Use of pre-preg carbon Only the highest grade pre-preg tows of T700 or TZ carbon fibre are used to give sailors the best stiffnessto- weight spar. This, in combination with our filament winding process, enables the highest fibre-to-resin content pre-preg to be used. The aerospace grade pre-preg has a UV stabiliser in the resin system to give the spars a guaranteed long life, even in the sunniest of climates. More fibres and less resin, mean lighter, stiffer masts.