AMYA Star 45 Class Rules, 2006, KEELS AND BALLAST BULBS
7.1 Keel will be of the style known as drop, and will be of the FIN and BULB type.
7.2 Keel fins may be solid or hollow and constructed of reinforced plastic, plastic laminates, fiberglass, wood or metal. (Note: Strength and integrity of the keel fins must be maintained whether built solid or hollow.) Keel fin shape is not specified but must follow the general shapes outlined on the reference drawing. However, keels will not be less than 6 inches nor more than 8 inches long (Fore and Aft) at the keel/hull junction, nor less than 4 inches nor more than 6 inches long (Fore and Aft) at the keel/ballast bulb junction.
7.3 Keels, keel fins and ballast bulbs may be removable, however, they may not be changed, interchanged, substituted or otherwise manipulated once any heat or series of heats in which scores will be compiled, has started. Mechanically movable keels or ballast bulbs are specifically prohibited from use in Star 45 Class Yachts.
7.4 Ballast bulbs may be constructed of any material not prohibited by the AMYA. The actual shape is left to the builders discretion, but will not exceed 9.75 (9 3/4) inches from the front of the keel bulb to the rearmost point of the keel or bulb.
7.5 Total drop (length) of the keel fin/ballast bulb combination will not exceed 11.5 (11 1/2) inches when measured from the keel/hull junction, before any fillers or streamlining is added.
7.6 Ballast may be made from any readily available material, such as poured lead, lead shot, etc. (Note: When using material such as lead shot, the mass must be solidified through the use of a bonding agent such as fiberglass or epoxy resin, plaster of paris, poured over and through in order to create a solid mass.)
7.7 Race directors may elect to use a template based on the construction plans to determine the keel length (depth).
7.8 Keel depth shall be measured from the center of the keel fin at the hull to the bottom of the ballast bulb. This measurement is from the edge of the bottom of the hull as it meets the side of the keel and should be determined during construction and before any fillet or fairing is added.
7.9 The Star 45 Class specifically excludes radio equipment, sail controls and batteries (power cells) from being considered ballast. This specification defines ballast as anything carried aboard the model for the main purpose of changing the weight distribution of the model and/or weight of the model. Ballast shall be fixed in place by gluing, fiberglassing, or bolting (bolts and screws).
7.9.1 Ballast may not be removed or relocated during any one regatta. The use of Velcro or similar quick release fasteners is prohibited as methods of mounting ballast.
Lester Gilbert on understanding of sail making for model sail boats
Lester Gilbert wrote:
For anyone interested in sailmaking, Ive just finished editing Larry Robinsons "Making Model Yacht Sails" (part 1 only) booklet and have published it as an "international" edition. Ive done this, not to get rich (cos this isnt going to happen to either me or Larry or anyone else connected with this enterprise!), but because Ive spoken to a lot of sailors who want to make sails but dont know the "right" techniques, and who are being misled by incorrect accounts of how this might be done.
A sail block
(Illustration from Larry Robinsons "Making Model Yacht Sails")
From my understanding of sail making, there are two ideas I want to contradict.
The first idea is that you can make sails by accurately cutting a curve on a panel, and then attaching it (stitching, gluing) to another panel. Well, while you might be able to cut a good curve some of the time, your fingers just dont have laser accuracy in them to stick A to B and youll hardly ever obtain reproducible or reliable results. (It might be possible to butt-join the curved edge to another curved edge with a little more reliability, but this doesnt yield what the Equipment Rules of Sailing define to be a seam. Such a sail couldnt be used in sanctioned IOM competition, though it would be OK in a development class.)
The second idea is that you can drape your panels over a "camber board" and get a nice shape that way. Well, let me be clear about what Im knocking here. I take a "camber board" to be a length of curved surface, where the curve is like the surface of a cylinder. In this case, your panelled sail will have exactly the same shape as a single un-panelled sail and, if you wanted a three-dimensional shape, youve wasted your time (though the result certainly looks the part).
Larrys booklet is the only source I know which carefully explains the use and construction of a sail block. I am sure that this is really the only way (in your garage, please, not in some specialist workshop!) to make professional sails, to obtain reliable and reproducible three-dimensional shaping, and to be able to tweak and change your shaping as you learn about the whole business.
(Warning: Yall should know I have ten thumbs and have never made a sail yet. What I have done carefully is to watch and talk to those who do, both professionally and as home builders, and measure the results. Making Larrys booklet available internationally is my way of telling you what Ive learned.)
Bob Wells will be able to ship this within the USA, and I expect that it will also be available from Don Ginthner at GBMY. For worldwide sales, contact SAILSetc. Bob Wells e-mail is "bob" at "islandinet.com", GBMY is "rcsailing" at "gbmy.com", and SAILSetc can be contacted through "sales" at "sailsetc.com".
Ive attempted an analysis of how blocks work on a new page, Sail blocks analysis, and have a new spreadsheet there to help.
