The unique hull shapes of modern high speed vessels with their shallow transoms, fine angle of entry and shallow draft render them particularly susceptible to directional instability. A solution to this is to fit a Ship Dynamics High Auxiliary Steering System as part of an integrated steering system.
A high response rate interceptor or cantilevered foil is coupled to the main ship steering system. At low speed the fin is centered during normal maneuvering. At speed the Ship Dynamics High Auxiliary Steering System can be selected; just as an autopilot is and the primary steering locked in the ahead condition. The response rate and force of the high speed fin is typically a multiple of that of the primary steering system meaning that deviations in vessel track are arrested well before the vessel heading responds. Throttle back and the system seamlessly returns control to the primary steering system.
In the case of water jet driven vessels where there is typically no rudder, the presence of an appendage may be initially perceived as additional speed robbing drag. However when the drag of the rudder is considered in the context of the overall resistance of the snaking vessel and the lost thrust of an oscillating water jet, the rudder drag impact is insignificant. In commercial applications on large high speed vessels the speed gains of adding High speed auxiliary steering can be typically measured in knots. This directly translates to an operational fuel and cost saving.