What is VMG?
VMG (Velocity Made Good) is the component of your boat speed that goes directly toward your destination. It's the answer to: "How fast am I actually making progress toward where I want to go?"
VMG is crucial because the fastest point of sail is rarely a straight line to your target. You must balance boat speed against sailing angle to optimize your progress.
The VMG Concept
Imagine two boats sailing to the same upwind mark:
- Boat A: Points very high (35° TWA) at 5 knots
- Boat B: Sails lower and faster (45° TWA) at 6.5 knots
Which boat arrives first? Counterintuitively, often Boat B, despite sailing at a wider angle, because its higher speed more than compensates for the extra distance.
The Formula
VMG = Boat Speed × cos(Angle to Target)
For upwind sailing, the angle is your TWA. For downwind, it's 180° minus your TWA.
Upwind VMG
When sailing upwind, you cannot sail directly toward the wind. Instead, you must tack at an angle. The optimal upwind angle maximizes your VMG.
Finding Optimal Upwind Angle
For most boats, optimal upwind VMG occurs around 40-50° TWA, but this varies by:
- Boat type: High-performance boats can point higher and faster
- Wind strength: Stronger winds often allow tighter angles
- Sea state: Waves may require sailing lower and faster
Too High vs. Too Low
- Pinching (too high): Sailing too close to the wind. Boat slows dramatically, VMG drops.
- Footing (too low): Sailing too far from optimal. Good speed but poor angle, VMG drops.
- Sweet spot: The angle where speed × angle gives maximum VMG upwind.
Downwind VMG
Downwind sailing presents the opposite challenge. While you can sail dead downwind (180° TWA), it's often faster to sail at an angle and gybe.
Finding Optimal Downwind Angle
Optimal downwind VMG typically occurs around 140-155° TWA, depending on:
- Boat type: Planing boats benefit more from gybing angles
- Wind strength: Lighter winds may favor dead downwind
- Wave surfing: Can dramatically increase VMG at wider angles
The Gybe Trade-off
By sailing at 145° instead of 180°, you might sail 15% faster. If the speed gain exceeds the extra distance, your VMG improves. This is why you see racing boats constantly gybing downwind.
Example Calculation
- Dead downwind (180°): 7 knots × cos(0°) = 7 knots VMG
- Broad reach (145°): 9 knots × cos(35°) = 7.4 knots VMG
The broad reach wins! You sail faster than you lose in angle.
Using VMG in Racing
Upwind Strategy
- Sail at optimal VMG angle, not maximum pointing or maximum speed
- Adjust for shifts: sail lower in lifts, higher in headers (for best VMG to shifts)
- Monitor instruments: many systems show real-time VMG
- Know your targets: memorize optimal upwind angle for common conditions
Downwind Strategy
- Determine if gybing angles beat dead downwind (usually they do)
- Maximize surfing opportunities at broader angles
- Consider tactical position vs. pure VMG (sometimes worth sailing high to protect)
- Use polar data to find your boat's best downwind angles
Reaching
On reaches, VMG matters when you need to sail toward a mark that's not on a beam reach course:
- If mark is high, sail higher with less speed but better angle
- If mark is low, sail faster at a lower angle
- Calculate which gives better VMG to the mark
VMG vs. Boat Speed
A common rookie mistake is chasing boat speed instead of VMG. Remember:
Critical Insight
Your goal is not to sail fast. Your goal is to reach your destination quickly.Sometimes that means sailing slower at a better angle. VMG measures what actually matters: progress toward the target.
Polar Diagrams and VMG
Polar diagrams show you where maximum VMG occurs:
- Upwind VMG is highest at the angle where (speed × cos(TWA)) is maximum
- Downwind VMG is highest at the angle where (speed × cos(180° - TWA)) is maximum
- Many polar displays include VMG curves explicitly showing optimal angles
Practical VMG Tips
1. Know Your Numbers
Memorize your boat's optimal VMG angles for different wind speeds:
- Light air (6-8 kts): Often need to foot more for speed
- Medium air (10-14 kts): Sweet spot, best VMG usually here
- Heavy air (16+ kts): May need to depower, affecting optimal angle
2. Use Your Instruments
Modern sailing instruments calculate VMG in real-time. Watch for:
- VMG display showing progress toward wind or away from wind
- Target TWA for maximum VMG
- Comparison of actual vs. target VMG
3. Feel the Boat
Experienced sailors develop a feel for optimal VMG:
- Upwind: boat feels "in the groove", consistent heel, good helm balance
- Downwind: boat accelerates smoothly, surfs well on waves
- Off VMG: boat feels either pinched (too high) or wallowing (too low)
Advanced VMG Concepts
VMG in Shifts
When the wind shifts, your optimal VMG angle changes:
- Lift: Can point higher while maintaining speed, VMG increases
- Header: Must fall off to maintain speed, VMG decreases
- Strategy: Tack on headers, sail lifts to maximize average VMG
VMG in Current
Current affects your actual VMG over ground. You must account for:
- Favorable current: Can sail at wider angles, current helps VMG
- Adverse current: Tighten angles, minimize time in current
- Cross current: Adjust heading for best VMG to target
Master VMG with Data
ChartedSails provides comprehensive VMG analysis:
- Real-time VMG compared to optimal from polars
- VMG performance on every leg of every race
- Identification of when you're sailing optimal vs. suboptimal angles
- Historical VMG trends to track improvement
- Comparison with fleet to see who's optimizing VMG best