Best practices for carbon layup of a dagger-board

Here's my dilemma. I'm building new curved dagger boards for my A-Cat.
They are 15 cm X130 cm with a 190 cm radius. I have molds that I have used before
(both boards failed on the same day (high winds + heavy skipper ...)
so I am increasing the amount of uni fibers.

The question is should I do the layup in one shot (bag and vacuum) or just do 3 layers(plys) at a time and bag it in 3 or 4 stages?

Any thoughts?

Thanks Les

 

1 shot. All the resin is the same batch, same mechanical properties, no secondary bonding issues etc...

Check the design, Uni fibres, reinforced with 30% cloth weight in +-45deg fibres interleved in the UNI. You also need 90deg fibres aswell - at the end of the board and where the board exits the case, in other words, anywhere its pressed against the case under load.

I would also use a higher density core where the board is pressed against the case, and perhaps check the load along the rest of the board to make sure your core has enough shear strength in general. A higher density foam of maybe 130kg/m3 might be required, and perhaps 200kg/m3 where its pressed against the case - just as an example.

 

Thanks for the input, Les

 

Can anyone give any tips on the best way to join the two halves of a centerboard. It seems like it would be best to wrap the seem in glass or carbon. (What ever the material of choice is) but the. You lose the nice molded shapes that you created the mold for.

I'm just thinking of making a copy of my moth foil so I have a back up. I've done plenty of repair work but never made a complete part from a two Piece mold and am just looking for a few finishing tips.

Thanks

 

Drew, on the boards I've made lately I use a solid carbon spar. So i run a bead (or three) of west 610 to join the leading edge, then use the same at the spar joint and trailing edge.
I've used this process on the afore mentioned boards when I turned them into "L" foils
http://1.bp.blogspot.com/-UNMNYjU3cMc/Utn3_4ij96I/AAAAAAAABZM/-AsEJGCmdAI/s1600/DSCF2935.JPG


Les

 

Boards and keels I've worked on commercially have usually had a rebate down the leading edge and bottom so the db tape does not ruin the shape.
The internal and trailing edge are epoxy glued.