Internship - Hydrodynamics Engineer

Purpose

Topic : Mooring system fatigue analyses 

6 months internship based in Monaco 

Introduction: 

Main types of mooring systems are Single Point Mooring (vessel weathervanes about a fixed part like a turret) or spread mooring (fixed vessel heading, unit is generally moored by 4 bundles of mooring lines, one per corner). See figures below.

One of the design criteria of mooring systems is fatigue of the mooring components.

Fatigue (damage on mooring lines) is induced by tension variations in the mooring line over service life and some contribution arising from in-plane and out-of plane bending stresses on chain links. For turret moored systems, those tension variations on mooring lines also results in loading that serve to design turret structure in fatigue (turret loads)  

Fatigue is studied versus a long-term description of the environment (scatter diagrams, hindcast data) generally involving a large number of environmental combinations between wind / waves and current. It is often not realistic to run all these combinations in time domain to get their contribution to total damage. Methods are often used to reduce sample size of the environmental combinations from which total damaged will be established.

Several of these methods are widely used and accepted across the industry. In December 2024, DNV introduced “importance sampling” in DNV-OS-E301. This method has already been benchmarked for a spread-moored project and compared with alternative approaches.

The internship aims to further assess the suitability of importance sampling for a turret-moored project and to help establish best practices for mooring fatigue analyses

Responsibilities

Description 

The internship will cover two main steps:

1. Review and summarise the DNV-OS-E301 requirements and the “importance sampling” method, then compare it with other recognised methods.
2. Apply the importance sampling method to at least one representative turret-moored project.

• • Compare the results with those obtained using other approaches based on representative year(s).
  • Evaluate the method’s suitability for out-of-plane bending analyses.
  • Determine whether the method can be extended to turret-load analyses, ensuring a consistent approach for the mooring lines and turret.

3. If time allows, assess how the method could be implemented efficiently on projects, for example through a reusable workflow.

Your Role

• • Get a good understanding of the methods used.
  • Perform numerical analyses to find best modelling techniques. Interpret results.
  • Present conclusions to Hydrodynamics department.

What it will bring to you:

• • Exposure to engineering methods used in mooring design
  • Use of industry-recognized software (Ariane, Orcaflex)
  • Solid theoretical and practical background on mooring whichever field of applications (offshore, renewables …).

Education

• Engineering schools, 2nd or 3rd year
• Prior exposure to offshore industry, mooring is a plus
• Programming in Python (script to handle large data, to cluster data) is required