Sail and keel.

How can a sailboat make progress toward the wind?

Setting up the mechanism…

Forward force: -105.37N
Keel side reaction: 564.48N

Trim: Attached flow model

Fit the components, then test the mechanism.

How can a sailboat make progress toward the wind?

The sail produces a force with forward and sideways components. The keel reacts against the water to oppose sideways drift. Tack across the wind; the boat cannot sail directly into it.

F_forward = L sin β − D cos β

What this model simplifies

Fixed apparent-wind force diagram, not boat-speed prediction. Illustrative lift cap 1.2 and drag polar 0.08 + 0.1 C_L²; stalled trim above 20° excluded.

Read the source · web.mit.edu ↗

Put it to work.

Produce positive forward drive within 5° of a 45° heading.

Make it work.

Produce forward drive toward the wind.

Run

Fine adjustments 4

Apparent windm/s

Wind angle to bow°

Sail angle of attack°

Sail aream²

Sail and keel.

How can a sailboat make progress toward the wind?

Loading the experiment…

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177 interactive experiments. Each has a working model and a challenge to test what you found.

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Ships and marine systems

Sail and keel.

How can a sailboat make progress toward the wind?

Setting up the mechanism…

Forward force: -105.37N
Keel side reaction: 564.48N

Trim: Attached flow model

Fit the components, then test the mechanism.

How can a sailboat make progress toward the wind?

The sail produces a force with forward and sideways components. The keel reacts against the water to oppose sideways drift. Tack across the wind; the boat cannot sail directly into it.

F_forward = L sin β − D cos β

What this model simplifies

Fixed apparent-wind force diagram, not boat-speed prediction. Illustrative lift cap 1.2 and drag polar 0.08 + 0.1 C_L²; stalled trim above 20° excluded.

Read the source · web.mit.edu ↗

Put it to work.

Produce positive forward drive within 5° of a 45° heading.

Make it work.

Produce forward drive toward the wind.

Run

Fine adjustments 4

Apparent windm/s

Wind angle to bow°

Sail angle of attack°

Sail aream²