For use in general sheathing work, more common with model makers. Twill weave has good drapability, it is also a very ‘soft’ cloth that will laminate into awkward shapes and tight corners.
To produce the diagonal rib one or more of the warp fibres weave under and over two, or indeed more of the weft fibers in a regular repeated manner, this in turn produces the distinctive diagonal rib.
Twill weave cloths have a front and back side, unlike the plain weave cloths. The front side has a slightly more pronounced weave and is more attractive, this face is used where the fabric is seen more of, ie clear coated surface or next to the Gelcoat if used for more cosmetic reasons.