Lesson learnt - don't allow uni fibres to be kinked.

While under kite a few weekends ago, with my brother steering, me up front, we blew the port rudder box up. We didn't seem to be going that fast, maybe 15-18 knots and have done 19knots previously without the kite.

Upon inspection, the initial failure point seemed to be a "kink" in the bottom pintle carbon uni laminate. The fibres deviated about 3-4mm off a straight line over about 5-6mm, so the angle wasn't 90degrees. The laminate was about 3x20mm, which should be enough for the application under normal conditions.

Luckily I wanted to make some mods anyway, unfortunately this explosion has forced me to make the mods earlier.