The Passive Damping System supplied by SEH works in conjunction with the davit system and the ARRC as a safety device. It prevents the possible build up of harmonic oscillations when the ARRC is suspended from the davit falls during its deployment from and recovery to the RSV.

The ARRCs are crewed when they are deployed and recovered using the davit system so any oscillations that were to occur could cause damage and be unsafe for the crew. SEH have conceived, designed, manufactured, supplied, installed and commissioned eight Passive Damping Systems onto four RSVs for use with eight ARRCs.

Each Passive Damping System consists of a hydraulic power unit, a pair of mechanical arms that provide a force onto the inflatable sponson of ARRC, pipework and the necessary electrical controls.

Once the damper arms are deployed, the system is designed so that no power is used to provide the damping force on to the sponson of the ARRC. This means that in the event of a failure of vessel power whilst the ARRC is suspended from the davit falls, the damping arms can continue to provide the damping force until power is restored, meaning that the ARRC crew are protected from any build up in oscillations that may occur.

SEH first looked at the requirement in June 2006 and by October 2006 were factory testing the system prior to commencing installation in November and commissioning the first RSV, Caledonian Vigilance, in mid December. The other three RSVs were installed between January and April 2007.