The function of a gyroscopic fin stabilizer, found on both sides of a ship’s hull, is to provide resistance to the excess rolling of a ship, in either direction.

The fins are designed to vary in tilt to counteract roll and are retractable when their assistance is not required, or the vessel is arriving in port.
ATZ with our partner Aegir Marine have the parts, service and experience to overhaul many Stabiliser types. We are maker independent.

Ship Stabilizer


Typically found on cruise ships or naval vessels these stabilisers assist the ship in cutting through the water more effectively, additional fuel used to carry the stabiliser weight is counteracted by a cleaner forward motion. The stabilisers are especially useful in rough sea conditions with high waves and strong wind, helping maintain passenger satisfaction.

The fin’s sensitive gyro system senses the rolling motion of the ship and sends a signal to the actuating system which, in turn, causes the fins to move in a direction such as to cause forces opposing the roll. The actuating gear is usually electrohydraulic.

The stabiliser arrangement on a vessel normally consists of the following equipment:

  • Two fins that form part of the hull structure of the vessel, one port and one starboard.
  • The fins are connected to a fin stabilizer room on port and starboard sides from where they are operated/ controlled
  • Each stabilizer has a fin box, which houses the fin and supports the fin actuating machinery. 
  • The fin actuating machinery provides the support and the means by which the fin may be rigged in or out (extended or retracted), locked and typically tilted up to +/-25 degrees.
  • Hydraulic power packs on each stabiliser arrangement to control the hydraulic circuits that allow rigging and titling of the fins.

Most planned maintenance on fin stabilisers centres around the hydraulic system and fin box with a typical scope of work including:

  • Replacement of hydraulic system hoses, seals and valves
  • Replacement of rigging and tilting seals
  • Refilling with new oil
  • Inspection of the rigging cylinder
  • Inspection and crack repairs in the fin box. This area of the hull is highly stressed as it reacts to the forces imparted by the fin when controlling roll.
  • Blasting, cleaning and painting of the fin box
  • Testing of stabiliser and calibration of fin tilt
Propulsion Overhaul

More comprehensive maintenance can be carried out as and when equipment condition demands it, but may include:

  • Removal of the fin for inspection of the tilting shaft and replacement as necessary
  • Replacement of the rigging cylinder. Due to the size and weight of this component typically a hole is cut in the ship’s hull to allow removal and insertion of a new cylinder.

ATZ with our partner Aegir Marine have extensive experience with most stabiliser types are in position meet your parts and service needs. 

Stabiliser repairs are normally carried out at the shipyard.


Can the stabiliser hydraulic system be repaired whilst afloat?

Yes, most of this equipment can be accessed from one of the machinery spaces inside the vessel.

Can a Stabiliser operate on a biodegradable oil?

This is largely dependent on the components that are most likely to be affected by the bio oil (particularly when mixed with seawater), and are normally elastomeric (gaskets, o rings, lip seals etc). It is essential that they are of a compatible material. 
Many stabilisers are bio compatible or can easily be upgraded to be so.

Where are stabilisers located?

As previously mentioned, there is one on each side of the ship, placed centrally below the waterline in order to secure maximum leverage for the forces acting upon them.

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