3000m Mid-Depth System

LARS Launch from the CCGS Hudson This system was designed as a self contained launch and recovery platform with an operating depth of 3000 meters. It uses a 30,000 Lbs (13,636 Kg) LARS (Launch and Recovery System) and a 33,150 Lbs (15,068 Kg) umbilical winch to safely and efficiently deploy the vehicle with minimal crew requirement.

This system offers several advantages

Increased sea-state operations. The crane uses a passive heave compensation mechanism and can be mounted at mid-ship where the effects of the ship's heave are greatly reduced. Provided the vessel can hold station, ROV operations can continue in sea states 5 to 6.
Minimal ship's crew requirements. The LARS allows us to get close to the water and securely latch the vehicle without the use of tag-lines. Typically two members of the ship's deck crew are all that is required for launch and recovery.

LARS Launch from UNOLS T.G. Thompson

4000 lbs through-frame lift. This system allows the vehicle to be used to recover or deploy heavy packages to a depth of 3000 meters. This ability is unique to the ROPOS mid-depth system and has been successfully used to recover instruments weighing in excess of 2000 lbs and is the backbone of the ROCLS sub-sea cable laying system.

Through-frame lift used for instrument recovery
Through-frame lift fitted with ROCLS System

Ship independent. With several mounting configuration and no need for a ship's A-frame, this system can be shipped and adapted to vessels all around the world. Moreover, this autonomy frees up deck equipment which allows the science party to perform other science ventures that could not have previously been possible with an ROV onboard.

Details and Drawings

LARS Details

The LARS is designed for the ROV tether to feed through the pedestal to the turret center sheave and then to the docking/swing frame. This is accomplished by using the UNOLS AGOR style turret, which is higher than the standard 18 ton style. The turret is further modified to allow the use of longer lifting cylinders, which helps the lifting capacity of the crane, while maintaining 86 deg. boom articulation, without contacting the turret structure. Since the cable is centered on the LARS's rotation axis, the crane can slew up to 360 deg during handling operations. The pedestal sheave is designed with 10 deg of flagging or fair-leading capability. The pedestal and turret sheaves are designed with split block bearing mounts for removal during mobilization and shipping.

LARS mounting requirements

Past ROPOS LARS installations have used existing crane bases fitted with adapters to suit individual requirements (CCGS Hudson). With the addition of the LARS base deck adapter system, the LARS can easily be mounted directly to the working deck of the vessel by way of either directly bolting to an existing deck (UNOLS Thomas G. Thompson) or by fitting a welded doubler plate directly to the deck (CCGS J.P. Tully). The LARS’ outboard range can be limited to decrease its turning moment and allowing for fitments in areas where the maximum turning moment of the LARS exceeds the safe working load of the ships structure.