The J Class

Featured in Model Yachting #127

Robert Eger's J-Boat "Shamrock V"
by Linda Dennis, San Diego, CA.

Class Secretary

John Hanks, III
1849 Rainbow Ave. So.
Lake Havasu City, AZ 86402
928-680-7331

Description

The J Class models are 1/16th scale hulls of the J class yachts that raced for the America’s Cup from 1930 through 1937. The models are the largest recognized class in the AMYA with the hull lengths ranging from about 7 feet to 8 ½ feet and weighing between 65 and 90 pounds. The models carry from about 3000 to 4000 square inches of sail on masts that are 8 to 91/2 feet above the deck. The difference in sizes of the models is driven by the different sizes of the full size yachts. The Js were designed to a rule with a specific formula that allowed the designers to change dimensions of the hulls and sail area to arrive at the same answer. The full size yachts varied in size from about 120 to 135 feet in length and had waterline lengths from about 76 to 87 feet and they carried a crew of about 35.

There were ten boats built to the J Class specifications between 1930 and 1937, six in America and four in Britain. In addition six other large yachts sailing at the time were converted to the J rule. Drawings are available for all of the J yachts from several museums such as the Mystic Seaport Museum and the Smithsonian Museum. There are also several companies producing fiberglass hulls for some of the yachts. The hulls that are currently available in fiberglass are Ranger, Endeavour, Shamrock V and Whirlwind. Masts and spars are also available in extruded aluminum. In addition there are some skippers who prefer to build plank on frame hulls from plans. Keep in mind that there will be some scratch building required when you built your J model regardless of whether you start with a fiberglass hull or want to build a plank on frame model.

The J class is truly one of the most beautiful class of models in AMYA.

Visit the J Class Site for more detailed history and current state of the fleet!

 

Official AMYA Class Rules

J Class Rules (Effective 1 -1-2002)

1.0 HULL

1.1 Must be a scale model of one of the original "J" boats. 

1.2 Scale must be ¾ inch equals one foot. 

1.3 Exception: The keel draft can be two inches deeper than scale to help the stiffness of the model.

2.0 MAST

2.1 Height: Mast height may be to scale of the yachts original sail plan. Not to exceed 10 feet. (1988) 

2.2 Material: The mast is to be constructed of Wood or Aluminum.

3.0 SAILS

3.1 No restriction on sail area other than sail area may not exceed the scale sail plan area. 

3.2 Any sail plan that was used by the original boat from which the model was scaled, i.e. double head sails, Genoa, Spinnakers, etc. 

3.3 Maximum sail area for each model is as follows; 
Whirlwind - Whirlwind and Vanguard hull - 2478 square inches 
Whirlwind 1/16 scale - 4128 square inches 
Weetamoe - 4247 square inches 
Yankee - 4100 square inches 
Enterprise - 4265 square inches 
Shamrock V - 4241 square inches 
Rainbow - 4238 square inches 
Endeavour - 4253 square inches 
Ranger - 4245 square inches 
Endeavour II - 4243 square inches

4.0 RUDDER

4.1 Must conform to the original boat from which it was scaled. 

4.2 Exception: The rudder may be two inches deeper to follow the extended keel and two inches wider to provide extra maneuvering control.

5.0 DECK

5.1 The deck shall be made from a hard material such as wood, fiberglass, Formica or some similar material. Fabric and film decks are not allowed.

6.0 Displacement 

6.1 Each model yacht shall have a minimum ready to sail weight, that is the weight of the model when it is ready to race. 

6.2 The weight of the model shall not be changed once a regatta has begun. A regatta is defined as a race or series of races that constitute an event regardless of the number of days the event covers.

6.3 The minimum displacement for each model is as follows; 
Whirlwind - Whirlwind and Vanguard hulls - 63 pounds 
Whirlwind 1/16 scale - 77 pounds 
Weetamoe - 69 pounds 
Yankee - 72 pounds 
Enterprise - 62 pounds 
Shamrock V - 65 pounds 
Rainbow - 68 pounds 
Endeavour - 69 pounds 
Ranger - 81 pounds 
Endeavour II - 79 pounds

Effective January 2002