Meeting the lofting specialists in Cherbourg

Manual labor, mathematics and advanced software

The scent of wood fills the air, lending the room a calm, reassuring atmosphere. On the right, an initial model of a structure with massive, rounded forms, cut into small honeycomb-like cells, looks almost like a designer bookcase. Further on, templates, compasses (pinnules), rules and marking gauges lie waiting on the floor. Before the digital age, it was here that submarines first took shape, entirely drafted in wood. At the time, no less than forty lofting specialists worked here. Today, there are seventeen, along with two carpenters. Computer-aided design (CAD) has supplanted hand-drawn plans, but manual manufacturing remains. “We have kept both facets of the profession,” explains Maximilien Thomas, Head of the Methods and Production Engineering Department for hulls and structures. “We design and manufacture three-dimensional templates (weighing up to one tonne) and ‘blason’ templates (lighter and easier to handle) to help production teams with plate-forming operations and quality control. In addition, manufacturing full-scale models is extremely useful for validating certain design choices. We have just completed one that will also be used by our customer, the French Defence Procurement Agency (DGA), for training and evacuation exercises. Whether small or large, we are responsible for the entire design and manufacturing process for every piece we supply – a rather unique feature of our work, and one that I find fascinating,” he adds. No specific training program leads directly to the lofting specialist profession. Those who enter the field often have boilermaking backgrounds. They are not initially familiar with wood, cutting or chamfering machines, or carpentry tools. Over time, they must develop manual skills while also mastering CAD software. Achieving full autonomy as a lofting specialist requires five years of constant and patient mentoring, provided by the most experienced members of the team, whose expertise often exceeds ten years. Recruitment is currently under way to strengthen the team, driven by new programs for both France and international customers. In the meantime, the team must also be ready to handle unexpected situations. “After the fire onboard the nuclear attack submarine (SSN) Perle, we were asked to produce a model of an intermediate section to support the cable splicing operations required when joining the forward and aft sections of two SSNs,” explains Maximilien Thomas. Assignments range from a few hours to several months of work, which means the lofting team never lacks variety. As a result, downtime is rare among the lofting specialists, who share a remarkable team spirit across generations.

How can a wooden model optimise the reactor of the future third-generation SSBN?

Last October, Naval Group and TechnicAtome, responsible for the design, construction, commissioning and in-service support (ISS) of the onboard nuclear reactors, carried out tests with representatives from the French Defence Procurement Agency (DGA) and the French Navy. The tests took place in a full-scale wooden model of a compartment from the future third-generation ballistic missile submarine (SSBN 3G), outfitted by TechnicAtome.

For Margaux Baechel, Human Factors Technical Lead on the program at TechnicAtome, “Putting future users in a full-scale mock-up is part of a user-centred design approach. It allows us to anticipate how they will work and to analyse the movements and postures they will adopt. If access is difficult, we can quickly test optimisation options with all participants.”

Jean-Loup Noël, Head of Reactor Room Outfitting for TechnicAtome, emphasises the complementarity with digital modelling: “Most options were already validated using computer-aided design (CAD). The wooden model confirms our choices and validates the interventions and operations planned for construction and operational use.” The model also restores a sense of spatial volume, sometimes lost in simulations. For the sailors, it was a revelation to see the maturity of the studies through this model, more than ten years before the first third-generation SSBN enters active service.