Trailing Arm Pre-and-Post Trenching
Our OCS Utility Barge UB-01 ‘Miss Pennie’ can be equipped with a purpose-built Trailing Arm Trenching System designed for both pre- and post-lay trenching of subsea pipelines. The trailing arm measures 31 metres in length, 3.5 metres in width, and 2.5 metres in height, with weight of 18 metric tonnes (mT). Engineered for versatility and reach, the arm is capable of a maximum rotation angle of 80 degrees and is able to operate in water depths of up to 28 metres (accounting for a pivot rotation point positioned 2.3 metres above sea level). This range enables efficient trenching operations in shallow to medium water depths, while maintaining the manoeuvrability and stability required for controlled excavation and backfilling.
For pre-trenching activities, the trailing arm is fitted with a robust dredging head measuring 3.2 x 4.2 x 2.1 metres and weighing approximately 10mT. This head is designed to displace seabed soil ahead of pipe installation.
In post-lay operations, the system switches to an articulated jet sled outfitted with modular nozzle configurations to match a wide range of pipe diameters—from 8 inches up to 52 inches. The nozzle assembly measures 6.0 x 3.9 x 1.1 metres and weighs approximately 3.5mT. The flexibility of the jet sled allows it to adapt to different pipe sizes through four distinct nozzle configurations, making the system suitable for a wide range of offshore pipeline scopes.
