I built a set of rudders and daggers for a viva 27. The rudders were 1 3/4 in thick, by I think 38 long and were very heavy solid mahogany. I used the originals as cores planed them down about 3/8 3/16 from each side and then cut off the leading and trailing edge leaving a top w/ a tapered stringer. I then glued on 1 lb styren foam. A few templates and and using my old surfboard shaping skills. 1 layer of of uni-knitted "rutan" glass "highly recommened" about 2/3 lenth and then 1 layer of 4oz glass. a little micro light. the new rudders were approx 48 in long an extra 8 in. with the last 12 in or so just, an egg shell. skin. new rudders were about 1/3 the wieght. With an much improved foil. I used a naca 12 foil. If I did it again I use the resource "here" to get a better foil. As for daggers, I used www.flyingfoam.com had Bob cut the cores with a cnc machine. again glassed w/ approx 10 layers of the Rutan uni-knitted glass. 1 layer of 4 oz glass. a little micro light. new boards were great I got close to a naca 12 foil but was restricted by the slot. new daggers were 8 ft 4 in long. and wieghed about 30 lbs each about 50 lbs lighter than the originals. In my opinion, the wieght savings vs strenth vs cost I would look at the new cloths being developed by the airplane composite company's. The foils I built were with in 10-15% of the wieght of a full carbon foil. But approx 1/3 the price. These are my opinons based upon 20+ years "part time" of fiberglass and water craft production and airplane restoration. PM if you want or need an opinion. Question has anybody out there built a set of aluminum boards I'm considering it for my new project "C-class" if so I would like to see how they were built.