VMG Explained
Velocity Made Good
You can also try our VMG Tool which will help you calculate your Velocity Made Good for a given SOG and tacking angle, either upwind or gybing downwind.
Understanding VMG
Sailing Straight Isn’t Always Possible
A guide to VMG
The puzzle every sailor faces
Imagine you want to sail due north, and the wind is blowing straight down from the north. Simple, right? Just point the bow north and go.
Except… you can’t. No sailboat can sail directly into the wind. Try it and your sails flap uselessly in what sailors call “irons.” Most boats can only sail as close as about 45–60° off the wind direction. So how do you actually get to a destination that’s directly upwind?
You tack or zigzag. And that zigzag is where VMG comes in.
What VMG Means
VMG = Velocity Made Good.
It’s not how fast your boat is moving through the water – it’s how fast you’re moving towards where you actually want to go.
Think of it like this:
- SOG (Speed Over Ground) = your actual speed, in any direction.
- VMG = the portion of that speed that’s getting you closer to your destination.
If you’re sailing at 8 knots but at a 60° angle away from your target, only part of that 8 knots is useful. The rest is sideways progress you’ll have to “undo” on the next tack.
Check out the Clip Above
The animation walks through an example:
- The boat starts at the bottom, wanting to reach a point 2 nautical miles due north.
- The wind is blowing from the north, so sailing straight is impossible.
- The catamaran tacks – zigzagging on alternating headings of 060° (port tack, heading northeast) and 300° (starboard tack, heading northwest).
- Watch the COG (Course Over Ground) indicator flip from 060° to 300° each time the boat tacks. That’s the heading change in real time.
- The dashed white centerline is the rhumb line – the straight-line route to the destination. The boat never sails along it; it sails around it.
The numbers that tell the story
The summary:
| Metric | Value | What it means |
|---|---|---|
| Total distance sailed | 4.0 NM | What the boat actually travelled through the water |
| Rhumb line distance | 2.0 NM | The straight-line distance to the destination |
| Overall heading | 000° (due north) | The net direction of progress |
| Time at 8 knots | 30 minutes | Half an hour of sailing |
| VMG | 4.0 knots | The effective speed toward the goal |
Here’s the key insight:
“At 60 degree, you sailed twice the distance to gain half the speed northward. That’s VMG.”
You moved through the water at 8 knots, but because half of every leg was “sideways” effort, your real progress toward the destination was only 4 knots. You covered 4 NM of water to make 2 NM of useful ground.
Why this matters in the real world
Once you understand VMG, you start asking a much smarter question on the water. Instead of “How fast am I going?” you ask “How fast am I getting there?”
This changes decisions:
- Pointing higher (sailing closer to the wind) reduces distance but usually slows the boat down. Point too high and you will increase your leeway. Remember, it’s your COG (course over ground) you are interested in, not your heading.
- Coming off (bearing away slightly) speeds the boat up but adds distance.
- The sweet spot – the angle where VMG is maximised – is what every sailor is hunting for. It’s often not the highest speed and not the tightest angle. It’s the best compromise. It will depend on your boat as well. Perfprmance cats can point much higher than cruising cats.
Modern instruments and chartplotters like B&G Nav and Raymarine will display VMG live if you log your destination – it’s the number serious sailors watch on every upwind leg.
The takeaway
Sailing upwind is a balance. You can’t go where the wind comes from, so you trade distance for direction. VMG is the scoreboard that tells you whether that trade is paying off.
Next time you see a fleet of boats zigzagging upwind, you’ll know they’re not lost – they’re all chasing the sweet spot.