An interactive field guide · 01
Wind is only half the story.
Take the helm. Trim the sails. See what makes a boat go.
On the water
One mast · main + jib
Close reach / Port tack
0 m sailed
Learn by changing one thing
Experiment 01 · Reaching
Start on a beam reach: the true wind is 90° from the bow. Turn toward the wind, then away from it. Watch the sails, speed, and wind clock respond. Sailing across the wind is often faster than sailing directly downwind.
The boat you’re sailing
Dinghy describes a boat category; sloop, cutter, and ketch describe rigs. Generic boats are representative examples. T10 dimensions use the original Tartan Ten brochure ↗; actual racing displacement varies.
Reading the instruments
True wind is the air moving over the water. Apparent wind is what you feel on a moving boat: true wind minus the boat’s velocity. The clock shows where each comes from, relative to your bow.
VMG is speed made good toward the wind. A negative number means you’re making progress downwind. The shaded clock sector is this boat’s no-sail zone.
This is a simplified, flat-water teaching model. Speed uses an illustrative polar, a soft hull-speed limit, and a sail-trim efficiency curve. Heel and leeway are approximate; force arrows illustrate directions and are not to a shared scale. Trim moves the sails together. There is no current, wave resistance, reefing, capsize, or separate jib control.
Points of sail follow the Royal Yachting Association’s guide ↗. Speeds are illustrative rather than measured performance data.