Physics of Sailing

Breaking down the complicated concepts of speed, acceleration, torque, fluid mechanics, and surface physics, Physics of Sailing provides a lively, easily accessible introduction to the basic science underlying the sport of sailing. It illustrates the many ways physics can be used to understand the principles of sailboat propulsion and how a scientific understanding of the boat, wind, and water can lead to more skillful sailing.

After a brief but insightful tour of the history of sailing, the book explores the physics involved in making faster sailing crafts for both upwind and downwind sailing, including Newton’s impact theory of fluid resistance and lift and drag phenomena. It compares possible sail shapes, presents measurements of hull smoothness, and describes wind turbulence, the nature of water waves, and the structure of wakes. Using the physics of optics, the author also explains the connection between water’s appearance and the wind. Along with a glossary of sailing terms, he includes many examples throughout to illustrate the concepts in practice.

Avoiding unnecessary formalisms, this book skillfully applies the principles of fluid mechanics to sailboat technology and the art of sailing. It should help you become a more knowledgeable sailor.

John Kimball is a professor of physics at the University of Albany.

Depart, Depart from Solid Earth
Why Sailing, Why Physics, Why Both?
Origins
There’s Much More
Downwind—The Easy Direction
Speed
Forces
Boatspeed
Wind Shadow
Acceleration
Examples
The Speed Limit
Upwind—The Hard Direction
Overview
Iceboats
Sailboat Speeds
Why Is Sailing Upwind So Complicated?
Tipping, Torques, and Trouble
Roll, Pitch, and Yaw
Torques
Centers of Mass, Buoyancy, and Effort
Catamaran
Iceboat
Monohull
Staying Upright
Steering and Helm
Dynamics
Upright Mast
Personal Torques
See How the Mainsail Sets
Spinnaker
Mainsail and Jib
Real Sails
What Really Counts
Fluid Dynamics
Navier–Stokes Equation
Viscosity
Reynolds Number
Boundary Layers
Euler Equation
Why Are Fluids So Complicated?
Surfaces
An Example
Inadequate Theory
Curiosities
When Is It Smooth Enough?
Waves and Wakes
Wave Shape
Water Motion
Gravity Waves
Capillary Waves
Damping
Wind and Waves
Wave Packets and Group Velocity
An Example
Wakes
The Importance of Waves
Wind
Two Examples
Turbulence
Wind up High
Weather
Apologies
Strategy
Directions
Constant Preferred Direction
Variable Preferred Direction
Current
Least-Time Path
Light Analogy
Mathematical Approach
Predicting the Wind
Real Sailing
Finally
Sailing Glossary
Index