What I can tell you about the Carbon 50:50..

Marine grade alu' was impossible to find around here to suit the beam purpose. So a variety of tubes from 18mm - 80mm was constructed to suit a variety of jobs on the cat.

Then various combinations of composite were made across the range. This is 100% Carbon, 50:50 Carbon/Glass and 100% Glass.

The 50:50 was used on the rear as the pricing of such a unit is way below the 100% Carbon price. In this case I believe it was cheaper than the marine alu' equivalent which would have had to be imported.

So far its stood up to the task well and I've heard that Pro-Sail have now redone the layup schedule so that any new tubes produced will be about 4 times stiffer as well a mush improved hoop strength.

The tubes are built around a male mandrell with the pre-peg' being rolled on under pressure by a machine which looks like a huge cigarette roller then baked in an oven.

If you'd like samples or more info'. drop pro-sail an email. Hope that helps.

cheers