Understanding Your TWS, TWA, and VMG — Explained Simple, Practical, Not Scary

If you’ve spent any time sailing with instruments on, you’ve seen these letters: TWS, TWA, VMG.

They show up on chartplotters, apps, cockpit displays — and often in conversations that sound more complicated than they need to be.

The truth is, these numbers aren’t there to turn sailing into maths. They’re there to help you understand what the wind is doing relative to your boat, and how well you’re actually moving where you want to go.

Let’s slow this down and keep it practical.

What TWS really means on a sailboat

TWS stands for True Wind Speed. In simple terms, it’s the wind speed out in the open, not affected by how fast your boat is moving.

This matters because the wind you feel on deck is not always the real wind. When you’re sailing fast, especially upwind, the apparent wind builds. Downwind, it often feels lighter. TWS strips all that away and tells you what the weather is actually doing.

Why this helps:

• It gives you a clearer picture of conditions

• It’s useful for sail selection

• It helps you compare forecasts with reality

If the forecast says 15 knots and your TWS shows 14–16, you’re roughly where you expected to be.

TWA: the wind’s angle, not its attitude

TWA means True Wind Angle. This tells you where the wind is coming from relative to your bow, measured in degrees.

Think of it like this:

• 0° = wind straight on the nose

• 90° = wind on the beam

• 180° = wind dead behind

Unlike apparent wind angle, TWA doesn’t change dramatically with boat speed. It’s calmer, more stable, and easier to use for understanding sailing modes: beating, reaching, running.

Why sailors like TWA:

• It helps you recognize when you’re truly close-hauled or cracked off

• It’s useful for comparing performance over time

• It makes sail trim discussions clearer

If someone says, “We’re sailing well at 135° TWA,” you know exactly what kind of sailing that is.

VMG: the number that answers “are we getting there?”

VMG stands for Velocity Made Good. This is the most misunderstood one — and arguably the most useful.

VMG tells you how fast you’re actually moving toward (or away from) your target. Not your speed through the water. Not your speed over ground. But progress toward where you want to go.

Upwind, VMG answers:

Are we actually getting closer to the mark?

Downwind, it answers:

Are we really moving away from where we started?

Sometimes this leads to surprising truths. Sailing slightly slower but at a better angle often gives a better VMG than pinching hard or sailing too deep.

This is where sailors start trusting numbers — not blindly, but thoughtfully.

How cruisers can use this without overthinking

You don’t need to stare at instruments all day.

These numbers are most helpful when:

• trimming sails after a change in wind

• choosing between sailing a little higher or lower

• checking whether your “comfortable” angle is still efficient

• comparing today’s sailing to yesterday’s in similar conditions

A quick glance can confirm what your body already feels — or gently challenge it.

And if you’re using modern navigation tools, it helps to know which ones actually support decision-making, rather than distract from it. That’s exactly why we put together our guide to the Best Sailing Apps Cruisers Actually Use (Navigation, Weather & Planning) — tools that work with seamanship, not against it.

Numbers don’t replace seamanship — they support it

Good sailors don’t chase perfect numbers.They notice patterns.

TWS rising steadily. TWA shifting with a front. VMG dropping when comfort takes over — or improving when trim is right.

Used calmly, these figures help you understand why the boat feels good, not just that it does.

A quiet confidence boost

Once TWS, TWA, and VMG stop feeling mysterious, sailing becomes more relaxed. You’re no longer guessing whether things are “right.” You’re observing.

And observation — more than speed — is what builds confidence at sea.

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