Design and engineering consultancy Longitude has introduced an advanced, live mooring line tension monitoring system for FPSO operations, securing its first contract with an undisclosed oil and gas operator.

The newly developed system – named Proper Live Load (PLL) – is designed to continuously monitor the real-time tension of the mooring lines on floating offshore units.

Undetected mooring line degradation or failure can lead to catastrophic consequences including high offsets, riser damage, production shutdown, and environmental incidents. Despite this, traditional monitoring approaches often rely on load cells which deteriorates in time and are not replaced, periodic inspections and disconnected data sources, leaving operators with limited real-time visibility.

“We address this gap by providing an always-on monitoring platform that combines real-time sensor data with predictive analytics and comprehensive integrity management — enabling operators to shift from reactive to proactive mooring management,” says Icaro Reis, naval architect and marine engineer at Longitude.

Real-time monitoring

The PLL-system can ingest data from geo positioning sensors available on board the floater. It then processes this data through a representative mooring analysis model, calibrated via retrofitting process with ROV UWILD inspection data and as-laid line conditions, to deliver real-time tension calculations, excursion tracking, and alarm generation.

The AI-driven system’s core capabilities include:

• Position and excursion monitoring: Continuous tracking of vessel position relative to operational and alarm watch circles.
• Mooring line tension monitoring: Real-time tension estimation using a validated mooring model, with optional integration of physical load cells for cross-validation.
• 6-degree-of-freedom (6DOF) motion monitoring: Full vessel motion tracking (surge, sway, heave, roll, pitch, yaw) through combined GNSS and inertial data.
• Structured alarm system: Multi-level excursion alarms, mooring line loss detection, abnormal tension pattern alerts.

“The PLL-system also integrates wind, wave and current data with historical operational records and machine learning models to predict vessel and mooring line behaviour under forecast conditions, supporting proactive decision-making. Additionally, tension history analysis of mooring lines combined with real-time fatigue tracking allows us to anticipate inspection or replacement needs,” adds Icaro Reis.

First contract

An undisclosed South American oil and gas operator has appointed Longitude on a one-year contract to utilise the Proper Live Load software on board one of its FPSOs.

“PLL represents an important step in the development of new mooring monitoring technologies, combining our deep expertise in naval architecture and offshore engineering with advanced digital tools. Its first deployment validates our vision of a fully integrated, intelligent monitoring platform for the offshore industry,” says Guilherme Leal, Longitude’s operations director for the Americas.

Longitude is the design and engineering branch of Oslo-listed consultancy group ABL Group ASA. Longitude Brazil integrated the Brazil-based naval and marine engineering specialists Proper Marine.