U: 1 1/2"

Width of Moth emblem circle and stroke of letter M inside circle.


Sail material will consist of dacron or cotton. Windows allowed, maximum 400 square inches .


Sail shall be fastened to the boom so that no part of the foot of the sail will be more than three inches from the boom at any time during racing. No loose footed sails.


All sails measured must have current " approval stamp" for the year before any boat can compete in a sanctioned event.


All sails will display numbers. New numbers will be assigned to new boats and old ones without numbers will also receive numbers. Old boats can retain their original number.


All measurements and weights under this certificate will be maintained by the boat owner and can be measured anytime a question arises.

Rules Diagram