Well I think there is. The nozzle is a foil section rapped around the prop. This will cause the water to begin to flow prior to meeting the prop. The higher velocity of the water will allow the sub to achieve that much more speed relative to the water meeting the prop before the noisy cavitation begins.
perhaps, but not all that much in noise reduction I shouldn't think. Although the bollard pull increase may well be useful at the lower speed towing what ever in currents found close in with shallow water.
Ah! Just thought. Cavitation will occur in shallow water at lower prop rpm than is deep water due to less water pressure in the shallows. This sub is designed to operate in the shallow and the Kort Nossle help keep it silent.
