Dynamic Load Monitoring (UK) Ltd. (DLM) from Southampton, UK, has supplied eight bespoke Running Line Monitors (RLMs) for Jan de Nul’s 236.8 m long Les Alizés, a next generation floating installation crane ship with a 5,000 t capacity to be built in China.

DLM, a specialist in the design, manufacture, repair and calibration of load cells and load monitoring devices, supplied the RLMs to NOV’s BLM division, which designs and manufactures marine and offshore equipment products. NOV-BLM asked DLM for the equipment to monitor the tension on mooring winches on board the Les Alizés.

The solution is an 8-point mooring system that locks the ship in place and keeps it stable during operation. The original performance criterion was 0-2750 kN, which was later changed to 3,500 kN (approx. 350 t). DLM decided on a tailor-made solution based on its standard RLM with a nominal power of 200 t and adapted to a larger rope diameter as well as increased requirements for the safe working load (SWL) and the minimum breaking load (MBL).

Jamie Woodcock, Business Development Manager at DLM, said, “The originally specified workspace has been improved by the customer. The calibration was also a challenge due to the high workload and test load requirements. We tested a safe calibrated load using a wire rope and then tested the pen in a compression machine to simulate the resulting load that the pen would see in operation. This eliminated the need for risky and potentially unsafe wire rope tests for this very high tension [5,000 kN]. ”

Woodcock added, “By making the frame bigger, we could use bigger wheels to match the 76mm diameter rope. We also had to improve some components for the higher SWL, but still kept a high safety factor. “

Other outstanding features of the RLMs were a maximum design speed of 30 m / min up to 200 t, then 15 m / min; Test load 1.5 x SWL, which corresponds to a line tension of 5,625 kN; and high repeat accuracy up to the full working scale. The calibration process required multiple 76mm slings as each RLM had to have multiple runs. The device is powder-coated in gray according to the customer-specific RAL reference and is suitable for the marine environment with a service life of more than 20 years. After-sales support is also offered as part of the contract.

Woodcock said, “The marine and renewable energy industries are very busy. Jan de Nul will likely use this ship for construction projects such as installing large offshore wind turbines. “

The standard RLM range from DLM (15 t, 60 t, 200 t) has been specially developed for harsh marine-type environments. Typically used in laying, towing, mooring, and other winching operations to measure and record line tension, payout, and speed. Its robust design makes it the perfect line voltage monitor for demanding offshore applications. Available in wired or wireless configurations, they can be integrated into existing marine systems or supplied as stand-alone systems with single or multiple input HMI displays, as well as touchscreen and data logging capabilities.

Jan de Nuls Les Alizés will be completed in 2022.