When the wind is on the bow, although the effective wind is greater than 10 knots, its forward driving component is so reduced that the boat's speed will be much less than 4 knots.
Xa umoya ungaphambili, nangona umoya onguwo umkhulu kunesantya esibekiweyo esingu -10 ilungu layo eliqhubela phambili kuthiwe ukuba isantya siza kuba ngaphantsi kwesantya esibekiweyo esingu-4.