PROPULSE — Conceptual Ship Resistance & Power Prediction

Open-source tool for resistance and propulsive efficiency prediction in the conceptual design phase of displacement ships.

Features

• 3 prediction methods: Holtrop & Mennen (1982), Holtrop (2001), ITTC 1978
• Resistance components: frictional, wave-making, viscous, appendage, additional
• Propulsion efficiencies: hull, propeller open-water, rotative, shaft bearing
• Speed sweep: full resistance and power curves over a speed range
• Modern web UI: interactive charts, bilingual (EN/ES)
• REST API: integrate with your own design workflows

Quick Start

Prerequisites

• Python 3.10+
• Node.js (for frontend dev server)

Install

# Clone the repository
git clone https://github.com/nantonelli94/propulse.git
cd propulse

# Install backend dependencies
pip install -r backend/requirements.txt

# Start the backend (port 8000)
python main.py

Run Frontend

cd docs
python -m http.server 3000
# Open http://localhost:3000

Run Tests

cd backend
pytest tests/ -v

API Endpoints

Method	Endpoint	Description
GET	/	API info
GET	/health	Health check
GET	/methods	List available methods
POST	/predict	Single speed prediction
POST	/sweep	Speed sweep prediction

Example API Call

curl -X POST http://localhost:8000/predict \
  -H "Content-Type: application/json" \
  -d '{
    "geometry": {
      "LWL": 100, "B": 15, "T": 5, "D": 3.5,
      "Cp": 0.65, "Cb": 0.70, "Cm": 0.85, "Cwp": 0.75,
      "LCB": 0, "S": 1800, "Disp": 3500, "Vs": 8,
      "rho": 1025, "nu": 1.188e-6, "g": 9.81,
      "Z": 4, "P_D": 0.8, "Ae_Ao": 0.7, "shaft_angle": 0,
      "has_bulbous_bow": true, "has_transom": false,
      "has_skeg": false, "has_strut": false, "has_stabilizer": false,
      "roughness_k": 150e-6, "windage_coeff": 1.0, "air_density": 1.225
    },
    "Vs": 8.0,
    "method": "holtrop1982"
  }'

Methods

Holtrop & Mennen (1982)

Classic approximate power prediction method widely used in conceptual design.

• Range: Fn 0.15–0.45, Cp 0.55–0.85
• Accuracy: ±5–10% for displacement ships
• Best for: General cargo, tankers, bulk carriers

Holtrop (2001)

Revised method with updated coefficients.

• Range: Fn 0.15–0.50, Cp 0.55–0.85
• Accuracy: ±4–8% for displacement ships
• Best for: Higher-speed displacement ships

ITTC 1978

ITTC Recommended Procedure 14.302-01.

• Range: Fn 0.15–0.45
• Accuracy: ±6–12% for displacement ships
• Best for: Benchmark comparisons, validation

Project Structure

propulse/
├── backend/
│   ├── api/
│   │   └── main.py          # FastAPI application
│   ├── models/
│   │   └── geometry.py      # Pydantic data models
│   ├── methods/
│   │   └── __init__.py      # Resistance prediction methods
│   ├── tests/
│   │   └── test_methods.py  # Unit tests
│   └── requirements.txt

├── docs/                     # Frontend web UI + methods docs
│   ├── index.html
│   ├── assets/
│   │   └── style.css
│   └── src/
│       └── app.js
├── data/
│   ├── examples/
│   └── validation/
├── scripts/
├── .github/
│   └── workflows/
│       └── deploy.yml       # CI/CD for GitHub Pages
├── main.py
└── README.md

License

MIT License — see LICENSE for details.

References

1. Holtrop, J., & Mennen, G. G. J. (1982). "An approximate power prediction method." International Shipbuilding Progress, 29(335).
2. ITTC (1978). "ITTC Recommended Procedures: Performance Prediction Method." 14th International Towing Tank Conference.
3. Holtrop, J. (2001). "Ship design: resistance and propulsion." Delft University of Technology.

Author

Nicolas Antonelli — Marine Engineer, CFD Analyst

• GitHub: @nantonelli94
• LinkedIn: Nicolas Antonelli

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PROPULSE is a community-driven open-source project. Contributions, bug reports, and feature requests are welcome!