Woven Roving and Knitted Fabric
Woven roving is a great option to use in boat building, especially when used with chopped strand mat. Woven roving is a heavy, coarse plain weave cloth. Bundles of roving are woven together loosely at 90 degrees. It comes in 18 and 24 oz weights. (We only sell the 24 oz woven roving by the yard).
Woven roving is used to quickly build up thickness. The continuous filaments add strength. A drawback is that with the woven bundles there is crimping. The crimp points can fracture.
Typically when using woven roving, it is alternately layered with chopped strand mat. The reason to use mat with roving is because of the knobbiness (bumpiness) of the roving. It is hard to adhere another layer of roving or cloth to it. There will be many voids left behind if done so. It will also be really heavy from the extra resin needed to fill in those voids.
Using woven roving is a great way to build up strength and thickness in a laminate. It can be heavy, though.
Knitted fabric is also a great option in boat building and in the composite industry. The most common knitted fabric is DBM 1708. The 1708 is a 17 ounce +/-45 bias fabric with a 3/4 ounce chopped strand mat stitched to it.
Knitted fabric is bundled and stitched together. It provides maximum directional strength and wets out fast. It saves time in multi-layer layups. There is no crimping since the fabric is stitched instead of woven.
Knitted fabric is compatible with polyester, vinyl ester and epoxy resin.