StowMind is a specialized workbench for FreeCAD 1.1, built for naval architects, cargo planners, and heavy lift engineers. It bridges the gap between 3D ship models and the calculations that depend on them — all inside a single FreeCAD document.
Calculations are aligned with established maritime and lifting standards, including DNV-ST-N001, the DNV Guidance on Stability of Lifts, the IMO CSS Code Annex 13 (2021), and the 2008 Intact Stability Code (IS Code 2008) under SOLAS.
Import hull geometry from GF spant files, DXF, STL, IGES/STEP, or FreeCAD native files. StowMind converts meshes to watertight solids, mirrors half-spants to full sections, and loft them into a complete hull. Four example vessels (Series 60, Wigley) are included for testing.
Video: Hull Import & StowMind Object Creation
Calculate hydrostatic tables, tank data, and cross curves directly from the hull solid. Two methods: fast slice-based calculation from existing frames, or a complete pipeline extracting 50 evenly distributed frames with full pantocarenes (KN curves) for 13 heel angles. Results are stored as FreeCAD spreadsheets and plotted automatically.
Video: Hydrostatics & Pantocarenes
Define tanks as parametric solids with fluid type and fill level. Create weight objects for lightship, crew, provisions, hatch covers, deck equipment, and project cargo. All masses and centers of gravity feed directly into the load condition calculation.
Import cargo lists from Excel or 3D models (STEP/IGES/STL). Automatic placement with collision detection respects deck topology, obstacles (cranes, superstructure), and already placed cargo. Stackable cargo is handled by a specialized stacking algorithm. The stowage plan is the 3D model — not a separate document.
Video: Excel Import & Automatic Placement
The Load Condition aggregates all tanks, weights, cranes, and cargo into a single spreadsheet. One click calculates total mass, center of gravity, sinkage, trim, metacentric height (GMt), and stability assessment against the mandatory intact stability criteria of SOLAS Chapter II-1 and the 2008 Intact Stability Code (IS Code 2008), Part A. A floating Stability Monitor updates every 4 seconds while you work.
Complete lashing calculation per IMO CSS Code Annex 13 (2021 Amendments), Advanced Calculation Method. The calculation covers both direct and half-loop lashing arrangements, evaluates forces from ship-induced accelerations and GM-dependent roll angles, and verifies MSL values per side. A 3D editor enables fast and intuitive lashing design. The PDF export produces a ready-to-print securing certificate with force balance, tipping check, and PASS/FAIL evaluation.
Video: Interactive 3D lashing design, example 96t Trafo
Calculate the GZ righting lever curve directly from hull geometry — no external software needed. Volume-constant bisection iteration over 13 heel angles. SOLAS Chapter II-1 and IS Code 2008 (2008 Intact Stability Code), Part A criteria — including area under the curve, maximum GZ, and vanishing angle — are checked and plotted. Projected wind and cross-sectional areas are computed for weather criteria.
Model ship cranes as parametric 3D objects with load-radius curves. Single hook and tandem lift solvers calculate optimal boom angles, distribute load between two cranes, and simulate the swing path step-by-step. Rigging verification per DNV-ST-N001 / Noble Denton includes shackle selection, grommet sizing, traverse design, and automatic BOM generation with PDF drawing export.
For complex lifts where the centre of gravity lies above the lifting points, StowMind applies the methodology of the DNV Guidance on Stability of Lifts, assessing overturning risk under disturbing factors including wind force, rigging length tolerances, and CoG shift.
Video: Tandem Lift Simulation & Rigging Wizard
The Dynamic Module is a fully integrated suite that extends StowMind into the time‑domain and seaway environment. Based on the same hull geometry, load condition, and hydrostatic data, it provides five core operational analysis tools that share a common data model and workflow:
All features are powered by the same Capytaine BEM solver, use the same wave spectra (JONSWAP / Pierson‑Moskowitz), and produce results that flow directly into your FreeCAD spreadsheets and 3D models.
Compute full 6‑DOF Response Amplitude Operators (RAOs) directly from your hull geometry — no separate software, no file export/import hassle. StowMind integrates the open‑source boundary element solver Capytaine into your FreeCAD workflow.
The RAO results are the foundation for all subsequent crane and mooring analyses. They are stored in a single NetCDF file and remain linked to your FreeCAD document.
Video: RAO Analysis – Frequency Sweep, Directional Sweep, and Interactive Plot Filters
Using the RAOs, this module calculates the dynamic load reduction for ship cranes under a given sea state. It accounts for the full 6‑DOF motion at the hook point with phase‑correct complex superposition – avoiding the common over‑estimation that occurs when magnitudes are summed directly.
The module reads crane positions and hook loads directly from your LoadCondition spreadsheet. The resulting dynamic SWL is displayed in a table and can be exported for operational planning.
Video: Crane Load Analysis – From RAOs to dynamic SWL reduction
Full mooring analysis including static equilibrium (surge, sway, yaw) under wind, current, and waves, plus spectral tension and time‑domain simulation. The integrated Mooring Editor allows interactive placement of fairleads and pollers directly on the 3D model.
The mooring analysis uses the same RAOs and wave spectrum as the crane module. The static equilibrium handles asymmetric mooring arrangements and environmental loads from any direction, giving you a complete picture of vessel station‑keeping.
Video: Mooring Analysis – Editor, static equilibrium, spectral tensions, and time‑domain
This module provides a two‑stage approach to operability assessment. First, the expensive seakeeping integration is computed once per load condition and stored as a response matrix. Then, multiple operational scenarios (crane SWL, required lift weight) can be evaluated instantly – without re‑running BEM or spectral integration.
This design makes “what if?” studies practical: changing the required lift weight or switching to a different crane does not require a new Capytaine run – just a few milliseconds of array algebra.
Example: After computing the response matrix for a given vessel in ballast condition, you can instantly evaluate operability for any crane SWL and any required lift weight – and compare it against the full‑load condition side‑by‑side.
This module extends the acceleration analysis from the crane hook to any arbitrary point on the vessel – cargo corners, lashing points, sensitive equipment, container stacks, etc. It uses the same RAO‑based spectral method and allows user‑defined acceleration limits per axis.
This feature is particularly useful for verifying that cargo lashing systems or sensitive equipment remain within their allowable acceleration envelopes under the given seaway.
Use case: Define the corners of a heavy transformer as POIs, set a vertical acceleration limit of 2.0 m/s², and run the analysis for your design sea state – the table immediately shows which corners pass and which fail.
StowMind's calculations reference the following international maritime and lifting standards. This section is intended as a quick reference for engineers, surveyors, and automated systems evaluating the tool's applicability.
Crane load and rigging calculations for controlled lifting operations in onshore, inshore, and offshore environments. Includes shackle selection, grommet sizing, and traverse design verification.
Assessment of overturning risk for complex lifts where the centre of gravity lies above the lifting points. Considers wind force, rigging length tolerance, crane movement, and CoG shift.
Advanced Calculation Method for cargo securing. Covers direct and half-loop lashing arrangements, force evaluation from ship-induced accelerations, and GM-dependent roll angles.
Verification against mandatory intact stability criteria of the 2008 Intact Stability Code (IS Code 2008), Part A, as applied under SOLAS. Includes righting lever curve requirements and severe wind and rolling criteria.
Partial safety factors (γ_pret, γ_env, SC) for mooring line tension analysis, including damaged condition checks and spectral tension evaluation.
Standard wave spectra used for RAO, crane load, and operability analysis. Compatible with arbitrary wave scatter diagrams for site-specific operability assessment.
Practical walkthroughs on the StowMind YouTube channel – installation, hull handling, tank and cargo creation, lashing, and the Dynamic Module.
StowMind comprises 99 modules across nine functional areas. All share the same FreeCAD coordinate system, the same hull geometry, and the same data model.
Import, convert, loft, scale
Frames, curves, pantocarenes
Parametric fluids, fill levels, FSM
Lightship, cargo, equipment
Topology, coamings, covers
Sink & trim, GZ, monitor (SOLAS / IS Code 2008)
Projected areas, decals, labels
Single hook, tandem, monopile (DNV-ST-N001)
Shackles, grommets, traverses, BOM (DNV-ST-N001)
6‑DOF response, directional sweep
Dynamic SWL reduction, accelerations
3‑DOF equilibrium, spectral tensions, time‑domain
Response matrix, instant operability, vessel comparison
Acceleration checks, limits, pass/fail for arbitrary points
One document. One model. One source of truth.
Every change propagates. Adjust a tank fill level, move a cargo unit, or rotate a crane — the load condition, stability, and all dependent reports update automatically.
"It is only those who do nothing who makes no mistakes"