The Adaptive Steering and Stabilising Autopilot (ASSA) system is a control system which combines the control signals for course keeping and roll reduction. Thereby the rudder and the steering gear accomplish two functions: steering and roll stabilization.Roll stabilization is achieved as the rudder applies a torque against the roll motion, using the same principle as a conventional fin stabilizer.

As a system integrator for naval ships, RH Marine has provided state of the art Integrated Bridge Systems for numerous naval customers all over the world. The RH Marine ASSA design for Roll Rudder Stabilisation (RRS) operation is based on a system as delivered for the German Frigate F124 and the Netherlands Navy M-Frigate and Air Defence Command Frigates (LCF).

Advantages of the RRS system

The system is a cost effective, technologically advanced alternative for fin stabilisers. The ASSA has been designed to be flexible and open. 

  • Low life cycle cost
  • Less overall weight
  • Proven and patented systems
  • Less hydroynamic resistance, no underwater acoustic signature
  • Compact design due to high performance steering gear

From Idea to Proven Design

On early vessels equipped with rudder roll solutions the control, actuation and rudder equipment was supplied separately with the shipyard acting as the system integrator. In order to obtain the necessary rudder response, RH Marine’s patented control algorithms required the response characteristic of a rotary vane actuator resulting in the selection of a SKF Marine hydraulic power supply and vane actuator system, powering a Becker Marine King Support rudder.

In 2002, RH Marine, SKF Marine and Becker Marine decided to offer a rudder roll solution jointly and the first Consortium Agreement was signed between the three companies for the RRS system supplied to Republic of Korea Navy “Sejong the Great“ Class destroyers. The relevant equipment supply and interface responsibilities are now well established within the Consortium enabling a seamless RRS solution delivery by RH Marine.


To date, 9 different naval vessel rudder roll system solutions have been supplied, for 36 vessels currently in service and under construction.

  • Royal Netherlands Navy, 2 Karel Doorman Class frigates (M-Class)
  • Belgium Navy, 2 Karel Doorman Class frigates (M-Class)
  • Chilean Navy, 2 Karel Doorman Class frigates (M-Class)
  • Portuguese Navy, 2 Karel Doorman Class frigates (M-Class)
  • Royal Netherlands Navy, 4 De Zeven Provincien Class frigates (LCF)
  • German Navy, 3 Sachsen Class (F124) frigates
  • German Navy, 5 Braunschweig Class (K130) corvettes
  • Republic of Korea Navy, 3 Sejong the Great Class (KDX III) destroyers
  • Republic of Korea Navy, 4 Landing Ship Tank (LST-II) program
  • Republic of Korea Navy, 1 Mine Layer Ship (MLS-II)
  • Republic of Korea Navy, 7 Incheon Class (FFX-2nd Batch) frigate program
  • Republic of Korea Navy, 1 Advanced Traning Ship (ATX)
  • Royal Thai Navy, 1 DW3000F frigate

Customers experience

Objectives were to prove that ASSA meets navy requirements for roll motion and course control and to prove that all systems are fully operational in rough conditions.

‘Significant roll reductions up to 60 % were measured during the trials. Higher reductions could not be expected in given conditions. The ASSA system is fully operational in rough weather conditions, and adapted well to changes in speed and heading. Moderate rudder rates and amplitudes were demanded. Yaw motions and ship speed did not decrease using the Rudder Roll control. The course keeping is well within specifications.’

(Royal Netherlands Navy Report SB 8749)

Contact us

For more information about Defence, Safety & Security: 

Harm Kappen

Harm Kappen

Director Global Sales DSS

+31 10 4871590

This RH Marine website uses cookies for example to improve and analyze the website, for social media and to ensure that you see relevant ads. To learn more about cookies, click on Cookie Policy. When you click on accept, you authorize RH Marine to use the cookies as set for our website.