Mission Statement for the US Marblehead class
to be sanctioned by the American Model Yachting Association.

       2.    Because of the 80 year history of the “M” class boats of pre-1970 designs will be governed by the old “Model Yacht Racing Association of America” rules. “M” boat designs of post-1970 origins will be governed by the early AMYA rules.

      3.                 Regattas and AMYA events are to be open to all “M” class model owners regardless of design era. In these events boats of different design eras will be scored and awards given separately.

      4.      The US “M” 50/800 class will have an elected class secretary.  Each boat in the class will be judged to fit into one of four design time frames

            1- Designs 1931 to 1945

            2- Designs 1945 to 1970

            3- Designs 1970 to 1985

            4- Designs 1985 to present

Each design era group may choose to have a fleet captain to act as an advisory committee to assist the class secretary with issues that are bound to arise.

    5.        Boats eligible for membership in the US “M” class will be governed by the AMYA bylaws 9.2.1, but will abide by the weight and keel length restrictions.

   6.         Fleet Captains may promote separate events for their group, but AMYA events will be inclusive; every design era will be welcome.

   6.         The web page of MMYUC has complete rules for A.M.

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US “M” Class Rating Rules

Marblehead class 50/800 models of pre-1970 design will adhere to the following measurement rules:

The Rules of Pre-1970 Boats

1. Hull measurement

Length of hull will be 50 inches plus or minus ¼ of an inch.

2. Sail Area

Sail area not to exceed 800 square inches, triangular measurement. The roaches of the sails and foot round are not to be counted in the sail measurement.

3. Prohibited

• Sliding or adjustable keels.
• Centerboards; but not to prohibit removable keels.
• Leeboards.
• Bilge boards.
• Bowsprits.
• Overhanging rudders.
• Movable ballast except for removable keels.
• Prognathous keels (No portion of the keel can project forward of any part of the leading edge the keel.)
• Metal fin keels.
• Ballast material of greater density than lead.
• Multi hulls.

4. Garboards

Hallow of the garboards to be not less than 1 inch radius. (May be checked with a washer of 2 inches in diameter.)

5. Ballast

Ballast not to be changed or moved during a race event.

6. Draft

To be determined by the deepest draft of a known period boat.

7. Hull weight

A. Minimum hull weight to be 2.5 pounds. (Without rig, ballast or fin.) Winch and servos deck and batteries are to be in place.

B. Hull shape: No restrictions on L.W.L., beam, freeboard or tumblehome.

C. Models may carry a bow bumper of a resilient material restricted to ½ inch thickness.

8. Rig

A. Rig not restricted.

B. Height of jib stay attachment to the mast not to be higher than 80 percent of the measurement on the mast from the deck to the bottom of the headboard.

9. Mast and Spars

A. Height of the mast not limited.

B. Mast and booms will be no greater than ¾ of an inch in diameter or if flat-sided no greater than ¾ of an inch on a side.

C. Area of the mast or booms not counted in the sail area.

10. Sails

A. Sails may be single or multi-panel.

B. Roach of the mainsail not to exceed 2 inches, roach of jib not to exceed one inch.

C. Foot round of the main or jib not to exceed 1 inch.

D. Mainsail battens not to exceed 4 in number nor be longer than 4 inches.

E. Jib battens not to exceed 3 in number nor be longer than 2 inches.

F. Headboards not to exceed ¾ of an inch measure to the bottom.

G. Spinnakers are permitted but are not to be flown from higher than the jib stay at 80 percent measurement.

H. Spinnaker poles no longer than 15 inches.

Post-1970 “M” 50/800 models will follow early AMYA class rating rules with two stipulations not found in the early rules. Intent of these rules is to facilitate the consistency of the R/C sailboat models of similar size.

The rules of the post-1970 boats

1. Hull

A. Hull length to be 50 inches, plus or minus ¼ of an inch.

B. 1/2 inch resilient material bow bumper attached to the bow of model above the waterline.

C. Minimum weight of the hull shall be 2.5 pounds with the winch, servos, batteries and rudder installed. The rig, keel fin and ballast are not included in this weight.

D. Maximum depth of the keel from the bottom of the hull to the bottom of the ballast shall be 20.0 inches.

2. Prohibited

• Moveable keels except removable keels.
• Centerboards.
• Leeboards.
• Bilge boards.
• Bowsprits.
• Overhanging rudders.
• Outriggers.
• Multi-hulls.
• Moveable ballast.

3. No limits on L.W.L, beam, freeboard or tumblehome.

4. Spars

The minimum dimension of spars if round, is to be ¾ of an inch in diameter. If spars are to be straight-sided, ¾ of an inch on a side.

5. Sails

A. Maximum sail area is to be 800 square inches.

B. Measurement of the mainsail is to be to the AMYA formula measured from the tack to the bottom of the headboard.

C. The jib is the same as the main except measured to the eye instead of the head of the sail when a headboard is not used.

D. The base of the headboards is not to exceed ¾ of an inch.

E. The roach of the sails

Main not to exceed 2 inches and may have 4 battens 4 inches long.

Jib roach not to exceed 1 inch and may have 3 batten 2 inches long.

F. Maximum height of the main sail is 85 inches from the deck to the bottom of the headboard or to the eye of the halyard if no headboard is used.

G. Height of the jib stay attachment to the mast shall not be higher than 80 percent of the height measurement from the deck to the bottom of the headboard.

I. Spinnakers are allowed

Spinnakers are not to be attached higher than jib stay 80 percent mark.