Physics Sailing Simulator

A comprehensive sailing simulation with realistic physics and modular controller architecture for easy development and testing of navigation algorithms.

Kehillah Sailbot boat simulation program for the 2025-2026 Sailbot competition

Quick Start

# Run with default configuration
python3 run_simulator.py

# Run with custom boat configuration
python3 run_simulator.py --config boat_config_simple.yaml

# Force recalculation of polar diagrams
python3 run_simulator.py --recalc-polars

Main Features

• Realistic Physics: Aerodynamic and hydrodynamic forces on boat sails and hulls
• Navigation Testing: Test navigation algorithms with accurate boat behavior
• Performance Optimization: Calculate optimal sail trim, best VMG, and headings
• Modular Controllers: Easy-to-develop custom control algorithms
• YAML Configuration: Simple boat setup without code changes

Project Structure

PhysicsSimulator/
├── simulator/                  # Main simulator package
│   ├── core/                  # Physics simulation core
│   ├── display/               # Visualization system
│   ├── control/               # Control systems
│   │   ├── controllers/       # Modular controllers
│   │   └── algorithms/        # Navigation algorithms
│   └── utils/                 # Utility functions
├── data/                      # Boat performance data
├── docs/                      # Documentation
├── boat_config.yaml           # Default boat configuration
├── boat_config_simple.yaml    # Simple example configuration
└── run_simulator.py           # Main entry point

Configuration

Boats are configured using YAML files. See boat_config.yaml for a complete example.

Simple Example

location: "Newport, Rhode Island"

wind:
  direction: 90   # From East
  speed: 10       # m/s

hulls:
  - name: "main_hull"
    datasheet: "data/naca0015-R7e7-F180.csv"
    material_density: 1000    # Water
    wetted_area: 0.5
    size: 2.0
    position:
      angle: 0
      distance: 0

sails:
  - name: "main_sail"
    datasheet: "data/mainSailCoeffs.cvs"
    material_density: 1.204   # Air
    wetted_area: 10.0
    size: 5.0
    position:
      angle: 0
      distance: 0

See docs/README_CONFIG.md for detailed configuration guide.

Creating Custom Controllers

The modular system allows easy development of custom control algorithms:

from simulator.control.controllers import BaseRudderController

class MyRudderController(BaseRudderController):
    def calculate_rudder_angle(self, target_heading=None, **kwargs):
        # Your custom steering logic
        return rudder_angle  # -10 to +10 degrees

See simulator/docs/MODULAR_CONTROLLER_README.md for details.

Physics & Conventions

Units

• Forces: Newtons
• Distance: Meters
• Angles: Degrees
• Density: kg/m³

Angle Conventions

• Wind: Direction wind is coming FROM (0° = East wind blowing West)
• Calculation angles: Unit circle (0° = East, 90° = North)
• Data angles: 0-180° range for foil data

Core Classes

• Variable: Base class for angles and vectors with automatic unit conversion
• Foil: Calculates lift and drag forces on sails/hulls
• Boat: Manages foils, position, velocity, and force calculations

Development

Requirements

• Python 3.7+
• matplotlib
• numpy
• pyyaml
• Additional dependencies in requirements.txt

Installation

pip install -r requirements.txt
python3 run_simulator.py

Documentation

• Configuration Guide - Detailed YAML configuration
• Modular Controllers - Creating custom controllers
• Control Algorithms - Available algorithms

TODO

• Improve sail physics for realistic jibes and tacks
• Fix variable system display/data angle issues
• Add more sophisticated control algorithms

Citations

• Boeing, G. 2017. "OSMnx: New Methods for Acquiring, Constructing, Analyzing, and Visualizing Complex Street Networks." Computers, Environment and Urban Systems 65, 126-139.

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This is the third iteration of the Kehillah Sailbot boat simulation program