The efficiency signal separates straightness from speed. CAN181 is the most efficient boat on every leg (4/4) yet finished last. CAN441 won the race (P1) despite being the least efficient on every leg — higher boatspeed compensated. This axis is invisible to elapsed time alone.
STARTgun + 2-min window
2-min cross-track window: pending scaffold. Position-only cross-track at T+2:00: what side had each boat committed to? Same GPS-track pipeline as side-bias on beats. SOG ±30 s from v5 is the base; this block adds the side read at T+120 s.
binding: trackAt(T+120s) → crossTrackSigned → eL/eR chip · same pipeline as LegMetrics.sidePercent
LEG 1 · UPWIND↑real · clean roundings
Side of course % time
L 59%
L 61%
L 57%
Mean offset m from CL
65 L
59 L
84 L
Vs fleet
MID
RIGHTMOST
LEFTMOST
Tacks
1
1
2
VMG kn · pos
2.72
2.70
2.78 ★
Efficiency rhumb/path
0.522 ★
0.510
0.510
Leg time
+21.0
+29.7
15:21.0 ★
181
298
441
EFFICIENCY · RHUMB / PATH ↑ = STRAIGHTER LINE
181
0.522★
298
0.510
441
0.510
441 won L1 (best elapsed) and was the leftmost boat (84 m mean) — the whole fleet worked left, but 441's higher boatspeed more than offset the extra distance sailed. 181 was the most efficient (0.522★) but not fastest. VMG ranks identically to elapsed (constant rhumb) so efficiency is the genuinely new per-boat axis.
WM1 ▲approach · rounding · position
Entry tack last 200 m
R
R
R
Rounding order
P2
P3
P1 ★
Position change (200 m before / after): pending. Who moved up or down at WM1? Rank delta at −200 m and +200 m from the mark.
binding: markRoundingPositionDelta(WM1, −200m, +200m) → rank change Δ
181 was most efficient on L2 (0.864★) yet finished +5.4 s behind 298. 298 won with most gybes (4) and highest VMG — routing paid. 441's L2 MAJOR MOMENT gybe (see Maneuvers) explains its 0.829 worst efficiency.
LM1 GATE ▼▼choice · escape
Gate rounded L/R
L†
R†
L†
Escape timing + position change: pending. Gate choice available; centerline-crossing escape seconds still refining at the rounding baseline.
GateChoice escape refinement + markRoundingPositionDelta(LM1)
181 committed hard left (93%, 262 m mean) and paid the most (+12.0 s). 298 was the only boat right of centerline and won the leg. Efficiency gap 181–441: 0.702 vs 0.675 — the largest of any leg. This is the coaching notebook story in pure position data.
WM2 ▲approach · rounding · position
Entry tack last 200 m
R
R
R
Rounding order
P3
P1 ★
P2
Position change (200 m before / after): pending.markRoundingPositionDelta(WM2)
LEG 4 · DOWNWIND↓run · real efficiency
Side of course
—†
—†
—†
Gybes
2
3
2
VMG kn · pos
4.58 ★
4.51
4.41
Efficiency rhumb/path
0.773 ★
0.772
0.744
Leg time
9:21.6 ★
+8.7
+21.4
EFFICIENCY · RHUMB / PATH
181
0.773★
298
0.772
441
0.744
181 swept L4 — best VMG, best efficiency, best time. Efficiency gap 181 vs 298 is near-zero (0.773 vs 0.772); 441 trails at 0.744, mirroring the L4 major-moment state on Maneuvers (+21.4 s deficit). The L1 gap (0:29) was larger than L4's recovery range.
rhumb = CourseLeg.distance (mark-to-mark haversine) · constant across boats · denominator in efficiency · numerator in leg VMG
Line square / course length / setup stats: pending E-C series.courseSetup.{startLineLength, startLineBias, courseSetupStats} · E-C series
☰ MENU
Map◻Data
v6 · grounded
iPhone · 390pt · full scroll · REAL G3 · position-only efficiency
WHAT'S NEW IN V6 — COURSE PAGE
Chronological order, not wind-first. v5 led with "What the wind really was." v6 follows the race: Start → L1 → WM1 → L2 → Gate → L3 → WM2 → L4 → Wind → Setup. The scrollable spine at the top makes the structure scannable at a glance.
OVERALL efficiency block (new). Mean rhumb/path per boat across all 4 legs. 181 = 0.715★ (most efficient, every leg). 441 = 0.690 (least efficient, every leg). Yet 441 won. The efficiency vs elapsed tension is the coaching frame. FINDINGS-Per-Leg-VMG §5
Position-only VMG + efficiency per leg (new). leg_VMG = rhumb/elapsed (kn); efficiency = rhumb/path (0–1). Zero heading, zero wind — immune to N2 on all three boats. Efficiency ranking differs from elapsed on 3/4 legs. Note: VMG ranking ≡ elapsed (constant rhumb) so efficiency is the genuinely new axis. Proposed E-G under bundle:R-analytics-math.
Runs added (L2, L4). v5/course.html showed beats only. v6 adds both downwind legs with VMG, efficiency, gybe count, and leg time. Run-side (port/starboard) is an honest pending block.
Mark segments (WM1, WM2, LM1 Gate). Between-leg blocks show entry tack (last 200 m) and rounding order. Position change (±200 m window) scaffolded as a pending block.
Tack/gybe count per leg. GPS-course boats (181/298) render with ·gps treatment on counts; 441's counts are precise.
DATA STATUS
All side-bias, VMG, and efficiency numbers are real engine + corpus data (G3 f2a2cacc). Gate choices marked † pending rounding refinement. Run-side (—†) pending downwind calibration. Mean efficiency = (L1+L2+L3+L4)/4 per boat.