Sailing by the Lee — Explained Simply

Sailing by the lee happens when a sailboat sails so deep downwind that the wind crosses the stern and starts pushing on the back side of the mainsail.

Normally, sails are designed to work with wind flowing smoothly over the windward side. When sailing by the lee, the wind hits the sail from the opposite direction while the boom remains out on the same side.

Think of it as sailing slightly past a normal dead-downwind course.

The Difference Between a Run and By-the-Lee

Sailing on a Run

• Boat points directly downwind.
• Wind comes straight from behind.
• The mainsail acts mostly like a parachute.
• The boom is fully eased out.
• Stable only if the wind stays perfectly centered.

Sailing by the Lee

• Boat turns slightly farther away from the wind.
• Wind crosses over the stern and touches the leeward side of the sail first.
• The mainsail fills “backwards.”
• The boom stays on the same side as the wind.
• The airflow can create more lift and speed.

Why It Can Be Faster

On a dead run, sails mostly drag through the air like a parachute.
Aerodynamically, this is inefficient.

When sailing by the lee:

• Air flows more smoothly across the sail.
• The sail can generate a small amount of lift instead of pure drag.
• The boat may move faster and feel freer.

It is similar to how airplanes generate lift from airflow over wings.

Why Racers Use It

Experienced sailors sometimes use it because:

1. Better Boat Speed

A slight by-the-lee angle can produce:

• smoother airflow
• less sail collapse
• improved VMG (Velocity Made Good) downwind

2. Fewer Jibes

Instead of sailing a series of broad reaches with multiple jibes, racers may hold a by-the-lee course longer.

3. More Stable in Light Air

Sometimes a dead run causes:

• rolling
• collapsing sails
• unstable airflow

By-the-lee sailing can steady the mainsail in certain conditions.

The Danger: Accidental Jibe

This is the biggest risk.

Because the wind is already trying to push the sail from the opposite side:

• a small steering mistake
• wave movement
• wind shift

can violently throw the boom across the boat.

This is called an accidental jibe.

An uncontrolled jibe can:

• injure crew
• damage rigging
• break the boom
• destabilize the boat

How to Recognize Sailing by the Lee

You are probably sailing by the lee if:

• The wind is coming over the same side as the boom.
• The mainsail appears slightly “backwinded.”
• The upper telltales stream toward the mast.
• The boat feels quick but sensitive to steering.
• The boom wants to swing unexpectedly.

Steering Technique

Good sailors use:

• very smooth helm movements
• constant attention to wind angle
• vang control to stabilize the boom
• preventers offshore for safety

Even a few degrees of steering change matters.

Simple Visualization

Imagine:

• Wind from directly behind = normal run
• Turn the boat a few more degrees away
• Wind now curls around and presses the backside of the sail

That is sailing by the lee.

Key Concept

Sailing by the lee is:

• not beginner sailing
• aerodynamically useful
• tactically valuable
• potentially dangerous

Expert sailors use it deliberately for:

• speed
• smoother airflow
• race tactics
• downwind efficiency

but always with careful control of the boat and boom.