This calculatoris useful. The area of an 8x8 is about six square metres (since (8x12x25.4/1000)2= 5.945) which in a 20-knot (10.2m/s) wind will apply a force of 375N, equal to about 38 kilos or 83lb. 20 knots is not much of a breeze. Calculating the tension applied to a t...