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
Polytarp sails Polytarp sails Polytarp sails refer to sails constructed from rectangular polyethylene tarpaulins. Home boat builders often favor these synthetic "sheet" sails because the materials are inexpensive and easy to assemble into functional, durable sails. The usual construction method involves The sail can be strengthened by adding reinforcing material to the corners and stitching around the edges of the sail. Adding grommets to the corners and edges will allow the sail to be attached to the mast and spars. Because these grommets are placed through doubled material and behind the reinforcing line inside the sail edge, the resulting attachment points have