Moding sensitivity — 20260725 · MHU
Straight-line phases · TWS ≈ 34 km/h (19 kt) ·
684 upwind + 448 downwind segments · raw-unit curves shown for the 32–37 km/h band ·
"no-loss" = VMG within 1 km/h of the day's best.
-0.70
Upwind VMG per +1° TWA (foot), km/h
+0.70
Upwind VMG per +1 km/h BSP
+0.86
Downwind VMG per +1° TWA (soak), km/h
+0.82
Downwind VMG per +1 km/h BSP
Sensitivities (VMG ~ TWS + TWA + BSP, TWS-controlled)
| Leg | dVMG/dTWA
(km/h per °) | dVMG/dBSP
(km/h per km/h) |
Break-even
(BSP worth 1°) | No-loss TWA band
(within 1 km/h) | fit |
|---|
| Upwind | -0.70 | +0.70 | 1.00 km/h / ° | ≤ 38° (open below) | R²=0.99 |
| Downwind | +0.86 | +0.82 | 1.05 km/h / ° | ≥ 146° (open above) | R²=0.99 |
Break-even = |dVMG/dTWA| ÷ |dVMG/dBSP|: how much boat speed a degree of angle must buy to keep VMG flat.
Dotted grey line on the TWA panels = polar target TWA. Green band = no-loss TWA range.
Verdict. On 20260725, boat speed barely changed with angle, so VMG was driven by angle, not speed.
Upwind, high mode (point, 41°) made
44.5 km/h VMG vs 39.8 footing at 48°
— +4.7 km/h (12%) for the same speed.
Downwind, soaking deep (145°) made
65.8 vs 59.3 hot at 139°
— +6.5 km/h (11%).
A degree of angle was worth ≈1.0 km/h of BSP (break-even), but footing/heating gained
far less speed than that — so the high-VMG angle won on both legs.
Best-phase targets per TWS bin
Each cell = mean of the top 19% VMG phases in that
2 km/h wind bin (min 3); bins with <8 phases hidden. Mode = TWA median-split within the bin.
VMG bold is the deliverable — the achieved best; grey Polar target is the theoretical optimum for comparison.
Exported to Moding_Targets_20260725_MHU.csv.
Upwind
TWS
km/h | n |
Overall best |
High mode (point) best |
Low mode (foot) best |
Polar target |
|---|
| TWA | BSP | VMG | TWA | BSP | VMG |
TWA | BSP | VMG |
TWA | BSP |
|---|
| 28–30 | 19 | 45 | 59 | 42.0 | 45 | 61 | 43.0 | 49 | 53 | 34.5 | 51 | 63 |
| 30–32 | 89 | 43 | 61 | 44.1 | 41 | 61 | 46.4 | 49 | 61 | 40.3 | 51 | 63 |
| 32–34 | 188 | 41 | 62 | 46.7 | 39 | 61 | 47.6 | 47 | 63 | 42.6 | 50 | 64 |
| 34–36 | 238 | 39 | 61 | 47.4 | 38 | 61 | 48.1 | 46 | 63 | 44.1 | 50 | 65 |
| 36–38 | 122 | 39 | 61 | 47.4 | 38 | 62 | 48.6 | 45 | 62 | 44.2 | 50 | 65 |
| 38–40 | 25 | 39 | 60 | 46.9 | 36 | 58 | 46.5 | 41 | 63 | 46.9 | 49 | 66 |
Downwind
TWS
km/h | n |
Overall best |
High mode (hot) best |
Low mode (soak) best |
Polar target |
|---|
| TWA | BSP | VMG | TWA | BSP | VMG |
TWA | BSP | VMG |
TWA | BSP |
|---|
| 28–30 | 20 | 142 | 80 | 62.9 | 138 | 78 | 58.2 | 143 | 80 | 63.3 | 139 | 76 |
| 30–32 | 80 | 142 | 81 | 63.5 | 138 | 82 | 61.1 | 144 | 81 | 65.5 | 141 | 76 |
| 32–34 | 112 | 146 | 82 | 67.8 | 140 | 80 | 61.6 | 146 | 83 | 69.1 | 142 | 77 |
| 34–36 | 119 | 147 | 82 | 68.4 | 140 | 84 | 63.9 | 148 | 82 | 69.6 | 143 | 78 |
| 36–38 | 76 | 148 | 82 | 68.8 | 143 | 82 | 65.6 | 149 | 81 | 69.9 | 143 | 78 |
| 38–40 | 23 | 148 | 84 | 71.4 | 142 | 84 | 65.6 | 149 | 84 | 72.0 | 145 | 80 |
| 40–42 | 11 | 148 | 81 | 68.4 | 142 | 81 | 64.1 | 148 | 81 | 68.4 | 146 | 80 |
Upwind
Downwind
Reading BSP vs VMG: the middle panels rise monotonically — more speed never costs VMG, so there is no
upper BSP limit; the only "loss" is dropping below the foiling floor (≈54 km/h up,
≈74 km/h down). The moding trade-off lives in TWA, not BSP.
Caveat: the sparsest extreme-angle bins (few segments) partly reflect wind-direction scatter; within-tack the
normal speed-for-height trade-off is present but weak (corr TWA·BSP ≈ +0.2–0.3), which is why the high-VMG angle pays.