A Sail Works Like a Wing, Not a Parachute
A sail catches wind to drive a boat. Upwind, it generates lift rather than being pushed.
A sail is a sheet of fabric set to catch the wind and drive a vessel. Downwind it is simply pushed, but sailing upwind works quite differently: the curved sail acts as a vertical wing, generating lift perpendicular to the airflow, while the keel stops the boat sliding sideways. The combination drives the hull forward at an angle into the wind, which is why a boat can sail closer to the wind than a raft ever could. *Sail* is Old English *segl*.
- A sheet of canvas. *Hoisting the sail.*
- To travel by water. *Sailing to France.*
- A windmill blade. *The mill's sails.*
- Set sail. *They set sail at dawn.*
- Old English — *segl*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | sail | A sail. |
| Verb | sail | Sailing. |
| Agent | sailor | A sailor. |
| Compound | sailcloth | Sailcloth. |
| Old English | segl | A sail. |
- They raised the sail.Object.
- The boat sailed upwind.Action.
- A sail is a vertical wing.Physics.
Why a boat can sail upwind
- The curved sail generates lift like an aircraft wing
- That force acts roughly sideways to the boat
- The keel resists sideways motion through the water
- What remains drives the hull forward
- No boat sails directly into the wind — it tacks in zigzags
Old English *segl*, of Germanic origin, related to Dutch *zeil* and German *Segel*.
How can a boat sail into the wind?
The sail acts as a wing generating lift, and the keel converts that sideways force into forward motion.
Can a boat sail directly into the wind?
No. It sails at an angle and zigzags, a manoeuvre called tacking.