Last session I sailed with a NeilPryde V8 9.4 and my Loft Switchblade 8.5 in light wind, reaching a top speed of around 40 km/h.
When using the NeilPryde, the low‑end performance was clearly better. Of course, you can fine‑tune the sail shape a bit, but physics plays a big role here: a longer boom simply means more leverage and power, which pushes the fin harder and helps you plane earlier and stay planing longer. It’s just how it works.
The same principle applies to mast length. A 520 cm mast is stiffer than a 490 cm one, and that stiffness translates into more power. So, even though sail shape and belly adjustments help, a longer boom and longer mast naturally make the sail perform better at the bottom end.
Here’s the catch though: the amount of required power and lift is directly linked to the combined weight of the rider and the equipment. A 60 kg sailor planes with roughly half the power needed by a 120 kg sailor. That means there’s a point for every bodyweight where going to a bigger sail no longer improves early planing. In other words, there are many “truths” depending on rider weight. In a world without heavy windsurfers, there would be no need for sails over 9 m². For me a 9.4m2 was a small improvement.
