A vessel with a hydrodynamic duct for flow management at the bow thereof, a duct which as a pair of lateral walls (2, 3) with a hydrofoil section on either side of the bow connected with a horizontally oriented or inclined wall portion (1) with a hydrofoil section, the duct being displaceable in the vertical direction between positions (a) and (b) and contributing in the reduction of wave making and frictional resistances through differentiation of the flow within from the flow outside the duct in cooperation with a bow which has longitudinally extending rectilinear or convex side walls (102, 103). The lateral walls (2, 3) have their trailing edge at a constant distance from the side walls (102, 103) of the bow, while they might for aesthetic reasons comprise movable hydrofoil section coverings (2′, 3′) or internal sheet laminates (20′, 30′) which protrude outwardly during navigation of the vessel and retract inwardly when the vessel is stationary in a port destination.