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Courses and VMG
Course and VMG (Velocity Made Good) are two terms that appear in every regatta briefing, every tactical discussion, and on every instrument display – and they are often confused. Course describes where the boat is heading and at what angle the wind hits the bow and sails. VMG measures how fast you are actually moving toward your goal – not how fast the boat is sailing over the ground.
Those who clearly distinguish between course and VMG make better decisions upwind, choose the optimal angle on the downwind leg, and understand why a seemingly slower boat still reaches the mark faster. This guide explains both concepts from the ground up, shows practical applications in regatta racing, and provides checklists for helms, tacticians, and trimmers.
What Is a Course in Regatta Sailing?
A sailing course is the direction the bow points, measured relative to the wind direction (True Wind) or relative to a target (mark, gate, finish line). In regatta practice, a distinction is made between:
- Course relative to wind – Upwind, close reach, broad reach, downwind (see Upwind and Reaching)
- Course relative to target – Layline, overstand, direct course to the mark
- Course Over Ground (COG) – actual direction of travel taking current and leeway into account
The True Wind Angle (TWA) is the central measure: it indicates at what angle the true wind hits the bow. TWA 0° would be directly from ahead (unseaworthy), TWA 45° is typical upwind, TWA 90° close reach, TWA 135° broad reach, TWA 180° pure downwind.
Course vs. Speed vs. VMG
Many beginners optimize boat speed (SOG/BSP) – and wonder why they still lose places. What matters is not always the highest speed over ground, but effectiveness in the direction of the goal. That is exactly what VMG measures.
Course triangle upwind: Three vectors form the picture: wind arrow from above (True Wind), boat symbol at an angle (bow direction = course), third arrow horizontal to the wind direction = VMG component. BSP runs along the bow, VMG perpendicular to the wind line, TWA is the angle between wind and bow.
VMG – Velocity Made Good Explained
VMG (Velocity Made Good, often called effective speed in German) is the speed component in a defined target direction. Mathematically: VMG = boat speed × cos(angle between course and target direction).
VMG to Wind (Upwind VMG)
Upwind, the goal is not the mark directly – the boat cannot sail into the wind – but the wind direction itself (or the windward mark as the point upwind). VMG to wind indicates how fast you are making progress to windward.
Typical scenario: An ILCA sails at 5.5 kn BSP at TWA 42°. VMG to wind is about 4.1 kn – significantly less than BSP, but exactly this value decides who reaches the windward mark first.
VMG to Target (Downwind VMG)
Downwind, the goal is the leeward mark or the next gate. Here: A flatter course (wing-on-wing, wider TWA) often delivers more BSP, but a steeper course (by the lee, higher TWA) can improve VMG to the mark – depending on boat class, polars, and waves.
Important: VMG is always direction-specific. "VMG 4.5 kn" without specifying the target direction (to wind, to mark, to gate) is worthless. Instruments therefore show separately: VMG Wind and VMG Course.
The Most Important Points of Sail in Regatta Racing
On a classic windward-leeward course, upwind and downwind legs alternate. Reach legs are added on trapezoid or Olympic courses. Those who master VMG optimization for each leg often gain more places than through maneuver training alone.
VMG and Polars – The Target Angle per Boat Class
Every boat class has characteristic polars (speed tables by TWA and wind strength). From these, the Target TWA is derived – the angle at which VMG is maximized.
Upwind Target Angles
- Planing dinghies (49er, 29er): often steeper (TWA 38°–42°), VMG suffers greatly on too flat a course
- ILCA / Laser: TWA 40°–45° depending on rig and wind strength, fine trim is decisive
- Keelboats (J/70, Dragon): TWA 42°–48°, more leeway, current affects COG
- Catamarans / foilers: extremely class-specific; foiling classes have their own polar curves
Downwind Target Angles
Downwind, the rule often applies: The fastest BSP angle is not automatically the best VMG angle. Many classes reach the mark faster with TWA 140°–155° than with 170°–180°, because more pressure in the sails and better control are possible.
Tip: Train the optimal VMG angle with two-boat testing: same conditions, sail different TWAs, compare GPS tracks. After ten minutes per angle, the target angle often becomes clearer than any polar table.
Course Selection and Tactical Decisions
VMG alone is no substitute for tactics – but poor VMG destroys any tactic. The most important connections:
Upwind: Lifted vs. Headed
- Lifted tack (course shifted toward the wind): hold longer, VMG to wind often increases
- Header (course away from the wind): tack earlier, otherwise VMG loss and worse position
- Layline management: Too early on the layline = VMG loss due to course extension and dirty air
Details on maneuvers when changing course: Gybing and Tacking
Downwind: Angle vs. Pressure
- More wind pressure (pressure) often justifies a flatter course and higher BSP
- Less pressure: steeper course (by the lee) can save VMG to the mark
- Waves: surfing increases BSP briefly – use VMG peaks, then stabilize course again
Blindly following the polar target TWA without considering current, waves, and fleet position regularly costs places. VMG optimization is always situational.
Instruments and VMG Display
Modern regatta boats display VMG on displays, apps, or weather network systems. Important terms:
- VMG Wind – progress in wind direction (upwind/downwind reference)
- VMG Course – progress toward an entered waypoint (mark, gate)
- Target BSP / Target TWA – target values from polars for current wind strength
- Performance (%) – actual VMG compared to polar specification
VMG difference top 5 vs. mid-fleet: Typical regatta: top-5 fleet VMG upwind 4.2–4.5 kn at 12 kn wind; mid-fleet 3.6–3.9 kn. Difference of 0.5 kn VMG = approx. 30–60 m lead per minute upwind. The VMG gap widens on a long windward leg.
Without Instruments: Feeling VMG
Even without GPS, VMG thinking helps:
- Upwind: Are the telltales flowing steadily? Does the boat feel "stiff" or "alive"? Too flat = poor VMG to wind
- Downwind: Do you reach the mark faster with a slight angle change? Compare with training partners at the same height
- After the race: Analyze tracks – where was the VMG drop (bad tack, wrong layline, wrong downwind angle)?
Common Mistakes with Course and VMG
- Too flat upwind – high BSP, poor VMG to wind, layline too late
- Too steep upwind – good VMG short-term, but too slow, fleet overtakes
- Sailing directly downwind (TWA 175°+) – often worse VMG to mark than with 145°–155°
- Confusing course with COG – with current you sail a different course than the bow shows
- Maneuvers without calculating VMG cost – every tack costs 2–4 boat lengths of VMG loss
Frequently Asked Questions
What Is the Difference Between Course and TWA?
Course is direction of travel, TWA is the angle of wind to bow.
Can VMG Be Greater Than BSP?
No, VMG is always a component ≤ BSP.
Which TWA Is Fastest?
Class-specific, found in polars.
VMG Wind or VMG Course Upwind?
VMG Wind for the windward leg.
How Do I Train VMG?
Two-boat testing and GPS analysis.
Checklist: Optimizing VMG in Regatta Racing
Before the Start
- Target TWA and target BSP noted for today's wind strength (polar / experience values)
- Instruments calibrated (wind, GPS, current if applicable)
- Helms and tactician agree on VMG communication ("flatter" / "steeper")
Upwind (Windward Leg)
- Hold target TWA, don't just maximize BSP
- Watch for lifted/header and adjust course
- Don't approach layline too early – VMG suffers with overstand and in dirty air
- Keep tack costs in mind: only tack with tactical or VMG gain
Downwind (Leeward Leg)
- Test VMG angle (don't automatically use 180° TWA)
- Seek pressure, adjust course accordingly
- Plan gybe/tack where VMG drop is minimal
After the Race
- Check GPS track for VMG drops
- Debrief with crew: Where was the course too flat or too steep?
- Document insights for the next regatta
VMG in the Crew Context
Helms, tactician, and trimmers share responsibility for VMG:
- Helms – holds course and target TWA, executes maneuvers
- Tactician – decides when course changes (tack, gybe) improve VMG and position
- Trimmers – optimize sails so target BSP remains achievable at target TWA
Clear commands help: "Two degrees steeper" or "Flatter for VMG" are more precise than "sail faster". More on crew communication in the regatta flow: From Start to Finish
Course Optimization Upwind vs. Downwind
Summary
Course describes where and at what wind angle you are sailing. VMG measures how effectively you are making progress toward your goal – upwind to the windward mark, downwind to the gate. Both concepts together form the foundation of every tactical and technical decision on the regatta course.
Those who understand VMG no longer sail "blindly fast", but with purpose. That is what separates mid-fleet from the podium – regardless of whether you sail Optimist, ILCA, 49er, or J/70.