Bleu de Nimes Lengthening project


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Bleu de Nimes yacht before and after refit

Photos & images: Studio Nattero


Engineering project performed by Studio d’Ingegneria Mario Nattero of Genoa, Italy.

In 2014, Studio Nattero started to work on a major refit project for motoryacht Bleu de Nimes. Amongst other modification and updates to the yacht’s delivery, the project included modifications to the hull form,  with a full redesign of the stern to create a beach club, to the addition of a bulbous bow, and the lengthening by 11.7 metres of the central body of the hull. The benefits of such modifications are multi-fold, from increase of guest accommodation spaces to the addition of 2 tender garages at midship, to improved hydrodynamic performances (passenger comfort, increased speed, and reduced fuel consumption). During the transformation, the notation was changed from Commercial Yacht to Passenger Yacht. The new class was certified by the American Bureau of Shipping (ABS).

The lengthening of the central body of the hull and superstructure represented by itself an engineering & shipbuilding feat. For instance, the presence of 2 large tender garage shell doors at midship required an attentive assessment of the vessel’s longitudinal strength. To tackle the global structural challenges, the technical team at Studio Nattero relied on MAESTRO Marine, a finite element analysis (FEA) software, tailored for the naval architect, and hence integrating hydrostatics, and the modelling of all marine related loads such as tanks and wave profiles, static and dynamics thanks to sea-state models. The structural model is automatically balanced hydrostatically, in full accordance with the hydrostatic & stability software. A thorough weight model and distribution makes the FEA analysis totally realistic lending that extra level of accuracy to the study.

Geometrical model of tanks in MAESTRO Marine


Thanks to this hydrostatic balance, a comprehensive collection of loading conditions, weight and draft variations is applied to one same MAESTRO FE model, further subjected to several static wave amplitudes and headings, etc. and solved in a single run.

Looking at more local structure, Studio Nattero’s engineers were able to also design and integrate crane foundations and tender garage’s shell doors by refining the FE mesh as required to represent highly stressed details, thereby solving a single, combined fine-coarse mesh model.



Annalisa Bracco, Project Manager at Studio Nattero:

Within the structural assessment of such an extensive and complex project, we have appreciated the flexibility and power of MAESTRO Marine, which allowed us to apply to modelled geometries dozens of different loads, inclusive of tanks derived from Stability software, wave profiles and local actions related to crane operation. Same base Maestro geometry has “grown” with the project, with the introduction of new parts such as bulb and aft platform and allowed us to evaluate global and local structural behaviour of the unit in a wide range of different scenarios, including a possible launch of the unit by crane and operation of large tender side doors. Outcomes obtained by Maestro analyses have allowed us to communicate with Authorities involved in the project with no effort nor additional post-processing”



MAESTRO is a design, analysis, evaluation, and optimization tool specifically tailored for water-bound structures, and has been fielded as a commercial product for over 30 years with a world-wide user base. MAESTRO’s history is rooted in rationally-based structural design, which is defined as a design directly and entirely based on first principles and computer-based methods of structural analysis (e.g., finite element analysis and structural limit state evaluation). At MAESTRO’s core is a structural design tool developed to suit the needs of ship designers and naval architects.

MAESTRO Marine is distributed in EMEA by NDAR.


Established in 1988, NDAR offers a full range of synergetic Naval Architecture, Design, Production and PLM software, such as GHS, MAESTRO, ShipWeight, ShipConstructor, Rhino3D and its marine plug-ins Orca3D & ExpressMarine, AutoFEM, etc.  as well as naval architecture & marine engineering advanced services.  The range of expertise offered by NDAR and its industry partners covers the full ship, workboat, yacht, and offshore industry spectrum.


Studio d’Ingegneria Mario Nattero

Studio Nattero is an independent international design and engineering company for the maritime industry which assists ship-owners, contractors, shipyards, authorities, and other design companies in realizing their designs. Studio Nattero operates in every niche market presenting an opportunity to improve, innovate or invest. All developments at Studio Nattero aim for what customers need and what they wish for, from feasibility studies to engineering, project management and special operations.


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