General
The measurement variations of the foils are quite small. Assuming you want to comply with the class rules, the first order of business is to get a copy of the official foil drawings from your association's secretary or chief measurer. Having your boat measured and certified adds to the value of your boat whether you race or not. Please bear in mind that not all class rules are about racing, actually there are quite a few rules that are about safety and for that reason as important to cruisers as to racers.
 
Once you have obtained a copy of the drawing, you will notice it is on non-stretch polyester "paper". So that you can use the drawings correctly, I should explain how a measurer uses the drawings. The major part of the foils has to stay within the drawing outline, allowances are +0 mm and -7 mm. A measurer will place a foil on the drawing and use a square angle to project the foil onto the drawing. You are allowed to shift and turn the foil into what you think is the best measurement position. This means that if your foil is 14 mm too small, you are allowed to shift it until you have 7mm on either side relative to the drawing. A measurer would pass your foil in that case, but not with 14 mm on one side. 
 
Next thing to do is read the class rules concerning foils. These rules give you the maximum chamfer, which is not much: 2 inches on a rudder blade, 2.5" on the board. This means you cannot make a true foil, for example a Nacra-shaped foil. The class rules can be viewed or downloaded from any of the Wayfarer association's websites.   
 
Materials 
Uncle Al already suggested mahogany, a very beautiful, easy to work but very expensive solution nowadays. A good alternative is Abachi but that may be too heavy (see class rules on maximum weight of board). I have a board that is made of Abachi and Cedar. Pine may be a little too soft in the long run (not sure). Cedar is light weight and has nice long grain. Abachi provides the stiffness and the cedar brings the weight down. In my CB finishing essay are some pictures that show where the Ibachi is (dark brown parts) and where the Cedar is (light colored wood). The stiff and strong Abachi goes mainly into the leading edge where most of the "work" is done. 
 
Alternatively, you can use plywood but only the very best marine quality available. I have seen CB's fail the first time out on the water, after a winter of hard work. The average building ply (waterproof or not) won't cut it. Think of it this way, you and your crew must be able to stand upright on the tip of the CB to right the boat after a capsize. And that is only a portion of the forces a CB has to cope with while sailing. Think of your boat as an aeroplane on its side. Like an aeroplane with only one wing can't fly, a sailboat can't sail without its foils. They are, so to say, your sails under water. A long story but I hope to make it clear that the forces on the foils are about equal to those on your sails. The foils counterbalance the forces on the sails less the crew weight. I am sure you already had the pleasure of discovering what wind can do in your sails. Similar forces act on your foils. This also explains why your foils are just as important as good sails, and I cannot understand the care and effort some sailors put in their sails while totally neglecting their foils.  But back to plywood now. Someone suggested to me once to use two half thickness plates of ply and glue them together in such a way that more of the wood grain goes in to the length of the board and less goes grain is in the width of the board. I have never tried this but it seems a good idea to strengthen a CB. 
 
Fabrication
As stated before, watch the tolerances carefully in everything you do. When using ply, it is a matter of copying the outline from the drawing to the wood and then using a jigsaw. You could use a needle in a cork to punch small holes through the drawing in to the wood. After that, it is just a matter of connecting the dots. Always leave some extra material. Only when the board is nearly finished, do you sand it to its final dimensions.
 
A laminated board is a bit more difficult. You need to glue together a number of strips to avoid warping. I would suggest you use quarter-cut planks and turn the grain of each plank 90º relative to its neighbor. Quarter-cut wood has less chance of warping or developing all kinds of unwanted strains in the wood. By turning the grains relative to one another, possible warp will be counteracted by the neighboring planks. 
 
Once the planks are glued together to a board a little larger than needed, it is time to call upon a friendly carpenter to have it machine planed to its required thickness. I would not try to do this myself. A machine does it in a few seconds. Because of this, you should use planks that are a good bit thicker than the board will need to be. As for glue, I would probably go for epoxy but there are quite a lot other good waterproof glues out there as well. 
 
Once you have your planks glued together and planed, it is time saw to shape just like plywood.    
     
Chamfer
The chamfer can be made by hand by drawing a number of helper lines on the wood. These lines are on both sides on the front and the rear. With patience and care you sand carefully to the first lines on the side and front (or rear) of the foil. Once you are happy with the chamfer all around the board you start to sand it to the second set of lines. This process continues until you reach the final line.
 
If I read back the above, I am reminded again why I choose to have a machine-milled board. You can buy ready made boards (ply or planked) from suppliers. Since they all use CNC milling, their main costs are in the finishing. Finishing is mostly labor and therefore expensive. If I look at the cost of the wood, and the time and trouble involved, I would, unless I had some left-over wood available in the shed, buy a ready-made, unfinished board and finish it myself. That is something that can easily be done by any Wayfarer sailor. 
 
Finishing
Once you get to the stage where you need to finish your foils, please have a look at my essay on that subject here:
 

• It should be obvious that foils that will be finished with glass fiber should be slightly smaller than those that will be epoxied only. Especially the trailing edges can be made much sharper when they are finished with glass and epoxy. For this you may want to make the foil up to 5 mm smaller.

• Note that you do not want the aft edge as sharp as a knife. Not only is this dangerous for the crew, but hydrodynamics tell us that there is less resistance (smoother flow) when there is a very small flat surface (1 mm) on the aft edge. 

• Most laminating epoxies do not have a UV filter. Check this on the package. If it does not, you should finish the epoxy with a varnish that does have an UV filter. On the other hand, how much sun reaches the surface of the centreboard? Perhaps some varnish on the rudder only?     

• Give your foils as much TLC as your sails. Take them out every winter let them dry thoroughly and give them a new coat of paint/varnish just before the sailing season starts again. Do not make the mistake of drying foils in the attic. Heat alone does not dry, you are looking for lots of fresh air. Put your foils somewhere protected from rain and sun but open to wind. 

 
I think that covers it, if not don't hesitate to ask.
 
Best wishes,
 
Ton Jaspers (W10445) 
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