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
Forces on sails total aerodynamic force (F) on sails, which is a function of apparent wind velocity (V) and varies with point of sail. The forward driving force (F) component contributes to boat velocity (V), which is, itself, a determinant of apparent wind velocity. Absent lateral reactive forces to F from a keel (in water), a skate runner (on ice) or a wheel (on land), a craft would only be able to move downwind and the sail would not be able to develop lift. At a stable angle of heel (for a sailboat) and a steady speed, aerodynamic and hydrodynamic forces are in