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Revision effective March 23, 2003


The purpose of these rules is to maintain the integrity and uniformity of the one design Manta Winjammer and Twinjammer yachts and racing fleets. Each owner is responsible for keeping his or hers yachts within these specifications.


A yacht shall participate in a race in an event only by fair sailing, superior speed and skill, and except in team races by individual effort. However, a yacht may be disqualified under this rule only in the case of a clear-cut violation of the above principals and only when no other rule applies.


Tech inspections will be avoided whenever possible, it is expected that everyone will abide by the Fair Sailing Rule. Tech inspections of a yacht will only occur, at the request of an owner of his or her own yacht, or at the request of a minimum three other participating in a race or series of races.


1. Yachts shall be a Manta Winjammer or Twinjammer manufactured by Manta Products Inc

2. Sails and Battens shall be supplied by Manta Products directly or through a Manta Dealer. Sail repairs may be done by anyone. Factory supplied sails may not be modified for the purpose of improving the sailing characteristics. Battens must be used as supplied by the factory and their shape may not be changed.

3. Wheels to be supplied by Manta Products Inc, directly or through a Manta Dealer.

4. Wheel Bearing to be supplied by Manta Products Inc. or equivalent.

5. Tires to be supplied by Manta Products Inc or equivalent size as follows: 5.30-4.50x6, 15-6.00x6, 4.10-3.50x6, or 13-5.00x6. Rear tire maximum height is 15 inches.

6. All other mechanical replacement parts to be supplied by Manta Products Inc, directly or through a Manta Dealer.


A. Replace the topmast plastic with a rounded piece, no higher than inch (1”) to allow the mast to slide into the sail pocket with greater ease.
B. Rear axle may be reinforced with available material, provided the reinforcement is made internally only within the factory axle tubing between the axle spindle inserts. Recommended: Douglas Fir wooden dowel with a slip fit.

C. Rear axle spindles may be replaced with longer bolts. Wheels are not to exceed 86.25” in width for the Twinjammer and 64” width for the Winjammer.

D. Steering “T” may be moved fore or aft to suit pilots’ height, either by the addition of a longer the rod supplied by Manta Products Inc directly or through a Manta Dealer, or by cutting down the existing stock tie rod.

E. Steering “t” post may be reinforced from the top of the post to mid frame rail with a steel or aluminum piece of material 16”-18”x1-1/2” If the threads are worn in the steering tie rod, a clevis pin (with appropriate pin or locking ring) or a 3/16” bolt (grade 5 or better) with bolt hole center no less than ½” from end of tube may be added to retain the tie rod to the pivot.

F. One 3” hexaracket block may be attached to the mast between the boom fork and the base of the mast. Twinjammer stock (4) 1-1/2” blocks max., all mounting locations may be upgraded to (4) 2-1/4"”Harken #001 or #002 or equivalent. Winjammer stock (3) 1-1/2"”blocks maybe upgraded to (3) 2-1/4” Harken #001 or #002 or equivalent.

G. Seat and seat tube padding may be added, but the seat position, size or angle shall not be altered in any way.

H. Trampoline and hammock seat to be supplied by Manta Products Inc directly or through a Manta Dealer. Trampoline may be reinforced or replaced by any material suitable for the purpose. The replacement material trampoline must be of the same or similar size as the original.

I. Mechanical batten adjusters are only allowed on the Twin. Mechanical adjusters may be purchased from anyone. A batten may be shortened to accommodate a particular mechanical adjuster. A hole may be drilled to accommodate a particular batten adjuster.

J. Internal wheel spacers between the wheel bearings supplied by Manta Products or Manta Dealer. Wheel washers may be coned to reduce friction.

K. Manufacturer assigned or US sail numbers at least 8” in height shall be displayed in a legible manner on both sides of the sail. (Staggered, Starboard side higher.)

L. Tell tails, wind vanes, direction indicators and speedometer allowed.

M. Strut preventer (not adjustable during a race) is permitted to help prevent sail damage.

N. The Twinjammer Mast Reinforce Retrofit is allowed to keep the mast mid-section from bending.

O. Yacht and sail graphics in the bottom panel only. Except for a sail makers standard slicker or insignia, advertising shall not be allowed.


1. The carrying of a co-pilot or ballast is optional. However, a co-pilot or ballast shall not be added, deleted or changed during a regatta.

2. All pilots shall wear a fastened stock seat belt, an approved safety Hard-Shell Helmet and eye protection at all times during racing.

3. When, during the course of a race, a yacht has come to a complete stop, a pilot may restart his yacht by using his/her foot to push three (3) times in succession. The yacht must then come to a complete stop before the pilot can push again.

4. All NALSA racing rules not in conflict with these rules apply


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