# Homework Help: Physics of Sailing

1. Feb 28, 2005

### villiami

Hi,
I am considering a project on the physics of sailing (for last year before college, grade 11 for US I think), but I am still searching for am idea. I would quite like to include a small experiment in this project if possible (though not compulsory). If anyone has any ideas/links I would greatly appreciate them. I have considered sail thrust but there are many sites with conflicting information on this.

Thanks Heaps

Last edited: Feb 28, 2005
2. Mar 1, 2005

### Severian596

Hmm...sailboats basically use their keels (or daggerboards in smaller boats) to redirect the lift produced by the sail and propel the boat. I think a pipeline of the components would look like this (assuming you're tacking into the wind to some degree):

- Air passes over the curved surface of the sail and the "back" of the sail, creating a difference in air velocity
- Due to the difference in air density, the difference in velocity creates lift, and the sail attempts to "lift" toward the curved surface of the sail (I assume perpendicular to the sail's curvature)
- The boat's keel stops the boat from simply sliding sideways, and redirects the wind's force so it pushes the boat FORWARD instead. Normally this is at some angle to the way the sail would go if there were no keel.

So maybe figuring net forces and their directions for a given scenario, or two scenarios, would be interesting. Or maybe just ask the question "How can boats sail into the wind?" Many people do not know how the physics of this work.

Last edited: Mar 1, 2005
3. Mar 2, 2005

### gschjetne

If you're thinking about Bernoulli here it's only partially correct. Just picture the sail as an airfoil, which has relative wind, so be careful about your reference frames. Read some about lift, and you should be fine.