Here's the tunnel fin for the #Baron_surfboard taking shape.
Because this tunnel fin setup also has a planar fin in the form of a bulb tipped flex fin, it won't have to handle high angles of attack, so we are able to use a very thin fin for low drag, just as we did with the original D 11-9 prototype shown below:
http://www.youtube.com/watch?v=WQ6M9GY1XC0
The tunnel is only 6mm thick, and has a chord ratio of 6% which is very low.
Because the tunnel is so thin we are making it from 22 layers of thick brown paper and resin, it's the same paper which we use for drawing plans. Paper and resin is a sort of low tech carbon fibre laminate and is immensely strong.
The tunnel mould is a piece of plumbing pipe of 200mm diameter, we,e added some poster pint to tint the glue lines
