Recent Applications of Hydrofoil-Supported- Catamarans - Boat ...

10Figure 5: The E-Cat with foils at 42 knotsFigure 6. shows the E-Cat mainfoil at a speed of 44 knots during the trial runs. Asomewhat new flow phenomenon was observed which can not be classified as cavitationbut rather as low pressure ventilation, see the “white water flow” over the foil whichmoved forward with increasing speeds. At lighter loads the E-Cat achieved up to 46knots and the ventilation effect appeared even stronger, however, no cavitation erosionor performance reduction were observed even through the speed was far above thedesign speed of 40knots and the foil-tip profile thickness – chord – ratio too high forcavitation free operation.It is believed that the foil in close surface effect mode is not prone to cavitation asexpected. This means that much higher speeds will be possible when operating the foilsin close surface effect mode. Further research is necessary to clarify this newphenomenon.