Forces on sails (3 m) = 5-m/s (≈10-knot) wind at 3 m above the water would be approximately "V" (15 m) = 6 m/s (≈12 knots) at 15 m above the water. In hurricane-force winds with "V" (3 m) = 40-m/s (≈78 knots) the speed at 15 m would be "V" (15 m) = 49 m/s (≈95 knots) with "p" = 0.128. This suggests that sails that reach higher above the surface can be subject to stronger wind forces that move the centre of effort ("CE" ) higher above the surface and increase the heeling moment. Additionally, apparent wind direction moves aft with
North Sails the 3DL line of upwind sails in 1992. In the 3DL manufacturing process, aramid or carbon fiber yarns and layers of polyester (PET) film are laid over a computer-controlled mold that is configured to assume the airfoil shape of the sail, and then thermo-formed to produce a laminated sail with the intended three-dimensional shape. North Sails manufactures 3DL sails in facilities in Minden, Nevada, and Sri Lanka. In 2009, North Sails began using pre-impregnated tapes of carbon and UHMPE fibers on its full-sized articulating molds. When thermomolded, the layers of reinforcing material consolidate to form a seamless composite sail membrane,