Black Foils · fleet analysis

Takeoff technique and the upwind VMG angle

• Day 2026-09-18
• Window 12:00-15:30 UTC
• Boats NZL, AUS, CAN, DEN, ESP, USA
• Takeoffs 49

Two questions, one day of data. Takeoff turns out to be an unusually tight speed gate that the whole fleet meets within a couple of km/h — and the daggerboard rake is a trigger pulled at that speed, not a run-up to it. Upwind, there is a clear best angle, and almost nobody sailed it.

Takeoff is a speed gate, and everyone meets it

Across 49 takeoffs the median speed is 30.3 km/h (16.4 kt), and the spread between boats is almost nothing — NZL takes off at 29.8 and USA at 31.0. The coefficient of variation across every takeoff is 4.2%. Whatever else differs between these teams, the speed at which an F50 will fly does not.

The rake is a trigger, not a run-up

You asked for the speed at the moment the boat goes to maximum rake. That moment is later than it sounds: the median boat commits to full rake just 2.0 seconds before it flies, at 30.0 km/h — which is within half a km/h of the takeoff speed itself. The boats are not raking early and accelerating onto the foils; they reach flying speed and then pull the trigger.

80% of takeoffs peg the board at the mechanical stop (7.79°, which is the highest value any of these six boats records all day). So "how much rake" is not really a variable — it is full rake, nearly always. The variable is when.

Boat	Takeoffs	Speed at full rake	Speed at takeoff	Peak rake	Rake lead (s)	TWS
NZL	13	29.3	29.8	7.8	2.5	13.2
CAN	8	30.4	29.9	7.7	1.8	14.5
DEN	5	30.3	30.3	7.8	3.0	14.9
AUS	7	30.4	30.5	7.8	2.5	13.7
ESP	9	29.9	30.7	7.7	1.5	14.6
USA	7	31.1	31.0	7.8	1.5	15.6

The upwind angle: 50°, and the fleet sailed 28° wider

In the one wind band with enough data to answer the question — 12–16 km/h (6.5–8.6 kt) — VMG peaks at 50° TWA at 39.9 km/h boat speed, giving 26.6 km/h VMG (14.4 kt). That is a real peak rather than the edge of the data: 46° and 52° either side both give less (26.2 and 25.0).

Why footing off costs you

Normally you accept a wider angle because it buys speed. On this day it did not. Boat speed is essentially flat across the whole range — about 38–40 km/h from 46° all the way out to 70°, and it falls beyond that. With no speed to gain, widening the angle only costs the cosine, so VMG drops monotonically.

Boat	Minutes upwind	Median TWA	Time tighter than 55°	BSP km/h	VMG km/h
DEN	3.4	64	7.8%	37.9	18.14
NZL	5.6	68	16.9%	38.8	16.46
ESP	8.7	66	17.0%	36.4	15.33
CAN	5.0	68	5.3%	39.7	13.07
AUS	5.1	74	6.2%	37.2	11.42
USA	3.1	77	8.5%	36.4	10.36

Which wind bands could actually be answered

You asked for bands from 6 to 14. Two things get in the way. The speed channels are km/h, not knots, despite what the app's sliders say — and the upwind foiling data only spans 11.0 to 18.9 km/h (5.9–10.2 kt). Within that, only two bands have enough angular coverage to show a peak rather than an edge. The rest are reported honestly as unanswerable rather than given a number.

TWS km/h	TWS kt	Samples	Best TWA	BSP km/h	VMG km/h
8–10	4.3–5.4	65	—	—	—	not enough data
10–12	5.4–6.5	559	52	39.3	24.8	not bracketed
12–14	6.5–7.6	2399	50	39.8	26.9	optimum found
14–16	7.6–8.6	1318	52	39.4	26.5	optimum found
16–18	8.6–9.7	435	52	39.0	25.4	not bracketed
18–20	9.7–10.8	211	—	—	—	not enough data
20–22	10.8–11.9	105	—	—	—	not enough data

What I would take from this

Takeoff: there is little to coach in the speed — everyone hits 30 km/h. The question worth asking is whether committing rake earlier, while still accelerating, gets the boat up sooner. Right now the whole fleet does the same thing: reach flying speed, then rake.

Upwind: this is the actionable one. 50° at 40 km/h was worth 26.6 km/h of VMG; the fleet's habitual 77° was worth far less. Median angle tracks median VMG straight down the fleet: DEN sailed the tightest median (64°) and got the best VMG (18.1); USA sailed the widest (77°) and got the worst (10.4).