For dredging a tunnel right under a vessel from one side to the other a powerful craft could not work effectively in a depth more than 6 ft greater than her normal draught.
Ekugutyuleni itonela ngaphantsi kanye kwenqanawa ukusuka kwelinye icala ukuya kwelinye, inqwelo yokuhamba enamandla ayinakusebenza ngempumelelo kubunzulu obungaphezu kwesithandathu seenyawo esingaphezu kobungakanani bokutshona kwenqanawa emanzi okuqhelekileyo.