ROV Launch and Recovery Systems (LARS)
 

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LARS, TMS and ROV

The essential elements of an ROV Launch and Recovery System (LARS) are:

An umbilical winch with sufficient capacity to accommodate the maximum length and diameter of ROV umbilical that the system requires. The winch will normally be fitted with a level wind mechanism to ensure even spooling of the umbilical cable onto the winch drum. A hydraulic winch motor is installed in the winch that is suitably sized to cater for the size of winch drum selected as well as the weight of the deployed ROV and TMS together with the umbilical weight and any dynamic amplification factors to be applied to the design.

Winch and level-wind mechanism		Example of LARS controls

Slip Ring. An appropriate slip ring with sufficient passes to match the conductors required in the umbilical needs to be specified and to be installed in the winch drum.

'A' Frame or Crane. A mechanism is needed to lift and overboard the ROV. This can be a crane or 'A' frame suitably rated to accommodate the maximum weight to be deployed including the weight of umbilical in air or water, (whichever is greater), and the applied dynamic amplification factor specified which is usually 3G. For self contained packages, 'A' frame systems are generally preferred and in the standard Saab Seaeye range these include an elevated pivot point to allow clearance of the ROV and its TMS over the ship's side or guard rails. Due to their smaller footprint, Crane LARS can be used when deck space is at a premium.

'A' Frame showing elevated pivot point

Sheave. A sheave wheel is fitted to the crane or 'A' frame of greater diameter than the minimum bend radius of the ROV umbilical. For safer handling it is recommended that the optional lock latch mechanism be incorporated with the sheave wheel to capture the ROV (or TMS) bullet during over boarding and recovery.

Sheave and lock latch		Sheave and snubber rotator

Hydraulic Power Unit (HPU). A suitably sized HPU is required to provide hydraulic power to the winch, 'A' frame rams and lock latch mechanism.

Mounting Skid. Although winches, 'A' frames and an HPU can be provided as stand alone units, for ease of transport and mobilisation, it is generally preferred to provide a complete LARS package mounted on a dedicated skid base that can be welded to the deck.

Integrated Winch, HPU and 'A' Frame LARS

The LARS can be specified for safe area or Zone 2 area operations. Zone 2 certification is generally required for drill support operations.

The minimum certification package generally required will include a DNV or Lloyds witness of the system load tests and this is provided as standard for all Seaeye LARS. Increasingly oil industry clients require DNV or Lloyds design approval for the LARS which will include their witnessing the manufacturing process. This is available as an optional extra cost and can cause some delays over standard delivery times particularly for custom designed systems.

SPECIFICATIONS MAY CHANGE WITHOUT PRIOR NOTICE