Choosing marine tools for Rhino 3D starts with the decisions your project needs to support. Developing a hull surface, comparing displacement, estimating resistance and assessing damaged stability are different tasks. A useful software choice connects the geometry with the right calculation method and a clear engineering deliverable.

Orca3D and Nemo both extend a Rhino-based marine workflow, but their organisation and emphasis differ. Rather than ranking them as interchangeable plugins, use the required analysis and the way your team develops models to decide where each fits.

Start With the Design Question

For an early hull study, you might need to compare displacement and hydrostatic coefficients across several forms. A performance study adds questions about speed, resistance and power. A stability assessment introduces loading conditions, centres of gravity, tanks and potentially damaged compartments.

Define those outputs before selecting software. Then record the inputs each calculation needs, who will maintain them and how results will be reviewed. This helps separate a convenient modelling function from a complete analysis workflow.

Hull Development and Hydrostatic Feedback

Orca3D’s Design module combines hull design and fairing with basic hydrostatics and stability. Load cases can be defined using a flotation plane or displacement and centre of gravity, then saved for later analysis. This suits a workflow in which hull refinement and repeated checks of floating condition develop together.

Nemo provides Grasshopper-based tools for sections, linesplans, hydrostatics and coefficients. Its Designer tools include parametric shapes such as NACA profiles, hydrofoils, keels, rudders, propeller blades and sail plans. Level 1 adds Section, Hydrostatics and Visualization; Level 1+2 adds Resistance and Structure.

The practical distinction is how you want to organise the work. Explore Orca3D when its hull-development tools and load-case workflow match your task. Explore Nemo when you want marine calculations and geometric outputs connected within a Grasshopper definition. Compare both against a representative hull rather than relying on a feature count.

Resistance Prediction: Choose the Method Around the Vessel

Orca3D’s Analysis module includes Savitsky, Holtrop and van Oortmerssen prediction methods. The developer associates these with chine hulls, displacement hulls, and tugs and trawlers respectively. Model-derived inputs can be reviewed or overridden, and parameters outside a method’s ranges are flagged.

Nemo’s current feature description lists Holtrop resistance prediction and HCNC export to NavCad. The export provides a route to a separate analysis application; it should be treated as a data handover rather than the same thing as performing every downstream calculation in Nemo.

For an initial comparison, hold the loading assumptions and speed range consistent. Review whether each method applies to the hull being studied, then investigate differences in inputs before interpreting differences in results. A smooth prediction curve is useful only when its assumptions fit the vessel.

Separate Empirical Prediction From CFD

Empirical resistance estimates and computational fluid dynamics answer related questions through different approaches. Orca3D Marine CFD combines the Orca3D workflow with SimericsMP CFD for resistance and self-propelled analyses, including displacement and planing hulls, multihulls and appendage studies. CFD licensing is separate from the core Orca3D modules.

Nemo documents STL export to Fine/Marine. That supports preparation for an external CFD workflow; it does not establish Nemo as an integrated CFD solver. Decide who will prepare the simulation, select its settings and interpret the outputs as part of the handover.

Consider a more detailed simulation when the study needs to account for features such as steps, trim tabs or appendages that require attention beyond a simplified prediction method. Define the comparison you need before investing in additional simulation detail.

Weight Tracking and Advanced Stability

Orca3D’s Analysis module includes weight, centre-of-gravity and cost tracking. Its Advanced Stability module adds compartment and tank modelling, fluid and solid loads, free-surface effects, intact and damaged stability, criteria evaluation and tank tables.

These are distinct capabilities from basic hydrostatics. For work involving tanks, damage cases or specified stability criteria, review the relevant module and its documented scope against the project requirements. Software output still needs engineering interpretation and review appropriate to the vessel and intended submission.

Nemo’s documented hydrostatics, structural-data extraction and exchange tools can support a wider marine process. Select any additional stability or structural-analysis application around the actual calculation required, rather than assuming that a structural-data export performs the final assessment.

Run a Small, Repeatable Evaluation

Use one representative hull and a recorded loading condition. Establish units, reference axes, displacement and centre-of-gravity assumptions, then produce a section or linesplan, a hydrostatic report and the resistance study relevant to your work.

Make one controlled revision, such as changing a hull dimension or loading assumption, and repeat the study. Assess how clearly the change flows through the geometry and results, how easily colleagues can review it and what information must be transferred to external tools.

This reveals more than a general software demonstration. You are testing whether the method is understandable, repeatable and suitable for the decisions your practice makes.

Explore the Tools in More Detail

Our Orca3D overview explains its design and analysis modules, while the Nemo overview covers its parametric tools and analysis levels. For the underlying feature descriptions, consult the Orca3D capabilities and Nemo developer information.

The wider picture across disciplines, including the architecture, structural and surface-modelling tools, is set out in the Rhino 3D plugins guide by discipline.