Hi Fred

I can only refer to the carbon-beams I made for my ventilo.
They have a wall thickness of 3.5mm and a diameter of 120mm by a lenght of 3m. there are no dolphin-strikers as the diameter is quite big and the beams are very stiff.

the beams are reinforced at the place where it connects to the hulls and screws. they are made of unidirectional carbon fabric (400g/qm 12K HSC Carbon UD-Gelege 500mm width) from SP-Systems and has crosswoven carbon layer on top only for the optic.

The orginal Ventilo-Beams are also made of carbon, but are shorter (2.5m) and have a wall thickness of 2.9mm by the same diameter.

Good luck with your Project!
Andi