50m M/Y Thanuja successfully completes sea trials after extensive rebuild.

M/Y Thanuja will be soon delivered to her owner and will be available for charter in the Mediterranean throughout the upcoming summer season.

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50m M/Y Thanuja successfully completes sea trials after extensive rebuild.


Originally built in 2011 by Concept Marine in Turkey and named M/Y Greyzone, the superyacht underwent an extensive rebuild at Serenity Yacht. A huge overhaul included stripping down the vessel to bare metal, extending stern and aft decks and upgrading the flybridge.
This ambitious endeavor resulted in a remarkable increase in volume, from 380 GT to 440 GT, and a substantial growth in length: from 38 to 50 meters. Notably, the classification society, along with all stakeholders, recognized this transformation as equivalent to a new build: a new superyacht holding a new name: M/Y Thanuja.

iYacht GmbH, the German one stop yacht design & engineering firm, was responsible for the exterior design and naval architecture on this ambitious rebuild.

Commenting on the project, Udo A. Hafner, CEO of iYacht GmbH, stated,
M/Y Thanuja holds a special importance for our studio. During the last 12 months, we have successfully delivered a wide range of projects, ranging from electric outboards to 50m superyachts, from sailing monohulls to power catamarans.
Thanuja initially began as a simple refit but quickly evolved into a major conversion. Leveraging the many expertise of our studio we were able to support the owner and the yard in every phase. As the project complexity grew it required us to bring in additional expertise from different disciplines.
We are proud to have been an integral part of this project, from the initial concept, exterior design, naval architecture”

The Hamburg and Kiel based firm is able to offer the full range of services, from initial sketch to CE marking. This holistic approach is particularly appreciated during refits and rebuild projects, where starting from an existing vessel may bring to the table new unknown variables, not easy forecastable before further examining the starting vessel.

As soon as the refit transitioned into a rebuild, and new unknown and technical challenges needed to be solved, the owner relied on the in house expertise of iYacht instead of involving more people to the project, which would have led to more interfaces, burden the project coordination, and ultimately ending up with a significant time and cost increase.


An extensive refit, considered as a new build

The starting point for this project was to reverse-engineer the existing superyacht.
In June 2020, iYacht’s team flew to the south of France to measure and create an accurate 3D model of M/Y Greyzone, combining state-of-the-art laser distance measuring with several methods.
Over the years, the iYacht team has perfected this initial process, conducting numerous 3D scans for significant projects, including the 141-meter-long M/Y Yas. Getting this measurement right was the foundation for reshaping the bow of this iconic superyacht.

These CAD models were the foundation on which the design team of iYacht drafted the first sketches aligned with the owner’s brief. Only four weeks later, the first concepts were available.
iYacht’s proposed solution encompassed a new galley, a substantial overhaul of the foredeck, the addition of a jacuzzi on the flybridge, and an extension to the stern bathing platform.
A large Z-lift was to be implemented, which gave the opportunity to completely redesign the beach club.
This area, ensuring seamless connection with the sea, has become increasingly important in yacht design, and its redesign was a key element in bringing a 2009 vessel into a superyacht with a modern aesthetic.

Merely three months after the initial inspection, the iYacht team presented a meticulously detailed plan outlining the tasks necessary to successfully accomplish the refit.


As the refit commenced, a comprehensive analysis of the superyacht prompted the team, ranging from the owner’s representative to the project manager, to expand the refit’s scope. The decision was made to rebuild the 2009 Greyzone into a state-of-the-art 50m superyacht built to North European standards.

The technical spaces underwent a complete reconstruction: a new engine room, new bow and stern thrusters, along with the installation of new pipes, cabling, engines, and generators. Structurally, the aluminum superstructure, including the flybridge roof, underwent meticulous re-welding. These modifications resulted in a 8-meter lengthening of the yacht.

Internally, the superyacht underwent a transformation with the complete replacement of the teak decking, as well as the introduction of new interior and exterior furniture. This ambitious task was expertly executed by Katharina Raczek and her team. Working in collaboration with the shipyard’s interior fitters, they formed a task force that worked both as creative inventors and as problem solvers, addressing challenges arising from the interfaces between pre-existing areas and new construction.
After these upgrades, now M/Y Thanuja can comfortably accommodate up to 10 guests in 5 staterooms and a crew of 7 across 6 rooms.

A rebuild is inherently more intricate than new construction, as it introduces constraints in many fields: design, engineering and also manufacturing.
From a design point of view, the resulting challenge is to find the delicate balance between the new and the old elements. The new owner brief must be met starting from an existing yacht that was the result of the previous owner’s brief, which may be radically different.
Aesthetically, the changes must align harmoniously, respecting compatibility with the existing design.

From a technical standpoint, the challenges intensify further, as modifications and upgrades must consider pre-existing conditions, including materials, elements, and old equipment. This necessitates a creative and innovative approach to both engineering and manufacturing.

Last but not least, when rebuilding a superyacht, the new vessel must comply with current regulatory standards, which have notably increased in safety, environmental, and operational regulations over the last 10 years. iYacht was also responsible for coordinating with the classification society to ensure the certification of this superyacht.


Hamburg – Antalya Teamwork

Stefan Zucker, founder of yacht consultancy firm Zucker & Partner, played a crucial role in coordinating the project. The owner provided an experienced project manager who was permanently present on site at the shipyard, which proved to be extremely helpful. 

The shipyard was specially adapted and equipped for the project: Serenity Shipyard built a competent and flexible team around this mammoth task, around 100 employees were simultaneously busy with the tasks of the new building. The interior was given an unequally high level of importance so there was no longer any need to think about necessary cosmetic repairs, but rather a complete redesign. 


iYacht executed the designs and detailed production plans using 3D models ready for manufacturing, complete with bills of materials. Hafner and his team were responsible for the details of the metal construction, technical installations, and class plans.

Coincidentally, Hamburg was the home base of everyone involved in the project, but the central meeting point was always the shipyard in Antalya.

Following this comprehensive rebuild, M/Y THANUJA met the high-quality standards of the superyacht industry in every field: from technical installations and systems, to the structure and external and interior design.
The crew cabins have been expanded, and the superyacht received approval for commercial charter under the Luxembourg flag and will certainly set a benchmark in her class on the charter market. 

Tens of thousands of hours of coordination, planning, and engineering were essential to the success of this rebuild. In the end, the investment of time and effort unquestionably paid off, successfully transforming a 2009 superyacht into a 50m superyacht that adheres to North European standards.