Designing Acapella: How Orca3D Supported Stability and Performance Analysis on a 49-Meter Sailing Yacht 

Designing a 49-meter sailing yacht is rarely about optimizing a single variable. Hull geometry, stability, propulsion, accommodations, classification requirements, construction, and aesthetics all have to work together. 

For naval architect Srđan Đaković, that challenge came together in Acapella, a 49-meter luxury sailing yacht developed between 2019 and 2021. 

The principal dimensions and overall design direction were well established early in the project. But as the design moved toward classification and construction, even relatively small changes had to be evaluated carefully. One such refinement involved the yacht’s beam. 

To ensure full compliance with the stability requirements of the Croatian Register of Shipping (CRS), Srđan made adjustments to the beam and used Orca3D Real-Time Hydrostatics and stability analysis to understand and verify the effects of the change. During the refinement process, he could quickly check important hydrostatics and stability parameters directly from the evolving Rhino geometry.  

Rather than using analysis to search for an entirely different hull concept, Orca3D became a practical tool for refining, checking, and confirming an already well-defined design.

49-meter luxury sailing yacht Acapella docked at night 

Designing Acapella 

Acapella was conceived as a luxury sailing yacht with the proportions and character of a classic cruiser, but with the engineering, safety, comfort, and performance expected of a contemporary vessel. Key specifications include:

The owners wanted more than the appearance of a traditional sailing yacht. According to Srđan, they wanted Acapella to have genuine sailing capability while meeting the applicable CRS requirements for a sailing vessel.  That put stability at the center of several important design checks. 

From MultiSurf to Rhino and Orca3D 

Acapella’s digital development followed a workflow Srđan has used on several vessel projects. The initial hull form and surfaces were developed in AeroHydro/MultiSurf. This use case emphasizes the fact that the analysis tools within Orca3D do not require that the geometry model was created with Orca3D, or even created in Rhino. As long as the geometry can be imported into Rhino as surface or mesh geometry, it can be analyzed with Orca3D. Subsequent design development and refinement took place in Rhino using Orca3D for naval architecture calculations including hydrostatics, stability, resistance, propulsion, and performance evaluation.  

This distinction is important: Orca3D was not used to generate Acapella’s original hull concept. Instead, it gave Srđan a way to evaluate the engineering consequences of refinements as the design progressed. 

“For the Acapella project, Orca3D proved to be a practical and reliable engineering tool. Its integration with Rhino made it easy to verify hydrostatics and evaluate design changes efficiently throughout the development process.” 

Acapella sailing yacht hull geometry model used during design development 

Refining the Hull to Meet CRS Stability Requirements 

The overall hull geometry and principal dimensions were largely established from the outset, so Acapella did not require a series of major hull-form redesigns.  But classification still required careful verification. 

One of the specific refinements involved adjustments to the yacht’s beam to ensure full compliance with CRS stability requirements. This is where Orca3D’s interactive workflow became particularly useful. 

As Srđan refined the geometry, Real-Time Hydrostatics allowed him to monitor characteristics including: 

• displacement,  
• trim,  
• center of buoyancy,  
• and stability.  

Instead of modifying geometry, exporting the model, running an analysis in a separate application, and then returning to the design environment, the hydrostatic information could be evaluated alongside the Rhino geometry. 

“Orca3D’s real-time hydrostatics were used to verify displacement, trim, center of buoyancy and stability as the geometry was refined. The hydrostatic analysis was primarily a verification and refinement tool rather than a means of exploring fundamentally different hull concepts.” 

Rhino 3D model of the 49-meter Acapella sailing yacht 

Verifying Stability for a True Sailing Yacht 

The stability requirement was especially important because Acapella was not intended simply to resemble a traditional sailing vessel.  The owners expected the yacht to sail. That meant the naval architecture had to support the vessel’s sailing mission while satisfying the relevant CRS classification criteria. 

Srđan used Orca3D primarily for hydrostatics and stability analysis, checking the developing design and making the adjustments needed to meet those requirements. Resistance and propulsion prediction were also used.  The role of the software was to help him answer a simple question: Does the design we want to build perform as intended and satisfy the engineering requirements placed on it? 

For Srđan, Orca3D provided an efficient way to answer that question before committing the design to construction.  

Transparent 3D model showing the internal arrangement of Acapella sailing yacht 

Using Speed & Power Analysis to Support Engine Selection 

Acapella also provides a useful example of how resistance and propulsion prediction can support a project even when hull optimization is not the primary objective. 

The yacht was designed as a classic cruiser rather than a racing yacht, and its desired cruising performance was established early in the program. As a result, Srđan did not use resistance prediction to drive major changes to the hull form. 

Instead, Orca3D’s resistance and propulsion prediction tools were used to estimate the power required to achieve the intended performance and support selection of the main engines.  

The final vessel is powered by two 600 HP John Deere engines, with a reported cruising speed of 12 knots and maximum speed of 15 knots. 

That distinction reflects a practical engineering use case for performance prediction: sometimes the goal is not to continuously reshape a hull in pursuit of the lowest possible resistance. Sometimes it is to confirm that an established vessel concept and propulsion package are appropriately matched. 

Profile rendering of Acapella sailing yacht used during naval architecture development 

From Digital Model to Steel Construction 

The engineering analysis ultimately had to translate into a real vessel. Acapella’s hull and superstructure were constructed in steel, turning the geometry developed digitally into a 49-meter vessel capable of accommodating 12 guests and a crew of nine. 

Steel hull of the 49-meter Acapella sailing yacht under construction  

From Model to Finished Yacht 

Acapella was completed in 2021. The finished yacht reflects the design intent established at the beginning of the program: a large cruising sailing yacht with traditional proportions, substantial guest accommodations, genuine sailing capability, and compliance with contemporary classification requirements.  But the engineering story behind the finished vessel is less about a dramatic redesign than it is about confidence in a series of decisions. Srđan summarized Orca3D’s role this way: 

“Orca3D helped us quickly check different design options and confirm our decisions. Its calculations gave us a clear picture of the vessel’s performance and helped us move forward with confidence.”  

That may be one of the more representative measures of value in a naval architecture workflow. Not every project requires a radical optimization study. In many cases, the challenge is being able to refine an established design, verify the engineering, satisfy classification requirements, and move confidently toward construction. 

Photo of the completed Acapella demonstrates the transition from hull geometry and engineering analysis to a fully realized 49-meter sailing yacht.  

A Workflow Applied Across Different Vessel Types 

Acapella is not the only project where Srđan has used this workflow. 

The yacht carries a SuperRIB 30 tender, which he also designed. According to Srđan, Rhino and Orca3D played an even larger role in that vessel’s development, supporting hull optimization, hydrostatic calculations, and performance analysis. 

The two projects are very different in scale and mission, but both illustrate the value of keeping geometry development and naval architecture analysis closely connected. 

For Srđan, that combination has become a repeatable workflow: develop and refine the geometry, evaluate the engineering implications, and use the analysis to confirm that the vessel performs as intended. 

Engineering Confidence Without Leaving the Design Workflow 

Acapella demonstrates a practical side of integrated naval architecture software. Orca3D did not determine what the yacht should look like, nor did it replace the judgment of the naval architect. Instead, it allowed Srđan to evaluate the design he wanted to build. 

A small beam change could be checked against hydrostatics and stability goals. CRS requirements could be evaluated during design refinement. Resistance and propulsion calculations could confirm the power required for the yacht’s intended operating profile. 

And those calculations could be performed while continuing to work with the vessel geometry in Rhino. 

For a project like Acapella, the result was not simply a set of analysis reports. It was a more efficient way to verify design decisions and move the project toward construction with confidence. 

Bring naval architecture analysis into your Rhino workflow. 

Explore Orca3D tools for hull design, hydrostatics, stability, speed & power prediction, weight management, and Marine CFD.